CCNA NOTES by ajitpunchhi

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Topics Cover In This Doc 1. Introduction 2. OSI Model 3. Basic Concept of Networking 4. LAN and WAN 5. IP ADDRESSING 6. Routing Protocol 7. Sub netting 8. Static and Dynamic Routing 9. Switching 10.Vlan 11.Security in Vlan 12.Wan 13.Access control list 14.Isdn 15.NAt

Network is the method to share hardware resources and software resources. We can share the resources with the help of operating system like windows, Linux, UNIX etc. To connect multiple networks we have to use internetworking devices like router, bridge, layer 3, switches etc.

Administrator model for networking
Server software: - which software are used to giving services that are server software. Client software: - which gets services.

Server Software

Apache, IIS, Exchange 2003, FTP Server, Send Mail

Client Software

Internet Explorer, Outlook Express, Yahoo messenger, Cute FTP

P R O T O C O L Stack

TCP/IP, IPX/SPX, AppleTalk, Netbeui

P R O T O C O L Stack



If NIC are different then use bridge. If media is different then use Trans-Receive devices.

OSI Model
OSI model is the layer approach to design, develop and implement network. OSI provides following advantages: (i) Designing of network will be standard base. (ii) Development of new technology will be faster. (iii) Devices from multiple vendors can communicate with each other. (iv) Implementation and troubleshooting of network will be easy.


Application Layer

Presentation Layer

Session Layer

Protocol Stack

Transport Layer

Network Layer



(1) Application Layer: Application layer accepts data and forward into the protocol stack. It creates user interface between application software and protocol stack.

(2) Presentation Layer: This layer decides presentation format of the data. It also able to performs other function like compression/decompression and encryption/decryption.

(3) Session Layer: This layer initiate, maintain and terminate sessions between different applications. Due to this layer multiple application software can be executed at the same time.

(4) Transport Layer: Transport layer is responsible for connection oriented and connection less communication. Transport layer also performs other functions like (i) Error checking (ii) Flow Control Buffering Windowing Multiplexing (iii) Sequencing (iv) Positive Acknowledgement (v) Response Connection Oriented Communication Sender Receiver

Request for synchronize Virtual Connection Or Handshaking Negotiation Acknowledgement Send Send Data Transfer Acknowledgement Send Acknowledgement Terminate Or Connection less Communication

Sender Send



Error checking Transport layer generates cyclic redundancy check (CRC) and forward the CRC value to destination along with data. The other end will generate CRC according to data and match the CRC value with received value. If both are same, then data is accepted otherwise discard. Flow Control Flow control is used to control the flow of data during communication. For this purpose following methods are used: (a) Buffer Buffer is the temporary storage area. All the data is stored in the buffer memory and when communication ability is available the data is forward to another. (b) Windowing Windowing is the maximum amounts of the data that can be send to destination without receiving Acknowledgement. It is limit for buffer to send data without getting Acknowledgement. (c) Multiplexing


Multiplexing means combining small data segment, which has same destination IP and same destination service. (iii) Sequencing Transport layer add sequence number to data, so that out of sequence data can be detected and rearranged in proper manner. Positive Acknowledgement and Response When data is send to destination, the destination will reply with Acknowledgement to indicate the positive reception of data. If Acknowledgement is not received within a specified time then the data is resend from buffer memory.


(5) Network Layer
This layer performs function like logical addressing and path determination. Each networking device has a physical address that is MAC address. But logical addressing is easier to communicate on large size network. Logical addressing defines network address and host address. This type of addressing is used to simplify implementation of large network. Some examples of logical addressing are: - IP addresses, IPX addresses etc. Path determination Network layer has different routing protocols like RIP, EIGRP, BGP, and ARP etc. to perform the path determination for different routing protocol. Network layer also perform other responsibilities like defining quality of service, fragmentation and protocol identification.

(6) Data Link Layer
The functions of Data Link layer are divided into two sub layers (i) Logical Link Control (ii) Media Access Control (i) Logical Link Control defines the encapsulation that will be used by the NIC to delivered data to destination. Some examples of Logical Link Control are ARPA (Ethernet), 802.11 wi-fi. Media Access Control defines methods to access the shared media and establish the identity with the help of MAC address. Some examples of Media Access Control are CSMA/CD, Token Passing.


(7) Physical Layer
Physical Layer is responsible to communicate bits over the media this layer deals with the standard defined for media and signals. This layer may also perform modulation and demodulation as required.

Data Encapsulation

Application Layer Physical Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer

Data* Data** Data*** Transport Header | Data Network Header | Segment Header | Packet | Trailer 10

= Segment = Packet = Frame = Bits

Data => Segment => Packet => Frames => Bits

Devices at different Layers
Physical Layer Devices
Hub, Modem, Media, DCE (Data comm. Equipment), CSU/DSU, Repeater, Media converter


Channel Service Unit

Data Service Unit

Data Terminal Equipment

Data Link Layer
NIC, Switch, Bridge

Network Layer Device
Router, Layer 3 Switch

All Layers Device
PC, Firewall

DCE: - DCE convert the bits into signal & send them on media.
FDDI – Fiber Distributed Data Interface Switch forwards frames on the base of MAC address. Router forwards packets on the base of IP address.

LAN Technologies

Ethernet 10 – 10000 mbps 100 m

Token Ring 4 – 16 mbps 100m

FDDI 4 – 16 mbps up to 2 km

Wi-Fi 1 – 108 mbps up to 40 km

Ethernet is the most popular LAN technology. It can support verity of media like copper (UTP, Coaxial, fiber optic). This technology supports wide range of speed from 10mbps to 10000 mbps. Ethernet at Logical Link Control To create logical link control Ethernet uses ARPA protocol also called IEEE802.3. Ethernet adds source MAC, destination MAC, error checking information and some other information to data. Ethernet encapsulation explain as follows Preamble 64 start frame Delimiter 8 Destination MAC 48 49 Source MAC 48 Length 16 Data up to 1500 bytes Frame Check Sequence 16



Ethernet at Media Access Control Ethernet at Media Access Control layer uses CSMA/CD protocol to access the shared media. In these days, we use Ethernet with switches and in switches the technology is made CSMA/CA (Collision Avoidance). So this reason Ethernet is best compare with Token Ring, FDDI & Wi-Fi. Sense the carrier

Receive data


Is carrier busy? No Do we have any data to communicate? Yes


Send data over media

Back off Algorithm
This algorithm runs when a collision created. Detect the Collision

Stop transmitting receiving data

Generate a random Number

Try to communicate after delay X

Ethernet Family
Speed Base band

10 10 10 10/100(present) 100 100 1000(Server) 1000 10000

Base 2 Base 5 Base T Base TX Base T4 Base FX Base TX Base FX Base FX

200-meter 500-meter 100 meter 100 meter 100 meter up to 4 kms 100 meter up to 10 kms

Coaxial cable Thick Coaxial cable Twisted Pair (UTP) UTP UTP 4 Pairs used Fiber Optic UTP Fiber Optic Fiber Optic

Ethernet frame Preamble An alternating 1,0 pattern provides a 5MHz clock at the start of each packet, which allows the receiving devices to lock the incoming bit stream. Start Frame Delimiter (SFD)/Synch The preamble is seven octets and the SFD is one octet (synch). The SFD is 10101011, where the last pair of 1s allows the receiver to come into the alternating 1,0 pattern somewhere in the middle and still sync up and detect the beginning of the data. Length or type 802.3 uses a length field, but the Ethernet frame uses a type field to identify the network layer protocol. 802.3 cannot identify the upper-layer protocol and must be used with a proprietary LAN-IPX, for example

Ethernet Cabling
Coaxial cabling Requirement: T connector, Terminator, BNC connector, Coaxial cable, 10 base2 lan cards

T Connector



Lan card

This is used by BUS topology with 10 mbs Base 2 and Base 5. it is not used currently. UTP Cabling In the UTP, we have used different topology to create the network. (1) Hub / Switch



In any Ethernet UTP topology we have to use one of the two types of cables (1) Straight cable (2) Cross cable TX RX

Structure Cabling Requirement: Rack, patch panel, Switch/ Hub( Rack Mounable), patch cord, I/O connector, I/O box, UTP cable Tool: - Punching tool

Problems of Ethernet technology
(3) (4) (5) (6) In Ethernet only one pc is able to send data at a time, due to this the bandwidth of Ethernet will be shared. Not an equal access technology. One pc will send data, which will be received by the all devices of network. Due to this data communication will not be secured. Collision will occur in the network and collision will lead to other problems like latency, delay and reduce throughput. Latency – time duration to send packet from start to end. Throughput – speed to send data (output) All PCs will have single broadcast domain. Due to this the bandwidth will be reduced.


EMI – Electro Magnetic Indication

LAN Segmentation of Ethernet Network

There are three methods to perform LAN segmentation (1) LAN segmentation using bridge. (2) LAN segmentation using switches. (3) LAN segmentation using Routers.

LAN segmentation using bridge. Existing Hub Hub Hub

New Bridge Port2 Hub Hub Hub



1st collision domain

2nd collision domain

3rd collision domain

1 broadcast domain Working of Bridge: Working of Bridge explains in following steps: (i) Bridge can receives a frame in the buffer memory. (ii) The source MAC address of frame this stored to the bridging table. Port number MAC address 1 2 3 (iii) According to the destination MAC address the frame will be forwarded or drop

(a) If destination MAC address of the frame is known then frame is forwarded to the particular port. (b) If destination MAC address is unknown by bridging table then frame is forwarded to the all port except receiving port. (c) If destination MAC address is broadcast MAC address ff.ff.ff.ff.ff.ff. (d) If destination MAC address exist on the same port from which port received then frame is dropped. Collision domain A group of pc, in which collision can occur, is called a collision domain. Broadcast domain A group of pc in which broadcast message is delivered is called broadcast domain. LAN segmentation using Switches Due to perform Lan segmentation using switches. We have to remove hubs from the network and replace hub with switches the working of switches. The working of switch is exactly like a bridge. A multiport bridge can be used as a bridge.




1 broadcast domain Collision domain = micro segmentation Switch‟s working is same like bridge Advantages: (1) Bandwidth will not be shared and overall throughput will depend on wire speed of the switch. Wire speed is also called switching capacity measured in mbps or gbps. Minimum port on switches = 4 Maximum port on switches = 48 (2) Any time access technology. (3) One to one communication so that network will be more secures. (4) Switches will perform micro segmentation and no collision will occur in network. Lan segmentation using router If we are facing high concession in the n/w due to the large number of broadcast then we can divide broadcast domain of network. So that number of broadcast message will be reduced.

Exist: Switch | Hub Switch | Hub Switch | Hub

New: R

Switch | Hub

Switch | Hub

Switch | Hub

1st Broadcast Domain 2nd Broadcast Domain 3rd Broadcast Domain Router is unicast. We have to install router between multiple switches to divide the broadcast domain. Each broadcast domain has to used different network address and router will provide inter network communication between them. Router operation When a pc has to send data to a different network address, then data will be forwarded to the router. It will analysis IP address of the data and obtain a route from the routing table. According to the route data will be dropped, If route not available. Pc Architecture

Processor Memory controller I/O Controller RAM BIOS ROM HDD CMOS RAM FD CDD

K/B Controller


Display Card Serial Parallel USB Sound Card


Router Architecture LAN I/O Controller Memory Controller RAM




BIOS ROM Incomplete IOS NVRAM Startup Configuration


Non-Volatile RAM

(1) Processor Speed: - 20 MHz to 1GHz

Architecture: - RISC Reduce Instruction set computer Manufacturers: - Motorola, IBM, Power PC, Texas, Dallis, Intel. (2) Flash RAM Flash Ram is the permanent read/write memory. This memory is used to store one or more copies of router o/s. Router o/s is also called IOS (Internetwork Operating System).  Flash Ram stores the only o/s. The size of flash ram in the router is 4mb to 128mb. The flash ram may be available in one of the following three packages: SLMM Flash: - Single Line Memory Module PCMCIA Flash: - Personal Computer Memory Card Interface Architecture Compact Flash: - (Small Memory)

(3) NVRAM NVRAM is a “Non Volatile Random Access Memory”. It is used to store the configuration of the Router. The size of NVRAM is 8 KB to 512 KB. (4) RAM Ram of the router is divided into two logical parts. (i) Primary RAM (ii) Shared RAM Primary RAM Primary RAM is used for: (a) Running copy of IOS. (b) Running configuration (c) Routing table (d) ARP table (IP address to MAC address) (e) Processor & other data structure Shared RAM Shared RAM is used as a buffer memory to shared the data received from different interfaces. Size of ram in a router may vary from 2 mb to 512 mb. The types of memory that may be present in a ram are: (a) DRAM -> Dynamic RAM (b) EDORAM -> Extended Data Out Ram (c) SDRAM -> Synchronous Dynamic Ram (5) BIOS ROM The BIOS ROM is the permanent ROM. This memory is used to store following program & Routines: (i) Boot strap loader (doing booting)

(ii) (iii) (iv)

Power on self test routines Incomplete IOS ROM Monitor (ROM-MON)

Booting difference between router & Pc Router ROM-MON Incomplete IOS FLASH

PC CMOS Setup Bootable Floppy/CD O/S From HDD

Router Interfaces & Ports
Interface is used to connect LAN networks or wan networks to the router. Interface will use protocol stacks to send/receive data. Ports are used for the configuration of routers. Ports are not used to connect different n/ws. The primary purpose of port is the management of router. Router Interfaces Interface Connector Ethernet RJ45 AUI Fast Ethernet Serial DB15 RJ45 DB60

color yellow yellow yellow blue

Speed 10 mbps

Smart Serial BRI ISDN VOIP

SS RJ45 RJ11

blue orange white

Use to connect Ethernet LAN Using UTP media 10 mbps to connect Ethernet LAN Using Trans-Receiver 100 mbps to connect Ethernet LAN E1-2 mbps to connect WAN T1-1.5 mbps Technology like Leased Lines, Radio link, Frame Relay, X.25, ATM “ “ 192 kbps to connect ISDN Basic Rate Interface to connect Phones, Fax, EPABX

AUI – Attachment Unit Interface EPABX – Electronic Private Automatic Branch PSTN – Public Services Telephone Network Router Ports Port





Console Auxiliary

RJ45 RJ45

sky blue black -

9600bps depend on Modem -

Virtual terminal Vty

used for configuration Using PC to connect remote router using PSTN line to connect remote router with telnet protocol via interface

Types of routers:(1) Fixed configuration router (2) Modular router (3) Chassis based router

Other interfaces:(1) Token Ring RJ45 Violet To connect Token Ring network. (2) E1/T1 controller RJ45 White (3) ADSL RJ11 (Asynchronous Digital Subscriber Line) 4/16 mbps E1-2048 kbps T1-1544 kbps up-640 kbps Down-8 mbps

Router Access Modes
When we access router command prompt the router will display different modes. According to the modes, privileges and rights are assigned to the user. User mode In this mode, we can display basic parameter and status of the router we can test connectivity and perform telnet to other devices. In this mode we are not enable to manage & configure router. Privileged mode In this mode, we can display all information, configuration, perform administration task, debugging, testing and connectivity with other devices. We are not able to perform here configuration editing of the router. The command to enter in this mode is „enable‟. We have to enter enable password or enable secret password to enter in this mode. Enable secret has more priority than enable password. If both passwords are configured then only enable secret will work.

Global configuration This mode is used for the configuration of global parameters in the router. Global parameters applied to the entire router. For e.g: - router hostname or access list of router The command enter in this mode is „configure terminal‟. Line configuration mode This mode is used to configure lines like console, vty and auxiliary. There are main types of line that are configured. (i) Console router(config)#line console 0 (ii) Auxiliary router(config)#line aux 0 (iii) Telnet or vty router(config)#line vty 0 4

Interface configuration mode This mode is used to configure router interfaces. For e.g:- Ethernet, Serial, BRI etc. Router(config)#interface <type> <number> Router(config)#interface serial 1 Routing configuration mode This mode is used to configure routing protocol like RIP, EIGRP, OSPF etc. Router(config)#router <protocol> [<option>] Router(config)#router rip Router(config)#router eigrp 10

Configuring Password
There are five types of password available in a router (1) Console Password router#configure terminal router(config)#line console 0 router(config-line)#password <word> router(config-line)#login router(config-line)#exit to erase password do all steps with no command.

(2) Vty Password router>enable router#configure terminal router(config)#line vty 0 4 router(config-line)#password <word> router(config-line)#login router(config-line)#exit (3) Auxiliary Password router#configure terminal router(config)#line Aux 0 router(config-line)#password <word> router(config-line)#login router(config-line)#exit (4) Enable Password router>enable router#configure terminal router(config)#enable password <word> router(config)#exit (5) Enable Secret Password Enable Password is the clear text password. It is stored as clear text in configuration where as enable secret password is the encrypted password with MD5 (Media Digest 5) algorithm. Router>enable Router#configure terminal Router(config)#enable secret <word> Router(config)#exit Encryption all passwords All passwords other than enable secret password are clear text password. We can encrypt all passwords using level 7 algorithm. The command to encrypt all password are Router#configure terminal Router(config)#service password-encryption

Managing Configuration
There are two types of configuration present in a router (1) Startup Configuration (2) Running Configuration (1) Startup configuration is stored in the NVRAM. Startup configuration is used to save settings in a router. Startup configuration is loaded at the time of booting in to the Primary RAM.

(2) Running Configuration is present in the Primary RAM wherever we run a command for configuration, this command is written in the running configuration. To save configuration Router#copy running-configuration startup-configuration Or Router#write To abort configuration Router#copy startup-configuration running-configuration To display running-configuration Router#show running-configuration To display startup configuration Router#show startup-configuration

To erase old configuration Router#erase startup-configuration Router#reload Save[y/n]:n

Access Router using console
Com/Port--------DB9------------------------Console Cisco Console RJ45 Router In windows Click start=> program=> accessories=> comm.(communication)=> hyperterminal Type any name Select com port Set settings Speed 9600 stop bit 1 Data bits 8 Parity no Click ok Press shift+home to default prompt

CISCO command line shortcuts
Tab – to auto complete command ? – To take help Ctrl+P – to recall previous command

Ctrl+N – next command Ctrl+Z – alternate to „end‟ command Ctrl+C – to abort Q – to quit Ctrl+Shift+6 – to break connection

Command line editing shortcuts
Ctrl+A – to move cursor at start of line Ctrl+E – to move cursor at end of line Ctrl+ B – to move cursor one character back Ctrl+F – to move cursor one character forward Ctrl+W – to delete word one by one word back Ctrl+D – to delete one character Ctrl+U – to delete one line Esc+B – to take cursor one word back Esc+F – to take cursor one word forward

Configuring HostName
Router#configure terminal Router#hostname <name> <name>#exit or end or /\z

Configuration Interfaces
Interfaces configuration is one of the most important part of the router configuration. By default, all interfaces of Cisco router are in disabled mode. We have to use different commands as our requirement to enable and configure the interface. Configuring IP, Mask and Enabling the Interface Router#configure terminal Router(config)#interface <type> <no> Router(config-if)#ip address <ip> <mask> Router(config-if)#no shutdown Router(config-if)#exit Interface Numbers Interface numbers start from 0 for each type of interface some routers will directly used interface number while other router will use slot no/port no addressing technique. Eth 0 Serial 0 Serial 1 To configure Interface description Router#configure terminal Slot 1 Serial 1/0 Serial 1/1 Slot 0 Serial 0/0

Router(config)#interface <type> <no> Router(config-if)#description <line> Configuring optional parameter on LAN interface Router#configure terminal Router(config)#interface <type> <no> Router(config-if)#duplex <half|full|auto> Router(config-if)#speed <10|100|auto> Router(config-if)#end Configuring optional parameter on WAN interface Router#configure terminal Router(config)#interfac <type> <no> Router(config-if)#encapsulation <protocol> Router(config-if)#clock rate <value> Router(config-if)#end

To display interface status Router#show interfaces (to show all interfaces) Router#show interface <type> <no> This command will display following parameters about an interface 1) Status 2) Mac address 3) IP address 4) Subnet mask 5) Hardware type / manufacturer 6) Bandwidth 7) Reliability 8) Delay 9) Load ( Tx load Rx load) 10) Encapsulation 11) ARP type (if applicable) 12) Keep alive 13) Queuing strategy 14) Input queue details Output queue details 15) Traffic rate (In packet per second, bit per second) 16) Input packet details 17) Output packet details 18) Modem signals (wan interface only)

19) M.T.U maximum transmission rate (mostly 1500 bytes) Configuring sub interface Sub interface are required in different scenario. For e.g:- in Ethernet we need sub interface for Vlan communication and in frame relay we need sub interface for multipoint connectivity. Sub interface means creating a logical interface from physical interface. Router#config ter Router(config)#interface <type> <no> <subint no> Router(config-subif)# Router(config-subif)#end Router(config)#interface serial 0.2 Configuring secondary IP Router#config terminal Router(config)#interface <type> <no> Router(config-if)#IP address Router(config-if)#IP address secondary Router(config-if)#no shutdown (to enable the interface because they always shutdown) Router(config-if)#exit Router#show run (to display secondary IP)

Managing Command Line History
We can use CTRL+P & CTRL+N shortcuts to display command history. By default router will up to 10 commands. In the command line history, we can use following commands to edit this setting To display commands present in history Router#show history To display history size Router#show terminal To change history size Router#config terminal Router(config)#line console 0 Router(config-if)#history size <value(0-256)> Router(config-if)#exit

Configuring Banners
Banners are just a message that can appear at different prompts according to the type. Different banners are: Message of the day (motd)

This banner appear at every access method Login Appear before login prompt Exec Appear after we enter to the execution mode Incoming Appear for incoming connections Syntax:Router#config terminal Router(config)#banner <type> <delimation char> Text Massage <delimation char> Router(config)# Example:Router#config terminal Router(config)#banner motd $ This router is distribution 3600 router connected to Reliance $ Router(config)#

Configure Login
Router generates the log message, which has stored in the router internal buffer and also displayed on the console. To display log buffer Router#show logging To send log messages to sys log server Router#config ter Router(config)#logging <IP address> Router(config)#exit To configure synchronous logging on console Router#config terminal Router(config)#line console 0 Router(config)#logging synchronous Router(config)#exit syslog server windows->search on google to install syslog server on our pc which creates a file in which we store logging buffer memory on the pc.

Configuring Router Clock
We can configure router clock with the help of two methods. (1) Configure clock locally (2) Configure clock on NTP server (Network Time Protocol) Router does not have battery to save the clock setting. So that clock will reset to the default on reboot. To display clock Router#show clock To configure clock Router#clock set hh:mm:ss day month year 00-23: 00-59:00-59 1-31 JAN-DEC 1993-2035 To configure clock from NTP server Router#config terminal Router(config)#ntp server <IP address> Router(config)#exit C:\>ping To get ntp server ip from internet C:\>route print

Status message of Interfaces
When we use “Show Interfaces” command on router. The first two lines will display the status message. It will display one of the following four messages. Interface is administratively down, line protocol is down. This message means that the interface is shutdown by the administrator using “shutdown” command. We can change this status with help of “no shutdown” command. Interface is up, line protocol is up. This message will appear when everything working fine and interface is able to communicate with other devices. In case of Ethernet, this message will display when interface is connected and enabled. In case of serial, this message will display when end to end connectivity is established. Interface is down, line protocol is down This message will appear when interface is not receiving clock rate. This message will never appear in case of Ethernet. In case of serial, this message may appear due to following reasons. R x-----x--------m x---------------x-------------x m--------------R Fault

Interface is up, line protocol is down This message will appear due to the encapsulation failure. In case of Ethernet, this message may appear when interface is not connected properly. In case of serial, this message may appear due to following R ----------M----------------M------x------x R Fault

e.g:router#show Interface serial 0 router#show Interface eth 0

Router Booting Sources
A router can boot from various sources. By default, it will boot from the flash memory and we can control the sequence with the help of configuration system or commands. A router can boot from following sources: (1) First file in flash (2) Specific file in flash (3) Incomplete IOS (4) TFTP Server (5) Rom Monitor (from Bios) The first to control boot sequence using configuration system register. We can modify configuration register value with the help of “config-register” command in global configuration mode. We can also modify register value from ROM monitor mode. Configuration Register Configuration Register is 16-bit value, which is stored in the NVRAM. At the time of booting the Bootstrap Loader reads the value of configuration Register and according to the value it configure its booting behavior. 0x2102 (IOS with Config) With this value the router will boot from first file present in the flash memory. This is the default value of configuration register. After loading IOS the router will also load startupconfig into running-config. 0x2101 (Incomplete IOS with Config) The router will boot from incomplete IOS and then load the startup-config. 0x2100 (Rom Monitor) With this router will not boot. But enters to the Rom Monitor mode. 0x2142 (IOS without Config) The router will boot from first file in flash. But bypass the startup configuration

0x2141 (Incomplete IOS without Config) The router will boot from Incomplete IOS but bypass the startup-config.

To change Config-Register from global mode Router#configure terminal Router(config)#config-register <value> Router(config)#exit Router#reload Note: - this is the only value, which is configured in the configuration mode and does not need to be saved. To change Config-Register using Rom Monitor Steps: (1) Power on the router (2) Press “ctrl+break” from console with in 60 sec. (3) The router will enter to the Rom Monitor. Type following commands Rom Mon>confreg <value> Rom Mon>i Note: - in 2500 series router “o/r” command should be used in place of “confreg” command. Boot System commands Boot system command is the second method to control sequence of router. These commands will be executed only when configuration register is set to 0x2102. Boot system commands are executed in global configuration mode. These commands are executed in the same sequence they are applied to the router. If one boot system command is successful then next boot system command is not executed in the router. Router(config)#boot system flash <file name> To boot router from specific file in flash Router(config)#boot system tftp <file name> <IP address> To boot router from TFTP server/network Router(config)#boot system flash To boot from first file in flash Router(config)#boot system rom To boot from incomplete IOS

TFTP server
TFTP server is modified form of FTP. It is used to transfer file without performing authentication. TFTP has only home directory, in which subdirectories are not allowed. Directory browsing is not allowed in the home directory. TFTP is the udp-based protocol, which works on port no 69. TFTP has following features in comparison to the FTP. (1) Only get file and put file service is available. (2) Authentication is not supported. (3) Home directory may not have subdirectories (4) Directory browsing is not allowed Installation and Configuration of TFTP server In windows system, we have to execute following steps to use the pc as TFTP server. (1) Download TFTP server software from Internet. (2) Install the TFTP server software on pc. (3) If software is not installed as the service then software should be running on screen. Configure home directory of server or use default.

Functions to be perform with the help of TFTP server (1) To boot router from TFTP server (2) Backup IOS and configuration (3) Restore IOS and configuration (4) Upgrade IOS (1) To boot from TFTP server i) Run the tftp server s/w on pc. And copy IOS image file in the Home directory of tftp server. ii) Test connectivity between router and tftp server. iii) On router use following commands:Router#conf ter Router(config)#boot system tftp c1700-1s-mz.122.3.bin Router(config)#exit Router#copy runn start Reload the device. Make sure that configuration register set as 0x2102. 2) To backup IOS i) Test connectivity and make sure TFTP server is running. ii) Type command: Router#show flash (note the IOS filename) Router#copy flash TFTP Source filename = ? Destination filename=? IP of TFTP server=?

To backup Configuration i) Test connectivity and make sure TFTP server is running. ii) Type commands: Router#copy running-config tftp Or Router#copy startup-config tftp Remote IP: ________ Destination Filename: ______________ 3) To restore Configuration i) Test connectivity and make sure TFTP server is running. ii) Make sure configuration file is present in home directory and note the filename. iii) Type commands: Router#copy tftp running-config Remote IP: __________ Source Filename: _______________ Destination Filename[running-config]: _______________

4) Restore/Upgrade IOS There are four different conditions in which we can restore/upgrade ios. Case 1: old ios is present and flash is in read/write mode. i) Copy ios image in tftp server‟s home directory. ii) Test connectivity and make sure tftp server is running. iii) On router use commands: Router# copy tftp flash Source file: Destination file: IP address: Erase Flash [y/n]: Case2: old ios is present but flash is in read only. i) In this case, we have to set config-register to 0x2101 to boot the router from incomplete ios. ii) After booting the flash will be read/write mode. Now use same command as in condition case 1. iii) When ios loading is complete reset config-register to 0x2102. Case3: old ios is not present but incomplete ios is present in bios. The router will automatically boot from incomplete ios. And we have to execute same commands as in case1 and case2. Case4: complete ios and incomplete ios is not present in router.

There are two methods to load ios with the help of Rom Monitor mode. Method1: loading ios using xmodem In this case we have to use xmodem command and the ios will be loaded with the help of console cable. Tftp is not required in this case. i) Enter to the Rom Monitor and type following command. Rom Mon 1>xmodem <filename> ii) When router display a message “ Ready to receive file” then click on HyperTerminal then Transfer>> Send file>> use browse to select file>> select protocol xmodem>> send. Method2: in this case we have to use tftp server in Rom Monitor. i) Connect the pc tftp server make sure tftp is running and ios image present in the home directory. ii) Enter to the Rom Monitor mode and type following command. Rom Mon>IP_ADDRESS= TFTP_SERVER= TFTP_FILE=<filename> DEFAULT_GATEWAY= IP_SUBNET_MASK= >tftpdnld When ios transfer is completed then type command. Rom Mon>boot Router#show version To view from where ios boot. Router#show flash

Resolving Host Name
In router, we can communicate with the help of IP address as well as host name and domain name. There are two methods to resolve hostname into IP address. 1) Using local hostname database We can use local hostname database by using IP host command. We can use this command with following syntax: Router#config terminal Router(config)#IP host <name> <IP address> Router(config)#IP host abc Router(config)#exit Router#show hosts Router#ping abc 2) Using a DNS server We can configure router to send DNS queries to DNS server. The DNS server will resolve hostname and then pc or router will try to communicate with destination. We can create maximum 6 IP.

Router#config terminal Router(config)#IP name-server <IP> [<IP2>] Router(config)#IP name-server Router(config)#exit

Managing Telnet connection
Our router is able to telnet other devices as well as other devices can also perform telnet to our router. To allow Telnet access to router For this purpose we have to configure IP address, vty password and enable secret password. IP must exist between client and router. When router will be able to perform telnet access. On telnet client we have to use following command: Router#Telnet <IP of router> To display connected users Router#show users To disconnect a user Router#clear line <no>(to view no use show users & show line commands) To telnet a device from router Router#telnet <IP> Or Router>telnet <IP> Or Router><IP> To exit from telnet session Router#exit To exit from a hanged telnet session Ctrl+shft+6 X Router#disconnect To display connected session Router#show sessions This command shows those sessions, which are created or connected by us. If we want anyone can telnet our router without password then on the line vty type command “No Login”.

TCP/IP is the most popular protocol stack, which consist of large no of protocol. According to the OSI model TCP/IP consist of only four layers. TCP/IP model is modified form of DOD (Department of Defense) model. A P S T TCP | UDP Transport (Host to Host) Http Smtp Dns Ftp Tftp Telnet Ntp Snmp Ssl Rdp & many more 80 25 53 20 69 23 123 443 3389 pop3 imap Application

Internet Protocol N ARP| RARP | ICMP | IGMP | RIP | OSPF | BGP Internet

DL All common Lan/Wan Technologies Ph Network Access

Application Layer
This layer contains a large no. of protocols. Each protocol is designed to act as server & client. Some of protocol will need connection oriented. TCP and others may need connection less UDP for data transfer. Application layer use port no.s to identity each application at Transport layer. This layer performs most of functions, which are specified by the Application, Presentation, and Session layer of OSI model.

Transport Layer
Two protocols are available on Transport layer 1) Transmission Control Protocol 2) User Datagram Protocol 1) Transmission Control Protocol TCP performs connection-oriented communication. Its responsibilities are: i) Error Checking ii) Acknowledgement iii) Sequencing iv) Flow Control v) Windowing TCP Header (24 bytes)

Bytes 4

Source port 16 bits ( Randomly generated) (1024) Sequence no. 32 bits (100)

Destination port 16 bits ( Fixed ) (80)

Bytes 4


Acknowledgement no. 32 bits (500)


Header length Reserved 4 bits 6 bits

Code bits 6 bits

Window 16 bits (512 bytes – onwards 1024)

4 4

Checksum 16 bits Options 0 or 32

Urgent 16 bits

Data (varies) 2) User Datagram Protocol UDP is connection less protocol, which is responsible for error checking and identifying applications using port numbers. UDP Header (8 bytes) Bytes 4 4 Source port 16 bits Length 16 bits Data Destination port 16 bits Ckecksum 16 bits

Internet Layer
The main function of Internet layer is routing and providing a single network interface to the upper layers protocols. Upper or lower protocols have not any functions relating to routing. To prevent this, IP provides one single network interface for the upper layer protocols. After that it is the job of IP and the various Network Access protocols to get along and work together. The main protocols are used in Internet layer:1) Internet Protocol (IP) 2) Internet Control Message Protocol (ICMP) 3) Address Resolution Protocol (ARP) 4) Reverse Address Resolution Protocol (RARP)

5) Proxy ARP Internet Protocol This protocol works at internet layer. It is responsible for logical addressing, defining type of service and fragmentation. IP Header (20 – 24 bytes) IP version (4bits) Header length (4) Type of service (8) Total length(16) Flag (3) Protocol (8) Source IP (32) Destination IP (32) Options (0 or 32 bits if any) Segment data Fragmentation offset (13) Header checksum (16)

Identification no (16) Time to live (8)

IP Subnet
In TCP/IP by default three sizes of networks are available: (1) Class A -224 PC -> 16777216 (2) Class B - 216 PC-> 65536 (3) Class C – 28 PC -> 256 In subneting, we will divide class A,B & C network into small size sub networks. This procedure is called subneting. Subneting is performed with the help of subnet mask. There are two types of subneting that we performed: (1) FLSM Fixed Length Subnet Mask (2) VLSM Variable Length Subnet Mask

Why to Sub?
(i) Default Class Network provide us large no. of PCs in comparison to the requirement of PCs in the network. (ii) It is practical never possible to create a class A or class B sized network. To reduce the broadcast of network, we have to perform LAN segmentation of routers. In each sub network, we need different network addresses.

How to Subnet?

In this formula, we will first modify our requirement according to the no. of subnet possible then we calculate new subnet mask and create IP range. Example 1 Class = C No. of subnet =5 Step1 No. of subnet possible is 2,4,8,16,32…… Class= C No. of subnets= 8 Step 2 Calculate key value 2? = No. of subnets 2? = 8 23= 8 Step 3 Calculate new subnet mask In class C Net id 24+key 24+3 27 11111111.11111111.11111111.11100000 255. 255. 255. 224 We add this address to make subnet mask Step 4 Range No. of Pc/Subnet= Total Pc/ No. of Subnet = 256/8 =32 In Class C x.x.x.0 – x.x.x.31 (1)(30) x.x.x.32- x.x.x.63 6495 96127 128159 160191 192223 x.x.x.224-x.x.x.255

Host id 8-key 8-3 5

The first IP of each subnet will be subnet id and last IP will be sub network broadcast address. Example 2 Class= C No. of subnet= 10 Step 1 No. of subnet= 16 Step 2 24= 16 Step 3 Net id Host id 24+4 8-4 11111111.11111111.11111111.11110000

Subneting method 2
Class= No. of Pc/Sub= 8 Mask= ? Range= ? In this case we have to calculate the key according to the no. of per subnet according to the key value the bits of subnet mask from right hand side are set to zero then range is calculated. Example Class= C No. of Pc/Sub=5 Step 1 No. of Pc/Subnet possible 4,8,16,32,64…. New requirement Class= C No. of Pc/Sub= 8 Step 2 2?= No. of Pc/Sub 2?= 8 23= 8 key 3

11111111.11111111.11111111.11111000 255. 255. 255. 248 No. of Subnet= Total Pc/(Pc/Sub) = 256/8 Class C .8 .16 .24 . . Example 2 Class C No. of Pc/Sub=50 Step 1 Class= C No. of Pc/Sub= 64 Step 2 26= 64 11111111.11111111.11111111.11000000 255. 255. 255. 192 Sub 32 .15 .23 .31 Pc/Sub 8

No. of subnet= 256/64= 4 Class C Sub 4 Pc/Sub 64

Method 3
No. of Pc/Sub= 50 New req. No. of Pc/Sub= 64 No. of Subnet= 256/64= 4 Class= C No. of Sub= 4

22= 4 24+2 8-2 11111111.11111111.11111111.11000000 255. 255. 255. 192

Zero Subnet
According to the rules of IP Addressing the first subnet and last subnet is not useable due to routing problem. In new Cisco router a command is present in default configuration. With this command, we are able to use first and last Subnet after Subneting. Command is Router#config ter Router(config)#ip subnet-zero Router(config)#exit Example: - Check whether an address is valid IP, N/w address or Broadcast address. If IP is valid then calculate its N/w & Broadcast address. 28 4


Valid IP


Network address


Broadcast address

Example: Class= B No. of subnet= 64 26= 64 11111111.11111111.11111111.11000000 255. 255. 255. 192 No. of Pc/Sub= 65536/64= 1024 – – –

Prefix Notation of representing IP Address
IP address can be written as IP & Mask as well as IP/Prefix. This method is representing IP address also called CIDR (Classless Inter Domain Routing) notation.

No Subneting
200.100.8.X 200.100.1.X 200.100.7.X 200.100.9.X

200.100.4.X 200.100.5.X

200.100.6.X 200.100.3.X


FLSM 200.100.0-15/28

Remaining Subnet 144 – 159 160 – 175 176 – 191 192 – 207 208 – 223 224 – 239 240 – 255 Problem with FLSM In FLSM, we have to create subnet of equal size. All N/w will be allotted constant size subnet instead of their IP addresses requirement. Due to this a N/w may be allotted more than required IP address and less than required IP addresses.

/25 /26 /27 /28 /29 Sub 2 Pc/Sub 128 Sub 4 Pc/Sub 64 Sub 8 Pc/Sub 32 Sub 16 Pc/Sub 16 Sub 32 Pc/Sub 8

0 – 127 128 – 255

0 – 63 64 – 127 128 – 191 192 – 255

0 – 31 32 – 63 64 – 95 96 – 127

0 – 15 16 – 31 32 – 47 48 – 63 64 –79 80 – 95 96 – 111

0–7 8 – 15 16 – 23 24 - 31

/30 Sub 64 Pc/Sub 4

0–3 4–7 8 – 11 12 – 15

20 32-63/30

30 64-95/27

2 4-7/30 2 8-11/30 5 16-23/29

2 IP 0-3/30 2 12-15/30

10 96-111/28

50 128-191/26

Remaining 24 – 31 112 – 127 If we are using VLSM and Dynamic Routing then routing be compatible to VLSM. This will happen only if Subnet masks are also sends in the routing updates.

Super Netting
Combining small N/w to create a large size N/w is called Super Network. Super netting is mostly used to define route summarizations in routing tables. It is not used for the implementation of large network. 170.00001010.00000000.00000000 170.00001011.00000000.00000000

IP Routing
When we want to connect two or more networks using different n/w addresses then we have to use IP Routing technique. The router will be used to perform routing between the networks. A router will perform following functions for routing. (1) Path determination (2) Packet forwarding

(1) Path determination The process of obtaining path in routing table is called path determination. There are three different methods to which router can learn path. i) Automatic detection of directly connected n/w. ii) Static & Default routing iii) Dynamic routing

(2) Packet forwarding It is a process that is by default enable in router. The router will perform packet forwarding only if route is available in the routing table.

Routing Process
(i) The pc has a packet in which destination address is not same as the local n/w address. (ii) The pc will send an ARP request for default gateway. The router will reply to the ARP address and inform its Mac address to pc. (iii) The pc will encapsulate data, in which source IP is pc itself, destination IP is server, source Mac is pc‟s LAN interface and destination Mac is router‟s LAN interface.





The router will receive the frame, store it into the buffer. When obtain packet from the frame then forward data according to the destination IP of packet. The router will obtain a route from routing table according to which next hop IP and interface is selected (iv) According to the next hop, the packet will encapsulated with new frame and data is send to the output queue of the interface.

Static Routing
In this routing, we have to use IP route commands through which we can specify routes for different networks. The administrator will analyze whole internetwork topology and then specify the route for each n/w that is not directly connected to the router. Steps to perform static routing (1) Create a list of all n/w present in internetwork. (2) Remove the n/w address from list, which is directly connected to n/w. (3) Specify each route for each routing n/w by using IP route command. Router(config)#ip route <destination n/w> <mask> <next hop ip> Next hop IP it is the IP address of neighbor router that is directly connected our router. Static Routing Example: Router#conf ter Router(config)#ip route

Advantages of static routing
(1) Fast and efficient. (2) More control over selected path. (3) Less overhead for router. (4) Bandwidth of interfaces is not consumed in routing updates.

Disadvantages of static routing
(1) More overheads on administrator. (2) Load balancing is not easily possible. (3) In case of topology change routing table has to be change manually.

Alternate command to specify static route
Static route can also specify in following syntax: Old Router(config)#ip route Or Router(config)#ip route serial 0

Backup route or loading static route
If more than one path are available from our router to destination then we can specify one route as primary and other route as backup route. Administrator Distance is used to specify one route as primary and other route as backup. Router will select lower AD route to forward the traffic. By default static route has AD value of 1. With backup path, we will specify higher AD so that this route will be used if primary route is unavailable. Protocols Directly Connected Static BGP EIGRP IGRP OSPF RIP AD 0 1 20 90 100 110 120

Syntax: - To set backup path Router(config)#ip route <dest. n/w> <mask> <next hop> <AD> Or <exit interface> Example: Router#conf ter Router(config)#ip route Router(config)#ip route 8 (below 20) Router(config)#exit

Default Routing
Default routing means a route for any n/w. these routes are specify with the help of following syntax: Router(config)#ip route <next hop> Or <exit interface> This type of routing is used in following scenario. Scenario 1: Stub network A n/w which has only one exit interface is called stub network.


If there is one next hop then we can use default routing. Scenario 2 Internet connectivity On Internet, million of n/ws are present. So we have to specify default routing on our router. Default route is also called gateway of last resort. This route will be used when no other routing protocol is available.


Router(config)#ip route Router(config)#ip route

To display routing table Router#sh ip route To display static routes only Router#sh ip route static To display connected n/ws only Router#sh ip route connected S [1/0] via To check all the interface of a router Router#sh interface brief

Dynamic Routing
In dynamic routing, we will enable a routing protocol on router. This protocol will send its routing information to the neighbor router. This protocol will send its routing information to the neighbor router. The neighbors will analyze the information and write new routes to the routing table. The routers will pass routing information receive from one router to other router also. If there are more than one path available then routes are compared and best path is selected. Some examples of dynamic protocol are: RIP, IGRP, EIGRP, OSPF

Types of Dynamic Routing Protocols
According to the working there are two types of Dynamic Routing Protocols. (1) Distance Vector (2) Link State According to the type of area in which protocol is used there are again two types of protocol: (1) Interior Routing Protocol (2) Exterior Routing Protocol

Autonomous system
Autonomous system is the group of contiguous routers and n/w, which will share their routing information directly with each other. If all routers are in single domain and they share their information directly with each other then the size of routing updates will depend on the no. of n/w present in the Internetwork. Update for each n/w may take 150 – 200 bytes information. For example: - if there are 1000 n/ws then size of update will be 200*1000 = 200000 bytes

The routing information is send periodically so it may consume a large amount of bandwidth in our n/w. Border Routing Exterior Routing

Interior Routing AS 200 Domain AS 400 AS 500

Interior Routing RIP IGRP EIGRP OSPF Exterior Routing BGP EXEIGRP

Distance Vector Routing
The Routing, which is based on two parameters, that is distance and direction is called Distance Vector Routing. The example of Distance Vector Routing is RIP & IGRP. Operation: (1) Each Router will send its directly connected information to the neighbor router. This information is send periodically to the neighbors. (2) The neighbor will receive routing updates and process the route according to following conditions: (i) If update of a new n/w is received then this information is stored in routing table. (ii) If update of a route is received which is already present in routing table then route will be refresh that is route times is reset to zero. (iii) If update is received for a route with lower metric then the route, which is already present in our routing table. The router will discard old route and write the new route in the routing table. (iv) If update is received with higher metric then the route that is already present in routing table, in this case the new update will be discard.

(3) A timer is associated with each route. The router will forward routing information on all interfaces and entire routing table is send to the neighbor. There are three types of timers associated with a route. (i) Route update timer It is the time after which the router will send periodic update to the neighbor. (ii) Route invalid timer It is the time after which the route is declared invalid, if there are no updates for the route. Invalid route are not forwarded to neighbor routers but it is still used to forward the traffic. (iii) Route flush timer It is the time after which route is removed from the routing table, if there are no updates about the router.

Metric of Dynamic Routing
Metric are the measuring unit to calculate the distance of destination n/w. A protocol may use a one or more than one at a time to calculate the distance. Different types of metric are: (1) Hop Count (2) Band Width (3) Load (4) Reliability (5) Delay (6) MTU Hop Count It is the no. of Hops (Routers) a packet has to travel for a destination n/w. Bandwidth Bandwidth is the speed of link. The path with higher bandwidth is preferred to send the data. Load Load is the amount of traffic present in the interface. Paths with lower load and high throughput are used to send data. Reliability Reliability is up time of interface over a period of time. Delay Delay is the time period b/w a packet is sent and received by the destination. MTU Maximum Transmission Unit It is the maximum size of packet that can be sent in a frame mostly MTU is set to 1500.

Problems of Distance Vector
There are two main problems of distance vector routing (1) Bandwidth Consumption (2) Routing Loops Bandwidth Consumption The problem of accessive bandwidth consumption is solved out with the help of autonomous system. It exchanges b/w different routers. We can also perform route summarization to reduce the traffic. Routing Loops It may occur b/w adjacent routers due to wrong routing information. Distance Vector routing is also called routing by Rumor. Due to this the packet may enter in the loop condition until their TTL is expired.

Method to solve routing loops
There are five different methods to solve or reduce the problem of routing loop. (1) Maximum Hop Count (2) Flash Updates/Triggered Updates (3) Split Horizon (4) Poison Reverse (5) Hold Down Maximum Hop Count This method limits the maximum no. of hops a packet can travel. This method does not solve loop problem. But it reduce the loop size in the n/w. Due to this method the end to end size of a n/w is also limited. Flash Updates/Triggered Updates In this method a partial update is send to the all neighbors as soon as there is topology change. The router, which receives flash updates, will also send the flash updates to the neighbor routers. Split Horizon Split Horizon states a route that update receive from an interface can not be send back to same interface. Poison Reverse This method is the combination of split Horizon and Flash updates. It implements the rule that information received from the interface can not be sent back to the interface and in case of topology change flash updates will be send to the neighbor. Hold Down If a route changes frequently then the route is declared in Hold Down state and no updates are received until the Hold Down timer expires.

Routing Information Protocol
Features of RIP: * Distance Vector * Open standard * Broadcast Updates ( * Metric Hop Count *Timers Update 30 sec Invalid 180 sec Hold 180 sec Flush 240 sec * Loop Control Split Horizon Triggered Updates Maximum Hop Count Hold Down * Maximum Hop Count 15 * Administrative Distance 120 * Equal Path Cost Load Balancing * Maximum Load path 6 Default 4 * Does not support VLSM * Does not support Autonomous system

Configuring RIP Router#conf ter Router(config)#router rip Router(config-router)#network <own net address> Router(config-router)#network <own net address> --------------------------Router(config-router)#exit R1

Router(config-router)#network Router(config-router)#network Router(config-router)#network via Display RIP Routers Router#sh ip route rip R [120/5] via 00:00:25 serial 1/0 RIP Dest. n/w mask AD Metric Next Hop Timer own Interface RIP advanced configuration Passive Interfaces An interface, which is not able to send routing updates but able to receive routing update only is called Passive Interface. We can declare an interface as passive with following commands: Router#conf ter Router(config)#router rip Router(config-router)#Passive-interface <type> <no> Router(config-router)#exit Neighbor RIP In RIP, by default routing updates are send to the address In some scenarios, it may be required to send routing updates as a unicast from router to another. In this case, we have to configure neighbor RIP. For example: - in a Frame Relay n/w the broadcast update is discarded by the switches, so if we want to send RIP updates across the switches then we have to unicast updates using Neighbor RIP. Frame Relay Cloud

Unicast R1 R2

R1 Router(config)#router rip Router(config-router)#neighbor

R2 Router(config)#router rip Router(config-router)#neighbor

Configuring Timers Router(config)#router rip Router(config-router)#timers basic <update> <invalid> <hold down> <flush> Router(config-router)#exit Example: Router(conf)#timer basic 50 200 210 300 Update 50 sec Invalid 200 sec Hold 210 sec Flush 300 sec To change Administrative Distance Router(config)#router rip Router(config-router)#distance <value> Router(config-router)#exit 95 or 100 To configure Load Balance RIP is able to perform equal path cost Load Balancing. If multiple paths are available with equal Hop Count for the destination then RIP will balance load equally on all paths. Load Balancing is enabled by default 4 paths. We can change the no. of paths. It can use simultaneously by following command: Router(config)#router rip Router(config-router)#maximum-path <1-6> To display RIP parameters Router#sh ip protocol Or Router#sh ip protocol RIP This command display following parameters: (i) RIP Timers (ii) RIP Version (iii) Route filtering (iv) Route redistribution (v) Interfaces on which update send (vi) And receive (vii) Advertise n/w

(viii) Passive interface (ix) Neighbor RIP (x) Routing information sources (xi) Administrative Distance

RIP version 2
RIP version 2 supports following new features: (1) Support VLSM (send mask in updates) (2) Multicast updates using address (3) Support authentication Commands to enable RIP version 2 We have to change RIP version 1 to RIP version 2. Rest all communication will remain same in RIP version 2. Router(config)#Router RIP Router(config-router)#version 2 Router(config-router)#exit To debug RIP routing Router#debug ip rip To disable debug routing Router#no debug ip rip Or Router#no debug all Or Router#undebug all

Interior Gateway Routing Protocol
Features: * Cisco proprietary * Distance vector * Timers Update 90 sec Invalid 270 sec Hold time 280 sec Flush 630 sec * Loop control All methods * Max hop count 100 upto 255 * Metric (24 bit composite) Bandwidth (default) Delay (default) Load Reliability

MTU * Broadcast updates to address * Unequal path cost load balancing * Automatic route summarization * Support AS * Does not support VLSM

Configuring IGRP
Router(config)#router igrp <as no>(1 – 65535) Router(config-router)#network <net address> Router(config-router)#network <net address> Router(config-router)#exit Configuring Bandwidth on Interface for IGRP By default the router will detect maximum speed of interface and use this value as the bandwidth metric for IGRP. But it may be possible that the interfaces and working at its maximum speed then we have to configure bandwidth on interface, so that IGRP is able to calculate correct method. Router(config)#interface <type> <no> Router(config-if)#bandwidth <value in kbps> Router(config-if)#exit Router(config)#interface serial 0 Router(config-if)#bandwidth 256 Router(config-if)#exit

Serial E1


Serial E1

2048 k 256 k sync

2048 k

Configuring Unequal path cost load balancing To configure load balancing, we have to set two parameters (1) Maximum path (by default 4) (2) Variance (default 1) Maximum Path: - it is maximum no. of paths that can be used for load balancing simultaneously.

Variance: - it is the multiplier value to the least metric for a destination n/w up to which the load can be balanced. Router(config)#Router igrp <as no> Router(config-router)#variance <value> Router(config-router)#exit Configuring following options in IGRP as same as in case of RIP: (1) Neighbor (2) Passive interface (3) Timer (4) Distance (AD) (5) Maximum path

Link State Routing
This type of routing is based on link state. Its working is explain as under (1) Each router will send Hello packets to all neighbors using all interfaces. (2) The router from which Hello reply receive are stored in the neighborship table. Hello packets are send periodically to maintain the neighbor table. (3) The router will send link state information to the all neighbors. Link state information from one neighbor is also forwarded to other neighbor. (4) Each router will maintain its link state database created from link state advertisement received from different routers. (5) The router will use best path algorithm to store the path in routing table.

Neighbor Topology R1 dc dc dc R2 R3 R4 R5

Routing R6 R5






Problems of Link State Routing The main problems of link state routing are: (1) High bandwidth consumption. (2) More hardware resources required that is processor and memory (RAM) The routing protocols, which use link state routing are: (1) OSPF (2) EIGRP Enhanced Interior Gateway Routing Protocol Features: * Cisco proprietary * Hybrid protocol Link State Distance Vector * Multicast Updates using Address

* Support AS * Support VLSM * Automatic Route Summarization * Unequal path cost load balancing * Metric (32 bit composite) Bandwidth Delay Load Reliability MTU * Neighbor Recovery * Partial updates * Triggered updates * Backup Route * Multi Protocol Routing

EIGRP Protocols & Modules (1) Protocol depended module This module is used to perform multi protocol routing that is the router will maintain 3 routing table for TCP/IP, IPX/SPX and Appletalk.

IP Routing TCP/IP

Packet type?


IPX Routing


Appletalk Routing

Reliable Transport Protocol (Quiet Protocol) RTP is used to exchange routing updates with neighbor routers. It will also maintain neighbor relationship with the help of Hello packet. RTP has following features: (1) Multicast updates ( (2) Neighbor recovery If neighbor stops responding to the Hello packets then RTP will send unicast Hello packet for that neighbor. (3) Partial updates (4) No updates are send if there is no topology change. Diffusing Update Algorithm (DUAL) DUAL is responsible for calculating best path from the topology table. Dual has following features: * Backup Path * VLSM * Route queries to neighbor for unknown n/w. Configuring EIGRP Router(config)#router eigrp <as no> Router(config-router)#network <net addr.> Router(config-router)#network <net addr.> Router(config-router)#exit Advanced Configuration EIGRP Configuring following options are same as configuring IGRP (1) Bandwidth on Interfaces (2) Neighbor (3) Load balancing Max path Variance Configuring EIGRP Metric If we want our router to use additional metric then we can use following command: Router(config)#Router eigrp <as no> Router(config-router)#metric weights 0 <k1> <k2> <k3> <k4> <k5> Type of service (default) 1 Router(config-router)#exit 0 1 0 0

Metric Bandwidth Load Delay Reliability MTU

K K1 K2 K3 K4 K5

Default value 1 0 1 0 0

All routers exchanging update with each other must have same AS no. and same K value. To up the Ethernet without connect wire Router(config)#int eth0 Router(config-if)#no keepalive Router(config-if)#bandwidth 64

Router#clear ip route * Hush routing table and again make it. Router#sh ip eigrp topology It shows topology database. P-> passive->stable A->active->under updation Router#sh ip eigrp neighbor It shows neighbor table Router#redistribute <protocol> ? Metric also need to be modified Debug IGRP Router#debug ip igrp events Its display info. On special event Router#debug ip igrp transactions It shows every update Debug EIGRP Router#debug ip eigrp For full debug Router#debug ip eigrp summary For few debug

Open Shortest Path First
Features: * Link State

* Open standard * Multicast updates * Support VLSM * Support Area similar to AS * Manual Route Summarization * Hierarchical model * Metric Bandwidth * Equal path cost load balancing * Support authentication * Unlimited hop count OSPF Terminology Already known topics in this: (1) Hello packets (2) LSA (Link State Advertisement) (3) Neighbor (4) Neighbor table (5) Topology table (LSA database) Router ID Router ID is the highest IP address of router interfaces. This id is used as the identity of the router. It maintaining stale databases. The first preference for selecting router ID is given to the Logical interfaces. If logical interface is not present then highest IP of physical interface is selected as router id.

Highest ip is router id of a router

Area Area is the group of routers & n/ws, which can share their routing information directly with each other.

Adjacency A router is called adjacency when neighbor relationship is established. We can also say adjacency relationship is formed between the routers.

OSPF Hierarchical Model
br br

Area 0












Area 20 Area 70 Area 90 Area Router A router, which has all interfaces member of single area, is called area router. Backbone Area Area 0 is called backbone area. All other areas must connect to the backbone area for communication. Backbone Router A router, which has all interfaces members of area 0, is called backbone router. Area Border Router A router, which connects an area with area 0, is called area border router. LSA Flooding in OSPF If there are multiple OSPF routers on multi access n/w then there will be excessive no. of LSA generated by the router and they can choke bandwidth of the network.














This problem is solved with the help of electing a router as designated router and backup designated router. Designated Router A router with highest RID (router id) will be designated router for a particular interface. This router is responsible for receiving LSA from non-DR router and forward LSA to the all DR router. Backup Designated Router This router will work as backup for the designated router. In BDR mode, it will receive all information but do not forward this information to other non-DR router. Commands to configure OSPF Router#conf ter Router(config)#router ospf <process no> Router(config-router)#network <net address> <wild mask> area <area id> Router(config-router)#network <net address> <wild mask> area <area id> Router(config-router)#exit Wild Mask – Complement of subnet mask Example - Subnet mask

Wild mask - subnet mask wild mask

Area 20


Router(config)#router ospf 32 Router(config-router)#network area 20 Router(config-router)#network area 20 Router(config-router)#exit

Area 0

R1 R2

R1 Router(config)#router ospf 33 Router(config-router)#network area 0 Router(config-router)#network area 0 Router(config-router)#exit R2 Router(config)#router ospf 2 Router(config-router)#network area 0 Router(config-router)#network area 0 Router(config-router)#exit R1 R2 R3

R1 Router(config-router)#network Router(config-router)#network R2 Router(config-router)#network Router(config-router)#network Router(config-router)#network R3 Router(config-router)#network Router(config-router)#network

Configuring bandwidth on interface If the actual bandwidth of interface is not equal to the maximum speed of interface then we have to use bandwidth command to specify the actual bandwidth. Router(config)#interface <type> <no>

Router(config-if)#bandwidth <speed> Configuring logical interface for OSPF By default the highest IP address of interface will be elected as Router id. If there is a change in status of interface then router will reelect some IP as Router id. So if we create logical interface, it will never go down and first preference give to the logical interface for RID. Command: Router(config)#interface loopback <no> Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Command to display OSPF parameter Router#show ip protocol Router#show ip ospf Router#show ip ospf neighbor Router#show ip ospf database (it shows RID of router) Router#show ip ospf interfaces

LAN Switching
Ethernet switches are used in LAN to create Ethernet n/ws. Switches forward the traffic on the basis of MAC address. Switches maintain a switching table in which mac addresses and port no.s are used to perform switching decision. Working of bridge and switch is similar to each other.

Classification of switches
Switches are classified according to the following criteria: Types of switches based on working (1) Store & Forward This switch receives entire frame then perform error checking and start forwarding data to the destination. (2) Cut through This switch starts forwarding frame as soon as first six bytes of the frame are received. (3) Fragment-free This switch receives 64 bytes of the frame, perform error checking and then start forwarding data. (4) Adaptive cut-through

It changes its mode according the condition. If it see there are errors in many frames then it changes to Store & Forward mode from Cut through or Fragment-free. Types of switches based on management (1) Manageable switches (2) Non-Manageable switches (3) Semi-Manageable switches Types of switches based on OSI layer (1) Layer 2 switches (only switching) (2) Layer 3 switches (switching & routing) Types of switches based on command mode (only in Cisco) (1) IOS based (2) CLI based Type of switches based on hierarchical model (1) Core layer switches (2) Distribution layer switches (3) Access layer switches

Qualities of switch - No. of ports - Speed of ports - Type of media - Switching or wire speed or throughput

Basic Switch Administration
IOS based switches are similar to the routers. We can perform following function on switches in a similar manner as performed on router. (1) Access switch using console (2) Commands to enter & exit from different mode (3) Commands to configure passwords (4) Manage configuration (5) Backup IOS and configuration (6) Configuring and resolving hostnames (7) Managing telnet (8) Configuring CDP (9) Configuring time clock (10) Configuring Banners (11) Command line shortcuts and editing shortcuts (12) Managing history (13) Configure logging (14) Boot system commands

Following function and options are not similar in router and switch. (1) Default hostname is „Switch‟ (2) Auxiliary port is not present (3) VTY ports are mostly 0 to 15 (4) By default interfaces are enabled (5) IP address cannot be assign to interfaces (6) Routing configuration mode is not present (7) Interface no. starts from 1 (8) Web access is by default enabled (9) Configuration registry is not present in similar manner (10) Flash memory may contain multiple files and startup-configuration is also saved in flash

Configuring IP and Gateway on switch
We can configure IP address on switch for web access or telnet IP address is required for the administration of the switch. If we have to access switch from remote n/w then we will configure default gateway in addition to IP address. IP address is assigned to the logical interface of switch with following command:Switch(config)#interface vlan 1 Switch(config)#IP address <ip> <mask> Switch(config)#no sh Switch(config)#exit Old Switches Switch(config)#ip address <ip> <mask> Switch(config)#exit Configuring Gateway Switch(config)#ip default-gateway <ip> Switch(config)#exit Breaking Switch Password (1) Power off switch press mode button present in front of switch then power on the switch. (2) Keep mode button press until „Switch:‟ prompt appears on console. (3) In switch monitor mode, type following commands: flash_init load_helper rename flash:config.text flash:<anyname> dir flash: boot (4) After booting switch will prompt to enter in initial configuration dialog. Enter „no‟ here and type. Switch>enable Rename flash:<anyname> Flash:config.text

Configure memory Change password and save config. Then copy run strat_config.

Cisco Hierarchal Model
When we want to create a large sized LAN network then we may face following problems if we are going design the network in flat model. (1) High latency (2) Conjunction between switches between switches (3) Large broadcast domain Cisco hierarchal model recommends three layer design of the network (i) Core layer (ii) Distribution layer (iii) Access layer on each layer there are some rules which we have to follow (1) Highest performance devices are connected on Core layer (2) Resources should be placed on Core layer (3) Polices should not be applied on core layer (4) On distribution layer, we can implement policies (5) Distribution and Core devices should be connected with high-speed links. (6) Access layer devices are basic devices and may be non manageable.






100 MBps Accesss Accesss Accesss Accesss Point

(Hierarchal model) After using hierarchal model the most of LAN problem will be solve but one problem still remain same that is all pc s will be in single broadcast domain. We have to implement following solution for this problem. (1) Physical Segmentation (2) Logical Segmentation VLAN Trunking VTP Inter VLAN Pruning Logical Segmentation of Network To perform logical segmentation, we have to create VLAN in the network. With the help of VLAN, we can logically divide the broadcast domain of the network.

VLAN (Virtual LAN)
VLAN provides Virtual Segmentation of Broadcast Domain in the network. The devices, which are member of same Vlan, are able to communicate with each other. The devices of different Vlan may communicate with each other with routing. So that different Vlan devices will use different n/w addresses. Vlan provides following advantages: (1) Logical Segmentation of network (2) Enhance network security Creating port based Vlan In port based Vlan, first we have to create a Vlan on manageable switch then we have to add ports to the Vlan. Commands to create Vlan Switch#config ter

Switch(config)#vlan <no> [name <word>] Switch(config)#exit optional Or Switch#vlan database Switch(vlan)#vlan <no> [name <word>] Switch(vlan)#exit Commands to configure ports for a Vlan By default, all ports are member of single vlan that is Vlan1. we can change vlan membership according to our requirement. Switch#conf ter Switch(config)#interface <type> <no> Switch(config-if)#switchport access vlan <no> Switch(config-if)#exit Commands to configure multiple ports in a vlan Switch#conf ter Switch(config)#interface range <type> <slot/port no (space)–(space) port no> Switch(config-if)#switchport access vlan <no> Switch(config-if)#exit Example: - Suppose we want to add interface fast Ethernet 0/10 to 0/18 in vlan5 Switch#config ter Switch(config)#interface range fastethernet 0/10 – 18 Switch(config-if)#switchport access vlan 5 Switchconfig-if#exit In 1900 & Compatible switches Switch#config ter Switch(config)#interface <type> <no> Switch(config-if)#vlan-membership static <vlan no> Switch(config-if)#exit To Disable web access in switch Switch#config ter Switch(config)#no ip http server To display mac address table Switch#sh mac-address-table Vlan 20 Mac address 00-08-a16-ab-6a-7b type dynamic ports fa0/7

To Display Vlan and port membership Switch#sh vlan

When there are multiple switches then we have to use trunk links to connect one switch with other. If we are not using trunk links then we have to connect one cable from each vlan to the corresponding vlan of the other switch. Normal: Vlan 1 7 3 1 3 7

In Trunking: -

Vlan 1,3,7









Switches will perform trunking with the help of frame tagging. The trunk port will send data frames by adding a Vlan id information to the frame, at the receiving end vlan id information is removing from the end and according to the tag data is delivered to the corresponding vlan. There are two protocols to perform frame tagging. (1) Inter switch link (cisco prop) (2) IEEE 802.1 q Configuring Trunking In cisco switches all switch ports may be configured in three modes (1) Trunk desirable (default) (2) Trunk on (3) Trunk off Switch#conf ter Switch(config)#interface <type> <no> Switch(config-if)#switchport mode <trunk|access|auto> Switch(config-if)#exit on off desirable

To configure Vlans allowed on Trunk By default all Vlans are allowed on Trunk port. We can add/remove a partucular Vlan from trunk port with following command Switch#config ter Switch(config)#interface <type> <no> Switch(config-if)#switchport trunk allowed vlan all Remove <vlan> Add <vlan> Except <vlan> To display trunk interfaces Switch#sh interface trunk Switch#sh interface <type> <no> trunk

Vlan Trunking Protocol (VTP)
With the help of VTP, we can simplify the process of creating Vlan. In multiple switches, we can configure one switch as VTP server and all other switches will be configured as VTP client. We will create Vlans on VTP server switch. The server will send periodic updates to VTP client switches. The clients will create Vlans from the update received from the VTP server. VTP server VTP server is a switch in which we can create, delete or modify Vlans. The server will send periodic updates for VTP clients. VTP client On VTP client, we are not able to create, modify or delete Vlans. The client will receive and forward vtp updates. The client will create same Vlans as defined in vtp update. VTP Transparent Transparent is a switch, which will receive and forward VTP update. It is able to create, delete and modify Vlans locally. A transparent will not send its own VTP updates and will not learn any information from received vtp update. VTP Domain VTP password VTP server Vlan 1,3,5,10,20

Vlan 1,3,5,10,20



Client Vlan 1,3,10,20,40,90





VTP Transparent

Commands Switch#conf ter Switch(config)#vtp domain <name> Switch(config)#vtp password <word> Switch(config)#vtp mode <server|client|transparent> Switch(config)#exit By default in cisco switches the VTP mode is set as VTP server with no domain and no password. To display VTP status Switch#sh vtp status

VTP Pruning
Pruning is the VTP feature through which a trunk link can be automatically disable, for a particular Vlan if neighbor switch does not contain ports in that Vlan. Vlan1 is not prun eligible. Command to configure VTP Pruning We have to use only one command on VTP server for VTP Pruning. Switch#conf ter Switch(config)#vtp pruning Switch(config)#exit Server Vlan 1,3,5,7

Client Vlan 1 3 5 7

Client 1 3 5 7 1

Client 3 5 7

Inter Vlan Communication
After creating Vlans, each Vlan has own broadcast domain. If we want communication from one Vlan to another Vlan then we need to perform routing. There are three methods for inter vlan communication. (1) Inter Vlan using multi-interface router (2) Inter Vlan using router on a stick method (3) Inter Vlan using layer 3 switch 1751, 2621 routers supports Vlan (1) Inter Vlan using multi-interface router In this case, we have to connect one interface of router in each Vlan. This interface will act as gateway for the corresponding vlan. Each Vlan has to use different n/w addresses. Data from one Vlan to another Vlan will travel by router.

Router E0 E1 E2

Vlan1 T 1, 3, 5 1 3 5

Vlan3 T

Vlan5 T

1 3 5




N/w 10.x.x.x 11.x.x.x 12.x.x.x Gateway (2) Inter Vlan using router on a stick method In this method a special router is used for Inter Vlan. In this router, we can create one interface for each Vlan. The physical interface of router will be connected on trunk port switch. This router will route traffic on the same interface by swapping vlan id information with the help of frame tagging protocol.


Fa 0/0

Fa 0/0.1 – -> Vlan1 Fa 0/0.2 – -> Vlan3 Fa 0/0.3 – -> Vlan5


Trunk T

Vlan 1, 3, 5 T

T 1 3 5 1

T 3 5 1

T 3 5

N/w 10.x.x.x Gateway



Configuration on Router Router#config ter Router(config)#interface fastethernet 0/0 Router(config-if)#no ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#interface fastethernet 0/0.1 Router(config-if)#encapsulation dot1q 1 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#interface fastethernet 0/0.2 Router(config-if)#encapsulation dot1q 3 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#interface fastethernet 0/0.3 Router(config-if)#encapsulation dot1q 5 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Configuration on Core switch (1) Configure switch as VTP server (2) Create Vlans (3) Configure interface connected to router as Trunk (4) Configure interfaces connected to other switches as trunk (if required)

Configuration on Distribution layer switches (1) Configure switch as VTP client (2) Configure required interface as Trunk (optional) (3) Add ports to Vlan Configuration on Pc Configure IP and Gateway

Spanning Tree Protocol
When we connect multiple switches with each other and multiple path exist from one switch to another switch then it may lead to the switching loop in the network. Multiple paths are used to create redundancy in the network. STP is only required when multiple path exist then there is possibility of loop in n/w. Packets Switch Switch Switch

Problems the occur with redundancy path (1) Multiple copies of the frame will be received by destination. (2) Frequent changes in the mac address table of switch. (3) A mac address may appear at multiple ports in a switch. (4) Packets may enter in the endless loop. Spanning Tree Protocol will solve this problem by blocking the redundancy interface. So that only one path will remain active in the switches. If the primary path goes down then disabled link will become enable and data will be transferred through that path. Working of STP The STP will create a topology database in which one switch will be elected as Route switch. Path cost is calculated on the basis of bandwidth. The lowest path cost link will be enable mode and another path will be disable.

Route Switch 1 Gb Switch 1 Gb Switch

100 Mb Switch 100 Mb

100 Mb Switch

Lowest cost (Disable) STP terminology (1) Bridge id It is the combination of bridge priority and base mac address. In Cisco switches default priority no. is 32768. (2) Route Bridge The Bridge/Switch with lowest Bridge id will become the Route Bridge. Route Bridge is used as the center point for calculating path cost in topology. (3) BPDU Bridging Protocol Data Units It is the STP information, which is exchange between the switches to create topology and path selection. (4) STP port mode An STP is enabled a port may be in one of the following mode. (i) Listening: - in this mode a port will send/receive BPD. (ii) Learning: - a port will learn mac address table. (iii) Forwarding: - the port will forward data based on mac address table. (iv) Blocking: - the port is block to send/receive data by Spanning Tree Protocol. (v) Disable: - the port is administratively disabled. Path cost calculation The links in switches will be enable or disabled on the basis of path cost. The path cost for each link is calculated according to following table. Old IEEE Cost 100 10 1 1 New IEEE Cost 100 19 4 2

Speed 10 Mb 100 Mb 1 Gb 10 Gb

To configure ports for forwarding mode directly Switch#config ter Switch(config)#interface <type> <no> Switch(config-if)#switchport host

Configuring port security In manageable switches, we can restrict the no. of mac addresses that a port can learn. Even we can specify the mac address statically with a command. With port security, we can also specify the action to be perform if port security violation is detected. Switch#conf ter Switch(config)#interface <type> <no> Switch(config-if)#switchport port-security Switch(config-if)#switchport port-security maximum <no. of mac> Switch(config-if)#switchport port-security violation <shutdown|restrict|reject> Switch(config-if)#switchport port-security mac-address sticky Switch(config-if)#switchport port-security mac-address sticky <mac address> Switch(config-if)#exit

Access Control List
ACL are the basic security feature that is required in any network to control the flow of traffic. Most of time our network may have servers and clients for which traffic control is required. We can also use ACL to classify the traffic. ACLs are used in features like QOS (Quality of Service), Prioritize traffic and interesting traffic for ISDN. Classification Access Control List: Types of ACL based on Protocol: (1) IP Access Control List (2) IPX Access Control List (3) Appletalk Access Control List Types of ACL based on Feature: (1) Standard ACL (2) Extended ACL Types of ACL based on Access mode: (1) Numbered ACL (2) Named ACL Types of ACL based on Order of rules: (1) Deny, permit (2) Permit, deny Types of ACL based on direction of implementation: (1) Inbound ACL (2) Outbound ACL Flow chart of Inbound ACL

A Packet is received

Is there any Access-list applied on interface in Inbound direction?


The packet is passed to Routing Engine


Is there any macthing rule in ACL from topdown order?


The packet is dropped.


The packet is passed to RE


Is it permit?


The packet is dropped.

IP Standard ACL (Numbered) In Standard ACL, we are only able to specify source address for the filtering of packets. The syntax to create IP standard ACL are: Router#conf ter Router(config)#access-list <no> <permit|deny> <source> Router(config)#exit <source> Single pc host

N/w Subnet



Example: - – 18 should not access Internet; rest of all other pc should access Internet.



172.16.x.x Router#conf ter Router(config)#access-list 30 deny Router(config)#access-list 30 deny Router(config)#access-list 30 deny Router(config)#access-list 30 permit any Router(config)#exit Applying ACL on interface Router#conf ter Router(config)#interface <type> <no> Router(config-if)#ip access-group <ACL no.> <in|out> Router(config-if)#exit Rule for applying ACL Only one ACL can be applied on each interface, in each direction for each protocol. Example: - Suppose we want to allow Internet only for – 70.



Router(config)#access-list 25 permit 0.0..31 Router(config)#access-list 25 permit Router(config)#access-list 25 permit Router(config)#access-list 25 permit Router(config)#access-list 25 permit Router(config)#interface serial 0 Router(config-if)#ip access-group 25 out IP Standard ACL (Named) In Numbered ACL editing feature is not available that is we are not able to delete single rule from the ACL. In Named ACL editing feature is available. Router#config ter Router(config)#ip access-list standard <name> Router(config-std-nacl)#<deny|permit> <source> Router(config-std-nacl)#exit Router#conf ter Router(config)#ip access-list standard abc Router(config-std-nacl)#deny Router(config-std-nacl)#deny Router(config-std-nacl)#deny Router(config-std-nacl)#permit any Router(config-std-nacl)#exit To modify the ACL Router#conf ter Router(config)#ip access-list standard abc Router(config-std-nacl)#no deny Router(config-std-nacl)#exit To control Telnet access using ACL If we want to control telnet with the help of ACL then we can create a standard ACL and apply this ACL on vty port. The ACL that we will create for vty will be permit – deny order.

Example: - suppose we want to allow telnet to our router from & pc. Router#conf ter Router(config)#access-list 50 permit Router(config)#access-list 50 permit Router(config)#access-list 50 deny any Router(config)#line vty 0 4 Router(config-line)#access-class 50 in Router(config)#exit

IP Extended ACL (Numbered)
Extended ACL are advanced ACL. ACL, which can control traffic flow on the basis of five different parameters that are: (i) Source address (ii) Destination address (iii) Source port (iv) Destination port (v) Protocol (layer 3/layer 4) The syntax to create Extended ACL Router#conf ter Router(config)#access-list <no> <deny|permit> <protocol> <source> [<s.port>] <destination> [<d.port>] router(config)#exit <no> <protocol> -> -> 100 to 199 layer ¾ IP TCP UDP ICMP IGRP no (1 to 65535) or telnet/www/ftp etc. Single pc host N/w Subnet All Any

<Source port> <Destination port> <Source> <Destination>

Example rules of Extended ACL Router(config)#access-list 140 deny ip any (All tcp/ip data is denied from source to any destination) Router(config)#access-list 120 permit ip any any (All tcp/ip data permit from any source to any destination) Router(config)#access-list 145 deny tcp any host (All tcp data is denied from any source to host Router(config)#access-list 130 permit tcp any host eq 80 (All tcp based data from any source is allowed to access destination on port no. 80 that is www(http) ) – web access Router(config)#access-list 130 permit udp any host eq 53 (Any pc is able to access our DNS service running on port no. 53) Router(config)#access-list 150 deny tcp any any eq 23 [or telnet] (Telnet traffic is not allowed) Router(config)#access-list 160 deny icmp any any (All icmp data from any source to any destination is denied) To display ACL Router#show access-lists or Router#show access-list <no> To display ACL applied on interface Router#show ip interface Router#show ip interface <type> <no> Router#show ip interface Ethernet 0 Example: - Extended ACL Suppose we want to control inbound traffic for our network. ACL should be designed according the following policy. (1) Access to web server ( is allowed from any source. (2) FTP server ( should be accessible only from branch office n/w ( (3) ICMP & Telnet should be allowed only from remote pc (4) Any pc can access DNS (

200.100.175.x Router


200.100.100.x Router(config)#access-list 130 permit tcp any host eq 80 Router(config)#access-list 130 permit tcp Eq 21 Router(config)#access-list 130 permit icmp any Router(config)#access-list 130 permit tcp any eq 23 Router(config)#access-list 130 permit udp any host eq 53

Switch port ACL
You can only apply port ACLs to layer 2 interfaces on your switches because they are only supported on physical layer 2 interfaces. You can apply them as only inbound lists on your interfaces, and you can use only named lists as well. Extended IP access lists use both source and destination addresses as well as optional protocol information and port number. There are also MAC extended access lists that use source and destination MAC addresses and optional protocol type information. Switches scrutinize all inbound ACLs applied to a certain interface and decide to allow traffic through depending on whether the traffic is a good match to the ACL or not. ACLs can also be used to control traffic on VLANs. You just need to apply a port ACL to a trunk port. Switch#conf ter Switch(config)#mac access-list extended abc Switch(config-ext-mac)#deny any host 000d.29bd.4b85 Switch(config-ext-mac)#permit any any Switch(config-ext-mac)#do show access-list Switch(config-ext-mac)#int f0/6 Switch(config-if)#mac access-group abc in

Lock and Key (Dynamic ACLs)

These ACLs depends on either remote or local Telnet authentication in combination with extended ACLs. Before you can configure a dynamic ACL, you need to apply an extended ACL on your router to stop the flow of traffic through it.

Reflexive ACLs
These ACLs filter IP packets depending upon upper-layer session information, and they often permit outbound traffic to pass but place limitations on inbound traffic. You can not define reflexive ACLs with numbered or standard IP ACLs, or any other protocol ACLs. They can be used along with other standard or static extended ACLs, but they are only defined with extended named IP ACLs.

Time-Based ACLs
In this you can specify a certain time of day and week and then identity that particular period by giving it a name referenced by a task. The reference function will fall under whatever time constraints you have dictated. The time period is based upon the router‟s clock, but it is highly recommended that using it in conjunction with Network Time Protocol (NTP) synchronization. Router#conf ter Router(config)#time-range no-http Router(config-time-range)#periodic <Wednesday|weekdays|weekend> 06:00 to 12:00 Router(config-time-range)#exit Router(config)#time-range tcp-yes Router(config-time-range)#periodic weekend 06:00 to 12:00 Router(config-time-range)#exit Router(config)ip access-list extended time Router(config-ext-nacl)#deny tcp any any eq www time-range no-http Router(config-ext-nacl)#permit tcp any any time-range tcp-yes Router(config-ext-nacl)#interface f0/0 Router(config-if)#ip access-group time in Router(config-if)#do show time-range

Remarks are the comments or remarks regarding the entries you have made in both your IP Standard and Extended ACLs. Router#conf ter Router(config)#access-list 110 remark <remark words> permit rahul from admin only to sale Router(config)#access-list 110 permit ip host Router(config)#access-list 110 deny ip Router(config)#ip access-list extended no_telnet

Router(config-ext-nacl)#remark deny all of finance from telnetting to sale Router(config-ext-nacl)#deny tcp eq 23 Router(config-ext-nacl)#permit ip any any Router(config-ext-nacl)#do show run

Cisco Discovery Protocol
This protocol is by default enabled in Cisco devices. It will send periodic update after every one minute on all interfaces. The neighbors will receive this information and store in the CDP neighborship table. CDP is helpful in troubleshooting or to create documentation of CDP. We can obtain following information about neighbor automatically. (1) Hostname (2) Device type (3) Model/Platform (4) IOS version (5) Local connected interface (6) Remote device connected interface (7) Entry IP address etc. Display CDP status Router#sh cdp To display CDP enabled interfaces Router#sh cdp interface To display CDP neighbors Router#sh cdp neighbor Or Router#sh cdp neighbor detail To disable CDP from device Router#conf ter Router(config)#no cdp run To disable CDP on particular interface Router#conf ter Router(config)#int <type> <no.> Router(config-if)#no cdp enable Router(cobfig-if)#exit To change CDP timers Router#conf ter Router(config)#cdp timer <value> (by default 60 sec) Router(config)#cdp holdtime <value> (by default 180 sec) (Value in seconds)

Wide Area Network
The network that is design for long distance communication is called Wide Area Network. A WAN network uses WAN protocols, WAN interface card to communicate with remote network. WAN


Circuit Switching

Packet Switching

Cell Switching ATM

Leased line ISDN Frame Relay MLLN PSTN X.25 Radio Link For 2 locations Unlimited Maximum Factors to be considered while selecting a WAN technology (1) No. of locations (2) Hours of connectivity (3) Speed (4) Cost (Bandwidth + Distance) (5) Reliability


WAN Encapsulation WAN encapsulation is used to convert a packet into frame and transfer data to WAN links, Different type of encapsulation are designed for different WAN technologies. The general format of WAN encapsulation is: Flag Address Control Data FCS Flag

FH Common WAN Encapsulation Point-to-Point Point-to-Point, Circuit Switch Frame Relay Frame Relay X.25 ISDN ATM



High level data link control Point-to-Point Protocol Frame Relay Cisco Frame Relay IETF Link Access Procedure Based Link Access Procedure Based for D channel ATM Adaptation layer 5



Point-to-Point WAN technologies
These WAN technologies are used to connect two locations with each other. It is the 24hour high speed and reliable connectivity. We can setup this WAN technology in three steps: Step 1: - Connect the devices according to topology. Step 2: - Configure Modems. Step 3: - Configure Router.

Step 1 Point-to-Point WAN Topology (a) Campus n/w or Drop wire n/w Modem

V.35 RS 232 EIA/TIA 530

Line 2 wire TP Or 4 wire TP


DB-60 Smart Serial Serial Router eth RJ-45 * Distance depends on modems & mostly up to 10-15 kms. (b) Leased line via Service Provided G703 G704 Modem Line Local Loop Line Modem V.35 Modem Local Loop Mux Exchange Mux Modem Router



RS 232, EIA/TIA 530 SS, DB-60

(c) Managed Leased Line n/w (MLLN)




MLLN Modem

MLLN Modem



(d) Radio Link

V.35 RS 232 EIA 530

Radio Modem


Radio Modem

DB-60 Smart Serial Router Router

(e) Radio Link using IDU & ODU Radio Modem ODU UTP or Coaxial Router Radio Modem IDU Radio Modem IDU Router ODU – Out Door Unit IDU – In Door Unit Radio Modem ODU

Line 4 Wire 1 ------2 ------- Loop 1 3 4 ------- Loop2 5 ------ 6 7 8 2 Wire 1 2 3 4 ------- Signal 5 ------6 7 8

Step 2 Configurations of Modems

We have to configure various parameters in the modem. There are three different methods to configure these parameters according to Modem. Method1) Configuration of modem using Jumper setting/ Dip switches. 2) Configuration of modem using LCD menu. 3) Configuration of Modem using Console/ Terminal. Step 3 Configuration of Router To configure Router for a Leased line scenario or Point-to-Point n/w, we have to set following parameters: 1) IP addresses 2) IP routing 3) WAN encapsulation

In Point-to-Point WAN n/w any type of routing can be perform on routers.

WAN Encapsulation
Two routers interfaces in Point-to-Point WAN must required to have same WAN encapsulation. Two types of WAN encapsulation are supported in this type of network. (1) HDLC (2) PPP

HDLC PPP Same Manufacturer

PPP Different Manufacturer By default, Cisco routers will use Cisco HDLC encapsulation. We can change encapsulation by following command: Router#conf ter Router(config)#interface <type> <no> Router(config-if)#encapsulation ppp|hdlc HDLC High Level Data Link Control HDLC is the modified form of SDLC (Synchronous Data Link Control). SDLC was developed by IBM for router to main frame communication. HDLC is modified for router-to-router communication. Most of manufacturer has developed their proprietary HDLC protocol. So HDLC from one manufacturer is not compatible for other. HDLC encapsulation is designed for Point-to-Point router communication. In HDLC no addressing is required, but still all station address is used in encapsulation. HDLC provides only basic features and error checking for the frame. PPP – Point-to-Point Protocol PPP is an open standard WAN protocol that can be used in Point-to-Point and circuit switching networks. PPP provides various advantages as compared to HDLC. PPP has following special features: (1) Authentication (2) Multi Link (3) Compression (4) Call Back

PPP at OSI layer A P S T N Lan, Wan Protocols DL




Network D A NCP T ------------------A LCP L I -------------------N K HDLC Physical


Three Phases of PPP (1) Link Control Protocol (LCP) This protocol negotiates the basic feature of PPP. It exchanges the parameter and option to be used with link. LCP supported features are: Authentication, Compression, Multi link & Call back (2) Authentication Phase - optional In this phase authentication is performed with peers with the help of one of the following protocol. (i) Password Authentication Protocol (ii) Challenge Handshake Authentication Protocol (iii) Microsoft CHAP (iv) Shiva PAP (clear text) (3) Network Control Protocol Phase (NCP) In this phase parameters for routed protocol are established. In NCP, there is one module for each routered protocol. IPCP for TCP/IP IPXCP for IPX/SPX (internetwork packet exchange/sequenced packet exchange) CDPCP for CDP etc.

Configuring Authentication in PPP Example: Router 1 S0

Router 2 S1

Router 1 Router#config ter Router(config)#int serial 0 Router(config-if)# encapsulation ppp Router(config-if)# ppp authentication chap Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#hostname chd Router(config)#username ldh password net123 Router(config)#exit Router 2 Router#config ter Router(config)#int serial 1 Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#hostname ldh Router(config)#username chd password net123 Router(config)#exit Configuring Compression in PPP In PPP, one of the following three protocols can be used for compression (1) Stac (2) Predictor (3) Microsoft Point-to-Point Compression Router#config ter Router(config)#interface <type> <no> Router(config-if)#encapsulation ppp Router(config-if)#compress <Stac|MPPC|Predictor> Router(config-if)#exit To display Compression Router#show compress

PPP debug commands Router#debug ppp error Router#debug ppp authentication Router#debug ppp negotiation To display PPP status Router#show interface LCP Open LCP Closed LCP Request sent LCP Listen IPCP Open IPCP Closed CDPCP Open CDPCP Closed

Circuit Switching
In Circuit Switching, all users are connected to the Circuit Switching. Exchange cloud depending upon user request. A circuit is established between two locations and then data is transferred. A signaling protocol is used to establish the connectivity then data is transferred with the help of protocol used Point-to-Point WAN. Examples of Circuit Switching are: ISDN (Integrated Services Digital Network) PSTN (Public Switched Telephone Network)

Integrated Services Digital Network
ISDN is the high-end circuit switching technology, which is designed for voice, data and video. ISDN is the time division multiplexing technology, in which multiple channels are used to transfer rate.



BRI 2 B Channels 1 D Channel



30 B Channels 1 D Channel

23 B Channels 1 D Channel

B Channel (Bearer Channel) This channel carries data using data encapsulation. D Channel (Data Channel) This channel carries signal using signaling protocol. Time Division Multiplexing in ISDN BRI B1 S1 B2 S D Ch S B1 S B2 S --

T B1 B2 D Ch S ------------------------64 kbps 64 kbps 16 kbps 48 kbps

ISDN BRI Topology ISDN Cloud TE 1 S NT 2 S TE 2 NT 1 TA T NT 1 U 2 wire


Network Termination 1 Send/Receive ISDN BRI Signals Network Termination 2 Share ISDN between multiple users

NT 2

TE 1

Terminal Equipment 1 ISDN compatible device Terminal Equipment 2 Non-ISDN device Terminal Adapter Connects ISDN line with Non-ISDN device

TE 2


Topology 1: - Voice ISDN Phone 1 ISDN Phone 2 Topology 2: - Voice NT 1 4 ISDN Cloud


2 wire

Phone 1 TA NT 1 ISDN Cloud

Phone 1

Topology 3: - Voice + Data


USB Serial TA

NT 1

ISDN Cloud

Ph 1

Ph 2

Install TA in Pc, similar to External modem installation. Use “Dialup Networking” to connect Remote location.

Topology 3: - Data Router ISDN BRI S/T NT 1 ISDN Cloud

Router NT 1 ISDN BRI U

ISDN Cloud

Configuring ISDN BRI We will configure ISDN BRI for following two scenarios: (1) ISDN Branch office to Branch office connectivity. (2) ISDN Branch office to ISP Connectivity.

ISDN Branch office to Branch office

ISDN Cloud Switch type Basic-net3 ISDN Switch ISDN Switch Switch type Basic-ni


288288 R1 R2

Encapsulation - PPP Authentication - CHAP Hostname R1 - Chd Hostname R2 - Del Password – net123 Routing - Static

172.16.X.X Demand Dial Routing Steps: (1) Specify interesting Topic (2) Configure Route (3) Dial to Remote location (4) Negotiate Parameters (5) Transfer Data (6) Monitor interesting traffic (7) Disconnect the call R1 Router#config ter Router(config)#int eth0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#ip route BRI 0 Router(config)#dialer-list 5 protocol ip permit Or Router(config)#access-list 20 deny Router(config)#access-list 20 deny Router(config)#access-list 20 permit any Router(config)#dialer-list 8 protocol ip list 20 Router(config)#isdn switch-type basic-net3 Router(config)#hostname Chd Router(config)#username Del password net123 Router(config)#int bri 0 Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap Router(config-if)#ip address Router(config-if)#dialer map ip name Del 288288


Router(config-if)#dialer hold-queue 10 (no. of packets range 1 – 100) Router(config-if)#dialer-group 8 Router(config-if)#dialer idle-timeout 180 Router(config-if)#no sh (if no response from the dialer connection break) Router(config-if)#exit

R2 Router#config ter Router(config)#int eth0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#ip route BRI 0 Router(config)#dialer-list 5 protocol ip permit Or Router(config)#access-list 30 deny Router(config)#access-list 30 deny Router(config)#access-list 30 permit any Router(config)#dialer-list 8 protocol ip list 30 Router(config)#isdn switch-type basic-net3 Router(config)#hostname Del Router(config)#username Chd password net123 Router(config)#int bri 0 Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap Router(config-if)#ip address Router(config-if)#dialer map ip name Chd 306306 Router(config-if)#dialer hold-queue 10 Router(config-if)#dialer-group 8 Router(config-if)#dialer idle-timeout 180 Router(config-if)#no sh Router(config-if)#exit ISDN Branch office to ISP Internet

E1/T1 ISDN Cloud Basic-net3 RAS 383843 R


DNS Router ISP Parameter Ph no. Username Password ISDN Service Provider Switch Type Router#config ter Router(config)#int eth 0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route bri 0 Router(config)#dialer-list 7 protocol ip permit Router(config)#isdn switch-type basic-net3

Authentication Accounting Authorization

Router(config)#int bri 0 Router(config-if)#ip address negotiated Router(config-if)#encapsulation ppp Router(config-if)#ppp authentication chap pap call in Router(config-if)#ppp pap sent-username <ispuser> password <word> Router(config-if)#ppp chap hostname <ispuser> Router(config-if)#ppp chap password <word> Router(config-if)#dialer string 383843 Router(config-if)#dialer-group 7 Router(config-if)#dialer-idle timeout 180 Router(config-if)#dialer hold-queue 10 Router(config-if)#no sh Router(config-if)#exit

NAT for ISDN dialup ISP connectivity Router#conf ter Router(config)#int eth 0 Router(config-if)#ip nat inside Router(config-if)#int bri 0 Router(config-if)#ip nat outside Router(config-if)#exit Router(config)#access-list 50 permit any Router(config)#ip nat inside source list 50 interface bri 0 overload Testing and Troubleshooting of ISDN (i) To display present active call Router#sh isdn active (ii) To display history of calls Router#sh isdn history (iii) To display ISDN status Router#sh isdn status Layer1 = Active Layer2 Multiple frame established Layer3 1 Active layer call or 2 Active layer 3 call (iv) To place ISDN test call Router#isdn call interface <type> <no> <phone no>

(v) To disconnect a call Router#isdn disconnect interface bri 0 <no> all Debug Commands Interesting traffic or dialer Router#debug dialer events Router#debug dialer packets ISDN problem Router#debug isdn events Router#debug isdn 2921 Error code at Router#debug isdn 2931 PPP problem Router#debug ppp negotiation

Router#debug ppp authentication Router#debug ppp error Configuring ISDN multi-link An ISDN multiple channels can be combined to dial the same location and transport data for this purpose. We will use PPP multi-link and Cisco bandwidth on demand configuration. Router#conf ter Router(config)#int bri 0 Router(config-if)#ppp multilink Router(config-if)#dialer load-throshold <value> either (inbound or outbound) 1-255 Router(config-if)#exit

Packet Switching
Packet Switching is the wan technology in which all devices are connected to the packet switching exchange. The devices will request packet switching exchange to create a virtual connection then data is transferred over the virtual connection. It is possible to create more than one virtual connection. Simuntasouly and transfer data over them one by one. Example of Packet Switching Technology are: (1) X.25 (2) Frame Relay Frame Relay Frame Relay is the Packet switching technology in which virtual connections are established. The frame relay supports only permanent virtual connections. Frame used special addresses called DLCI to create common and virtual connections. Frame Relay Topology FR SW

4 wire Tp

FR Modem Line Local loop

V.35 232 530

FR Modem


V.35, RS232, EIA 530

DB-60, Smart Serial Router


Frame Relay Encapsulation
Frame Relay use special type of Encapsulation, Which is specifically designed for this technology. There are two encapsulations are available: (1) Frame Relay Cisco (2) Frame Relay IETF (Internet Engineering Task Force)

R Cisco FR IETF FR Cisco



R IETF FR Non Cisco



Frame Relay DLCI DLCI stands for Data Link Control Identifier. It is used for addressing purpose. In frame Relay Encapsulation, Virtual Circuits are established and data is transferred on the basis of DLCI. DLCI addresses are different from general addressing scheme. One DLCI address provided for each virtual circuit that we want to create. DLCI range 16 - 1017 Virtual Circuit In packet switching technology there are two types of virtual circuits: (1) Switched Virtual Circuit (SVC) (2) Permanent Virtual Circuit (PVC) Only PVC is supported in Frame Relay technology. Frame Relay Local Management Interface LMI are the keepalive signals, which are used to keep the virtual circuit up and running. LMI are exchange between frame relay switch and router. We have to set same LMI on router as specified by the service provider. There are three types of LMI that we can use (1) CISCO (2) Q933a (3) ANSI

Configuring Frame Relay Point to Point connectivity

S0 Cisco SW





300 for R2 encap: - Cisco FR M

400 for R1

M R1 R2

R1 Router#config ter Router(config)#int eth0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#int serial 0 Router(config-if)#encapsulation frame-relay Router(config-if)#frame-relay lmi-type cisco Router(config-if)#ip address Router(config-if)#frame-relay interface-dlci 300 Router(config-dlci)#exit Router(config-if)#frame-relay map ip 300 Router(config-if)#no sh Router(config-if)#exit R2 Router#config ter Router(config)#int eth0 Router(config-if)#ip address

Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#int serial 0 Router(config-if)#encapsulation frame-relay Router(config-if)#frame-relay lmi-type cisco Router(config-if)#ip address Router(config-if)#frame-relay interface-dlci 400 Router(config-dlci)#exit Router(config-if)#frame-relay map ip 400 Router(config-if)#no sh Router(config-if)#exit

Frame-relay Switch Router(config)#hostname FR-SW FR-SW(config)#frame-relay switching FR-SW(config)#int serial0 FR-SW(config-if)#encapsulation frame-relay FR-SW(config-if)#no ip address FR-SW(config-if)#frame-relay intf-type dce FR-SW(config-if)#frame-relay route 300 int serial 1 400 FR-SW(config-if)#clocka rate 64000 FR-SW(config-if)#no sh FR-SW(config-if)#exit FR-SW(config)#int serial1 FR-SW(config-if)#encapsulation frame-relay FR-SW(config-if)#no ip address FR-SW(config-if)#frame-relay intf-type dce FR-SW(config-if)#frame-relay route 400 int serial 0 300 FR-SW(config-if)#clocka rate 64000 FR-SW(config-if)#no sh FR-SW(config-if)#exit Configuring Frame Relay point to multipoint when all routers are same subnet


VC1 VC2 R2 400 for R1 M M

M 309 for R2 318 for R3

M 701 for R1

M M R1 R3 Encapsulation = Frame-Relay IETF

On physical interface, we can assign only one DLCI address. But in this case, we have to use two DLCI on single interface so we will create a frame relay sub interface (multipoint), which is able to create multiple virtual circuit. R1 Router#config ter Router(config)#int eth 0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#ip route Router(config)#int serial 0 Router(config-if)#encapsulation frame-relay ietf Router(config-if)#frame-relay lmi-type ansi Router(config-if)#no ip address Router(config-if)#no sh Router(config-if)#exit

Router(config)#interface serial 0.2 multipoint Router(config-if)#ip address Router(config-if)#frame-relay map ip 309 Router(config-if)#frame-relay map ip 318 Router(config-if)#no sh Router(config-if)#exit R2 Router#config ter Router(config)#interface Ethernet 0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#interface serial 0 Router(config-if)#ip address Router(config-if)#encapsulation frame-relay Router(config-if)#frame-relay interface-dlci 400 Router(config-dlci)#exit Router(config-if)#frame-relay lmi-type ansi Router(config-if)#frame-relay map ip 400 Router(config-if)#no sh Router(config-if)#exit R3 Router#config ter Router(config)#interface Ethernet 0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#interface serial 0 Router(config-if)#ip address Router(config-if)#encapsulation frame-relay Router(config-if)#frame-relay interface-dlci 701 Router(config-dlci)#exit Router(config-if)#frame-relay lmi-type ansi Router(config-if)#frame-relay map ip 701 Router(config-if)#no sh Router(config-if)#exit Frame-relay Switch

Router(config)#hostname FR-SW FR-SW(config)#frame-relay switching FR-SW(config)#int serial0 FR-SW(config-if)#encapsulation frame-relay FR-SW(config-if)#no ip address FR-SW(config-if)#frame-relay intf-type dce FR-SW(config-if)#frame-relay route 309 int serial 1 400 FR-SW(config-if)#frame-relay route 318 int serial 2 701 FR-SW(config-if)#clocka rate 64000 FR-SW(config-if)#no sh FR-SW(config-if)#exit FR-SW(config)#int serial1 FR-SW(config-if)#encapsulation frame-relay FR-SW(config-if)#no ip address FR-SW(config-if)#frame-relay intf-type dce FR-SW(config-if)#frame-relay route 400 int serial 0 309 FR-SW(config-if)#clocka rate 64000 FR-SW(config-if)#no sh FR-SW(config-if)#exit FR-SW(config)#int serial2 FR-SW(config-if)#encapsulation frame-relay FR-SW(config-if)#no ip address FR-SW(config-if)#frame-relay intf-type dce FR-SW(config-if)#frame-relay route 701 int serial 0 318 FR-SW(config-if)#clocka rate 64000 FR-SW(config-if)#no sh FR-SW(config-if)#exit

Frame Relay point to multipoint configuration when routers are in different subnets.


VC1 VC2 R1 400 for R1 M M

M 300 for R2 309 for R3

M 701 for R1

M M R1 Encapsulation = Frame-Relay IETF R1

R1 Router#config ter Router(config)#int eth0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip route Router(config)#ip route Router(config)#interface serial 0 Router(config-if)#encapsulation frame-relay ietf Router(config-if)#frame-relay lmi-type cisco Router(config-if)#no ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#interface serial 0.20 point-to-point Router(config-if)#ip address Router(config-if)#frame-relay interface-dlci 300 Router(config-if)#exit

Router(config-if)#frame-relay map ip 300 Router(config-if)#no sh Router(config-if)#exit Router(config)#interface serial 0.30 point-to-point Router(config-if)#ip address Router(config-if)#frame-relay interface-dlci 309 Router(config-if)#exit Router(config-if)#frame-relay map ip 309 Router(config-if)#no sh Router(config-if)#exit Frame Relay Show Command Router#sh interface <type> <no> It will be show additional (i) Encapsulation (ii) LMI send/receive Router#sh frame-relay pvc It will be show (i) Active/inactive pvc (ii) Data send/receive over each pvc (iii) Frame-relay congestion control information Router#sh frame-relay map Display the IP to DLCI mapping and pvc status Frame relay congestion control Frame relay uses three types of information in frame relay encapsulation for congestion control. (1) Backward explicit congestion notice. (2) Forward explicit congestion notice (3) Discard eligibility

Network Address Translation
NAT is the feature that can be enable in a Router, Firewall or a Pc. With the help of NAT, we are able to translate network layer addresses that are IP addresses of packets. With the help of Port Address Translation, we are also able to translate port no.s present in transport layer header.

Advantage of NAT
There are two reasons due to which we use NAT: (1) Conserve Live IP address

On Internet, there are limited no of IP addresses. If our Pc wants to communicate on Internet then it should have a Live IP address assigned by our ISP. So that IP address request will depend on no. of PCs that we want to connect on Internet. Due to this, there will be a lot of wastage in IP addresses. To reduce wastage, we can share live IP addresses between multiple PCs with the help of NAT. (2) NAT enhances the network security by hiding PC & devices behind NAT.

Working of NAT & PAT

Internet Switch NAT 1080 1085 1024

Port Translation 1100 1024

Types of NAT
Static NAT This NAT is used for servers in which one Live IP is directly mapped to one Local IP. This NAT will forward on the traffic for the Live IP to the Local PC in the n/w.

Static NAT = Router Live Internet


Port Base Static NAT This NAT is also used for servers. It provides port-based access to the servers with the help of NAT. -> -> Router Internet



Dynamic NAT using Pool Dynamic NAT is used for clients, which want to access Internet. The request from multiple client IPs are translated with the Live IP obtained from the Pool. It is also called Pool Based Dynamic NAT. Pool => – Local address => 172.16.X.X Except => Router


Web Server DNS Full access Pool allotted => – 15/28 Server Static => = Port Based Static NAT = = Client Dynamic NAT Pool => – Local address => 172.16.0.X


Except Configuring NAT Router#conf ter Router(config)#int serial 0 Router(config-if)#ip nat outside Router(config-if)#int eth 0 Router(config-if)#ip nat inside Router(config-if)#exit Router(config)#ip nat inside source static Router(config)#ip nat inside source static tcp 80 80 Router(config)#ip nat inside source static udp 53 53 Router(config)#access-list 30 deny Router(config)#access-list 30 deny Router(config)#access-list 30 deny Router(config)#access-list 30 permit any Router(config)#ip nat pool abc netmask Router(config)#ip nat inside source list 30 pool abc overload

NAT + PAT To display NAT translation Router#sh ip nat translations (after ping any address, it shows ping details) To clear IP NAT Translation Router#clear ip nat Translation *

Configuring DHCP
Router(config)#int eth0 Router(config-if)#ip address Router(config-if)#no sh Router(config-if)#exit Router(config)#ip dhcp pool abc Router(dhcp-config)#network Router(dhcp-config)#default-router Router(dhcp-config)#dns-server Router(dhcp-config)#domain-name

Router(dhcp-config)#lease 3 Router(dhcp-config)#exit Router(config)#ip dhcp excluded-address Router(config)#exit

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