Lower layers.


In order to communicate, hosts must speak the same protocol at each layer.

If you change the protocol at one layer on a host, you must change it on all other communicating hosts.

Some notes on Ethernet:


Details of TCP/IP:


IP Addresses

1100 0000 0000 1010 0001 0101 0001 1011

has the hexadecimal representation of

C0 0A 15 1B

and therefore would be written as


Special Addresses

Class      Leading Bits           Remaining Bits
D             1110                        Group Identification (28 bits)