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					Network Design and Analysis
 Dr. Nawaporn Wisitpongphan
                  Introduction
• We’ll follow CCDA Material, ―Designing for Cisco
  Internetworking Solution‖
• Here’s the class protocol:
  – Students shall read the material before coming to
    class
  – Easy questions will be given out as a pop quiz during
    class…
     • If you read, you should be able to do it!!
  – Instructor present the class material
     • I’m Expecting an Interactive Class Here!! 
  – There will be some
     • Assignments
     • Hand-On Activity
     • Class Project
                                                            2
What will be covered exactly?
•   Chapter 1 Network Fundamentals Review
•   Chapter 2 Applying a Methodology to Network Design
•   Chapter 3 Structuring and Modularizing the Network
•   Chapter 4 Designing Basic Campus and Data Center
    Networks
•   Chapter 5 Designing Remote Connectivity
•   Chapter 6 Designing IP Addressing in the Network
•   Chapter 7 Selecting Routing Protocols for the Network
•   Chapter 8 Voice Network Design Considerations
•   Chapter 9 Wireless Network Design Considerations
•   Chapter 10 Evaluating Security Solutions for the Network
                                                               3
Here’s your
 BIBLE!!




              4
Here’s your
 BIBLE!!




              5
           Grading Criteria

•   Assignment 10%
•   Quiz 15%
•   Class Project 15%
•   Midterm 30%
•   Final 30%



                              6
                  Chapter 1

•   OSI Model and its Functions
•   LANs and WANs
•   Network Devices
•   TCP/IP
•   Routing
•   Addressing
•   Switching Types
•   Spanning Tree Protocol
•   Virtual LANs
                                  7
OSI Model
     KEY POINT
     The OSI model does not specify
     how these things are to be done,
     just what needs to be done.
     Different protocols can implement
     these functions differently.




                                         8
              Physical Layer

The OSI physical layer defines specifications such as the electrical
and mechanical conditions necessary for activating, maintaining,
and deactivating the physical link between devices.

Specifications include voltage levels, maximum cable lengths,
connector types, and maximum data rates.

The physical layer is concerned with the binary transmission of
data. This binary data is represented as bits (which is short for
binary digits). A bit has a single binary value, either 0 or 1.




                                                                    9
                  Data Link Layer

defines the format of data that is to be transmitted across the physical
network.

It indicates how the physical medium is accessed, including physical
addressing, error handling, and flow control.

The data link layer sends frames of data; different media have different
types of frames.




                                                                           10
                     Network Layer


The network layer is responsible for routing, which allows data to be
properly forwarded across a logical internetwork (consisting of
multiple physical networks).

Logical network addresses (as opposed to physical MAC addresses)
are specified at Layer 3. Layer 3 protocols include routed and routing
protocols.

The routing protocols determine the best path that should be used to
forward the routed data through the internetwork to its destination.




                                                                         11
              Transport Layer

Layer 4, the transport layer, is concerned with end-to-end connections
between the source and the destination. The transport layer provides
network services to the upper layers.


Connection-oriented reliable transport establishes a logical connection
and uses sequence numbers to ensure that all data is received at the
destination.



Connectionless best-effort transport just sends the data and relies on
upper-layer error detection mechanisms to report and correct problems.
Reliable transport has more overhead than best-effort transport.


                                                                          12
                Layer 5 – Layer 7

The session layer, Layer 5, is responsible for establishing, maintaining,
and terminating communication sessions between applications running
on different hosts.

The presentation layer, Layer 6, specifies the format, data structure,
coding, compression, and other ways of representing the data to ensure
that information sent from one host’s application layer can be read by
the destination host.

The application layer, Layer 7, is the closest to the end user; it interacts
directly with software applications that need to communicate over the
network.



                                                                               13
Communication among
    OSI Layers




                      14
                            LANs and WANs
                                      Which one is faster?




WANs interconnect devices that are usually connected to LANs and are located over a relatively broad geographic area
(hence the term wide-area network). Compared to a LAN, a typical WAN is slower, requires a connection request when you
want to send data, and usually belongs to another organization (called a service provider).
                                                                                                                  15
                    LANs: Examples
■ Ethernet and IEEE 802.3, running at 10 megabits per second (Mbps), use a
carrier sense multiple access collision detect (CSMA/CD) technology. Fast Ethernet
(at 100 Mbps), covered by the IEEE 802.3u specification, also uses the CSMA/CD
technology.

■ Gigabit Ethernet (running at 1 gigabit per second [Gbps]) is covered by the IEEE
802.3z and 802.3ab specifications and uses the CSMA/CD technology.

■ Wireless LAN (WLAN) standards, defined by the IEEE 802.11 specifications, are
capable of speeds up to 54 Mbps under the 802.11g specification. WLANs use a
carrier sense multiple access collision avoidance (CSMA/CA) mechanism .




                                                                               16
                   WANs: Examples

■ Packet-switched network: A network that shares the service provider’s facilities.
The service provider creates permanent virtual circuits and switched virtual circuits that
deliver data between subscribers’ sites. Frame Relay is an example of a packet-
switched network.

■ Leased line: A point-to-point connection reserved for transmission. Common data link
layer protocols used in this case are PPP and High-Level Data Link Control (HDLC).

■ Circuit-switched network: A physical path reserved for the duration of the connection
between two points. ISDN Basic Rate Interface (BRI) is an example of this type of
network.

■ DSL: Uses unused bandwidth on traditional copper telephone lines to deliver traffic at
higher speeds than traditional modems allow.

■ Cable: Uses unused bandwidth on cable television networks to deliver data at higher
speeds than traditional modems allow.

                                                                                             17
         Network Terminology
• A domain is a specific part of a network.
   – Broadcast Domain: includes all devices that receive each
     others’ broadcasts
   – Collision Domain: all devices that share the same bandwidth.
• Bandwidth is the amount of data that can be carried
  across a network in a given time period.
• Transmission Technique
   – Unicast data is data meant for a specific device.
   – Broadcast data is data meant for all devices; a special
     broadcast address indicates this.
   – Multicast data is data destined for a specific group of devices;
     need a special address.
                                                                        18
          DevicesCables?
• Hub :
    • repeats all the data received on any port to all the other
      ports; thus, aka a repeaters.
    • All devices connected to a hub are in one collision domain
      and one broadcast domain.

• Switch:
    • Read src/dst MAC addresses and send data to a specific
      interface.
    • All devices connected to one switch port are in the same
      collision domain.
    • By default, all devices connected to a switch are in the same
      broadcast domain.
                                                                   19
               Switch vs. Bridge

■ Switches are significantly faster because they switch in hardware, whereas
bridges switch in software.

■ Switches can interconnect LANs of unlike bandwidth. A 10-Mbps Ethernet
LAN and a 100-Mbps Ethernet LAN, for example, can be connected using a
switch. In contrast, all the ports on a bridge support one type of media.

■ Switches typically have more ports than bridges.

■ Modern switches have additional features not found on bridges; these
features are described
in later chapters.




                                                                               20
   Routers

         What’s the difference
      between router and switch?



It is a Layer 3 device that has much more
intelligence than a hub or switch.

         All devices connected to one router port are
         in the same broadcast/collision domain, but
         devices connected to different ports are in
         different broadcast/collision domains.

     Deliver packets to any address on the
     networks, not just the devices on other
     ports.
                                                   21
                       Transport Layer
     Important Applications
■ HTTP: Transfers information to and from a
World Wide Web server through web browser          TCP                    UDP
software.
                                                         Connection
■ Telnet: Emulates a terminal to connect to               Oriented
devices.
■ Domain Name System (DNS): Translates                    Best- Effort
network device names into network addresses
and                                                      Connectionless
vice versa.
                                                          Congestion
■ Simple Network Management Protocol                       Control
(SNMP): Used for network management,
including setting threshold values and reporting           Unreliable
network errors.
■ Dynamic Host Configuration Protocol                    Stream of Byte
                                                             Service
(DHCP): Assigns dynamic IP addressing
information to devices as they require it.                End-to-End
                                                           Reliable             22
                    TCP vs. UDP




      TCP and UDP use protocol port numbers to distinguish among
      multiple applications that are running on a single device.


Well-Known Port : 1-1023                          Dynamic Port : 49151-65535
                   Registered Port : 1024-49151                          23
Port Numbers




               24
Three-Way Handshake




                      25
Window-Based Flow Control




                            26
Closing Connection




                     27
     Network Layer Protocols

IP: Provides connectionless, best-effort delivery of
datagrams through the network.

                  Internet Control Message Protocol (ICMP): Sends messages
                  and error reports through the network.




                                                                     28
Routing and Routers




                      29
Routing Tables

        Routes configured by network
        administrators are known as static
        routes because they are hard-coded in
        the router and remain there—static—
        until the administrator removes them.

        Routes to which a router is physically
        connected are known as directly
        connected routes.

        Routers learn routes
        from other routers by using a routing
        protocol.

                                          30
Example of Routing Protocols


 ■ Routing Information Protocol (RIP), versions 1 and 2 (RIPv1 and RIPv2)

 ■ Enhanced Interior Gateway Routing Protocol (EIGRP)

 ■ Open Shortest Path First (OSPF)

 ■ Integrated Intermediate System-to-Intermediate System (IS-IS)

 ■ Border Gateway Protocol (BGP) Version 4 (BGP-4)




                                                                            31
                          Addressing

Physical Address: 48-bit unique address, a.k.a. MAC Address

                Logical Address: 32-bit, a.k.a. IP Address




127.0.0.0 (any address starting with decimal 127) is reserved for loopback
functionality. Therefore, the first octet of Class A addresses ranges from 1 to 126.

                                                                                       32
                   Private vs.
               Public IP Addresses
Private addresses are reserved addresses to be used
only internally within a company’s network, not on the Internet.

        ■ 10.0.0.0 to 10.255.255.255
        ■ 172.16.0.0 to 172.31.255.255
        ■ 192.168.0.0 to 192.168.255.255


**All the IP addresses used in this book are private addresses, to avoid publishing anyone’s
registered address.

                                                 Can you give an example of
                                                    Private addresses?




                                                                                               33
                        Subnet




2s = the number of subnets created, where s is the number of
subnet bits (the number of bits borrowed from the host field).


2h – 2 = the number of host addresses available on each
subnet, where h is the number of host bits.




                                                                 34
Layer 2 Switch
     A switch uses the frame’s destination MAC
     address to determine the port to which it
     sends the frame.

     A switch uses the frame’s source MAC
     address to populate its MAC address table;
     the switch eavesdrops on the conversation
     between devices to learn which devices can
     be reached on which ports.


                         Layer 3 Switch?

                A Layer 3 switch performs all the same
                functions as a router; the differences are in
                the physical implementation of the device.

                Layer 3 switch == Router
                                                        35
         Spanning Tree Protocol
                                      STP is a Layer 2 protocol that prevents
                                      logical loops in switched networks that
                                      have redundant links.




                                           What happen if A
 Redundancy can cause problem
                                        broadcast ARP Request
                                              to find B?

-Broadcast Storm
-Receive duplicate broadcast copies
-Unstable MAC Address table

                                                                           36
     Spanning Tree Chooses the
           Port to Block




 Within an STP network, one switch is elected as the root bridge—it is at
 the root of the spanning tree. All other switches calculate their best path to
 the root bridge. Their alternative paths are put in the blocking state.

1.   Switch with lowest ID or MAC address is elected the root bridge
2.   All ports on the root bridge are called ―designated ports” ; they are all in ―forwarding state‖
3.   For other switches, one port with the fastest path to the root is the root port.
4.   If the cost are equals, it use the port with lower ID as the root port.                 37
STP States: Port Status




                          38
                   Virtual LANs

“[A] group of devices on one or more LANs that are configured (using
management software) so that they can communicate as if they were
attached to the same wire, when in fact they are located on a number of
different LAN segments. Because VLANs are based on logical instead of
physical connections, they are extremely flexible.”




                                                                          39
           Inter-VLAN Routing

A Router, Using Either Multiple Physical Interfaces or a Trunk, Is Required for
Communication Among VLANs




                                                                            40
Homework For Next Week


     Read Chapter 2 !!!




                         41

				
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