– 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
– 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
Each intermediate network must agree to
handle transit in exchange for the right to
send traffic throughout the internet.
– All computers and routers in an internet must
agree on a common set of internetworking
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 is the most widely used internetworking
TCP: Transmission Control Protocol.
IP: Internet Protocol.
– TCP/IP is now the defacto standard for
Here are some of the key features provided
by TCP/IP suite:
The data is divided in small chunks
– The packets are transmitted independently
– Possibly by different routes
– And reassembled at the other end.
– This allows a faster transmission
Every computer has physical address
– Ethernet address 48 bits (MAC address)
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.
Different routes can be taken from source to
Router can choose a path for the data
depending on present conditions
TCP/IP provides a mapping of domain name
and numeric addresses
– www.doc.gold.ac.uk = 220.127.116.11