IP Addressing

IP Addressing:

Classes: (n is the network address portion, and h is the host address portion)	Reserved Addresses:
Class A: n.h.h.h, n ∈[0,127] (starts with 0) private: 10/8 Class B: n.n.h.h, n ∈[128.0,191.255] (starts with 10) private: 172.16/12 Class C: n.n.n.h, ∈[192.0.0,223.255.255] (starts with 110) private: 192.168/16 Class D: multicast Class E: research	Network address of 0s : this network or segment Network address of 1s : all networks Host address of 0s : this host Host address of 1s : all hosts Address of 1s : all nodes on current network - flooded broadcast Address of 0s : used by Cisco to designate the default route Address 127.0.0.1 : this node used for loopback tests.

IP Subnetting:

Information	Formula	Mask	number	Mask	number
Subnet address	yi=(256-number)*i	10000000	128	11111000	248
First host	yi+1	11000000	192	11111100	252
Last host	yi+1-2	11100000	224	11111110	254
Subnet broadcast address	yi+1-1	11110000	240	11111111	255

i∈ [1,n_s]

Number of subnets: n_s=2^(hostbits-x) – 2 , – hostbits is the number of bits reserved for the host in that class (8 for class C, …)

Number of hosts: n_h=2^x –2

where x is the number of unmasked bits

It is essential to know how to manipulate subnets to create a given number of hosts or subnets. It is also essential to be able to calculate the broadcast address of a given host or network and subnet mask.