Network Design and Analysis
Dr. Nawaporn Wisitpongphan
• We’ll follow CCDA Material, ―Designing for Cisco
• Here’s the class protocol:
– Students shall read the material before coming to
– Easy questions will be given out as a pop quiz during
• 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
• Hand-On Activity
• Class Project
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
• 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
• Assignment 10%
• Quiz 15%
• Class Project 15%
• Midterm 30%
• Final 30%
• OSI Model and its Functions
• LANs and WANs
• Network Devices
• Switching Types
• Spanning Tree Protocol
• Virtual LANs
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.
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.
Data Link Layer
defines the format of data that is to be transmitted across the physical
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.
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
The routing protocols determine the best path that should be used to
forward the routed data through the internetwork to its destination.
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
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.
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
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).
■ 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
■ 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 .
■ 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-
■ 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
■ 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.
• A domain is a specific part of a network.
– Broadcast Domain: includes all devices that receive each
– 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.
• 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.
• Read src/dst MAC addresses and send data to a specific
• All devices connected to one switch port are in the same
• By default, all devices connected to a switch are in the same
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.
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
■ HTTP: Transfers information to and from a
World Wide Web server through web browser TCP UDP
■ Telnet: Emulates a terminal to connect to Oriented
■ Domain Name System (DNS): Translates Best- Effort
network device names into network addresses
■ Simple Network Management Protocol Control
(SNMP): Used for network management,
including setting threshold values and reporting Unreliable
■ Dynamic Host Configuration Protocol Stream of Byte
(DHCP): Assigns dynamic IP addressing
information to devices as they require it. End-to-End
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
Window-Based Flow Control
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.
Routing and Routers
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
Routers learn routes
from other routers by using a routing
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)
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.
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
Can you give an example of
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.
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
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?
-Receive duplicate broadcast copies
-Unstable MAC Address table
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
“[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.”
A Router, Using Either Multiple Physical Interfaces or a Trunk, Is Required for
Communication Among VLANs
Homework For Next Week
Read Chapter 2 !!!