Internetworking

– What is internetworking? Connect multiple networks of one or more organizations

into a large, uniform communication system. The resulting system is called an internetwork or

internet.

– What is Internet? The Internet is the specific global internetwork that grew

out of ARPA-NET for communication of between computer located anywhere in the world

Protocols

Each intermediate network must agree to handle transit in exchange for the right to send traffic throughout the internet.

Internetworking protocols– All computers and routers in an internet must

agree on a common set of internetworking protocols.

What is a protocol? revisited

A set of syntactic and semantic rules for communication. details of message formats How a computer should respond when a message arrives. How a computer handles errors or. Independent of lower layers or hardware.

TCP/IP protocol

– TCP/IP is the most widely used internetworking protocol suite.

TCP: Transmission Control Protocol.IP: Internet Protocol.

– TCP/IP is now the defacto standard for internetworking protocols.

TCP/IP suite

Here are some of the key features provided by TCP/IP suite:

Packet switching Logical addressing Dynamic rooting Name resolution

Packet switching

The data is divided in small chunks “packets”

– The packets are transmitted independently – Possibly by different routes– And reassembled at the other end.– This allows a faster transmission

Logical addressing

Every computer has physical address – Ethernet address 48 bits (MAC address)

90:AF:F4:CA:BA:03 Burned into the chip at the factory Physical addresses are of different formats With no hierarchical scheme

Uniform format: IP addresses 32 bits identifying the network and the host. Two systems can not connect to the Internet with the same

address at the same time. Translation of IP to Ethernet address and vice versa.

Dynamic rooting

Different routes can be taken from source to destination

Router can choose a path for the data depending on present conditions

Path taken

Name resolution

TCP/IP provides a mapping of domain name and numeric addresses – www.doc.gold.ac.uk = 158.223.1.108