1. 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

2. 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.

3. 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.

4. 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.

5. TCP/IP suite Here are some of the key features provided by TCP/IP suite: Packet switching Logical addressing Dynamic rooting Name resolution

6. 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

7. 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.

8. 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

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