Lecture 7Internetworking

LAN Design Issues

Media; Topology; Protocol;

Addressing; Naming;

Example networking application.

Recap

Network Topology (cont)

Point to Point Star

Partial Mesh

Tree

Bus

Ring

Fully Connected

IP addressingIP Address192.168.15.2 (decimal)

11000000 10101000 00001111 00000010 (binary)

Subnet Mask:255.255.255.0 (decimal)

11111111 11111111 11111111 00000000 (binary)

IP Address192.168.15.2 (decimal)

11000000 10101000 00001111 00000010 (binary)

Subnet Mask:255.255.255.0 (decimal)

11111111 11111111 11111111 00000000 (binary)

Network part Host part

IP addressing (network/ broadcast)

.1

.254

192.168.15.0/24

For our example:

192.168.15.255 -> broadcast address;

Packet sent to broadcast address

.1

.254

A packet sent to broadcast address will be received by all nodes.

Range: 192.168.15.0 to 192.168.15.255;

Two addresses are reserved in every network1) host bits all zeros (for representing the network)

2) host bits all ones (for the broadcast address)

Example application

We assumed that a student (in the niit.edu.pk LAN) wanted to access NUST-SEECS website hosted at www.niit.edu.pk

WWWP

C

In the last lecture, we assumed a greatly simplified

model of the LAN of NUST-SEECS

Network’s domain name: niit.edu.pk

DNS Client/Server Exchange

WWW

DNS

Request

Tell me the IP address of www.niit.edu.pk?

WWW

DNSReply

The IP address of www.niit.edu.pk is 202.125.157.196

DNS Client/Server Exchange

The IP address of www.niit.edu.pk is 202.125.157.196

ARP Client/Server Exchange

WWW

DNS

Request

Any one knows the MAC (physical) address of 202.125.157.196 ?

Request

WWW

DNS

Reply

The MAC address of 202.125.157.196 is 12:34:aa:bb:cc:dd

ARP Client/Server Exchange

The MAC address of 202.125.157.196 is 12:34:aa:bb:cc:dd

Layered Communications

GET / HTML/1.1

Source MAC address | Destination MAC address 23:34:aa:bb:cc:dd | 12:34:aa:bb:cc:dd

FCSPayload

Payload

Source Port | Destination Port> 1024 | 80

Payload

Payload

Source IP | Destination IP 202.125.157.150 | 202.125.157.196

Payload

Application data

TCP Segment

MAC Frame

IP Packet

HTTP High-level Exchange

WWW

DNS

Send me the index.html page for the host www.niit.edu.pk

using HTTP version 1.1

Request

Send me the index.html page for the host www.niit.edu.pk

using HTTP version 1.1

WWW

DNS

Reply

The index.html page in the wwwroot directory configured for the www.niit.edu.pk webserver

is sent back to the browser for display

HTTP Client/Server Exchange

Quiz # 3

Internetworking

Today’s

lecture

Encapsulation/ layered communication;

Hierarchical addressing;

Interconnecting multiple networks;

Layered Communication

GET / HTML/1.1

Source MAC address | Destination MAC address 23:34:aa:bb:cc:dd | 12:34:aa:bb:cc:dd

FCSPayload

Payload

Source Port | Destination Port> 1024 | 80

Payload

Payload

Source IP | Destination IP 202.125.157.150 | 202.125.157.196

Payload

Application layer

Transport layer

Link layer

Internet layer

TCP/IP model

Application

Transport

Network

Data Link

Destination Host (Same LAN)

Bits

Bridges/ Switches

Repeater/ Hub

Source Host

Application

Transport

Network

Data Link

Bits

Networking devices (same LAN)

Device used in a single LAN: hub, bridge, switch

Application

Transport

Network

Data Link

Destination Host (Different network)

Bits

Routers/ Gateway

Source Host

Application

Transport

Network

Data Link

Bits

Internetworking devices (different LAN)

Routing example

Routing example

Course to be tested

Every thing we have studied in the classroom.

Topics covered in the assignment will not be

tested in this exam.

Details of material discussed in class (that is in

your textbook) may be tested.

Material from your textbook that was not covered

in the class at all will not be tested

Mid sessional format

3 Sections

a) Multiple choice questions

(30 marks)

b) Fill in the blanks

(30 marks)

c) Questions requiring short answers

(40 marks)

Types of questions:

d) Requiring lower-order skills

(memorization

and comprehension)

e) Requiring higher-order skills

(analyzing and

applying)

Lecture’s

Summary

a) We studied the

TCP/ IP layering model

b) We discussed basic networking device types:

1) hubs/ repeaters

; 2) bridges/ switches

;

3) routers.

c) We studied that

routers are necessary for

internetworking.

d) We discussed details of the

mid-semester exam.

???Questions/

Confusions?

Credits/ Acknowledgement can be found

at the course website:

http://tinyurl.com/5hb8pp