- 32 bits in length writen in 4 fields of 8 bit each separated by a dot “.”
All IP addresses in the same group must not be separated from each other by a router.
IP addresses separated from each other by a router must be in different groups.
x.x.x.x = len(x) * 4 = 32 Bits
X is called octet. Each octet consists of 8 bits.
Classful IP addressing
Used when IP addressing was brand new, it was broken down into classes. Nowadays IP addresses are not broken down classfully, but classlessly ().
|Class||Value of 1st octet||Subnet mask||Example|
- A magazine subscription The hosts have to subscribe to the “master”
- Reserved for experimental purposes
Structure of the IP
A subnet mask separates a host address from the network address.
Convert IP addr to binary
Class C address
IP = 184.108.40.206 –> First octet is
200 / Network mask: 255.255.255.0
1*128 + 1*64 + 0*32 + 0*16 + 1*8 + 0*4 + 0*2 + 0*1 = 200
Class B address
IP = 220.127.116.11 / Network address: 255.255.0.0
Network adress: 18.104.22.168/16
Broadcast address: 22.214.171.124
Last valid IP address: 126.96.36.199
Number of available address: 2^n - 2, where n = 16 because 16 bits of host address
188.8.131.52/24 –> Network address
184.108.40.206 –> Broadcast address
Number of available IP address
For previous example it is: 220.127.116.11 - 18.104.22.168
Formula: 2^n - 2, where n = host bits (-2 because you cannot use the first and the last address)
- Layer 3 function The process of going from one broadcast domain to another broadcast domain (both Layer 3 domains)
When H1 sends an ARP broadcast message, r1 will act as a proxy Arp responding with its own MAC address (on f0/0).