IPv4 subnetting

What do you know about IPv4?

     Having a 32 bit address
     Format (ddd.ddd.ddd.ddd)
     Divided into classes A, B, C, D, E
     IP Reserved

     # 10.0.0.0 - 10,255,255,255 - reserved for local intranet networks
     # 127.0.0.0 - 127 255 255 255 - reserved for local loop on each computer
     # 172.16.0.0 - 172.31.255.255 - reserved for local intranet networks
     # 192.168.0.0 - 192 168 255 255 - reserved for local intranet networks
     # 224.0.0.0 - 239 255 255 255 - used for multicast routing

An easy way to do subnetting are:

Subnetting is used to subdivide the IP group into smaller groups so as to facilitate the management and Setting routing.


example

ip subnet zero=default

class C

IP: 192.168.1.111 SUBNET: 255.255.255.128 (/25)

then:

255 255 255 128 converted in binary 11111111.11111111.11111111.10000000(/25)

1. ip range normal for this class there are 256 ie 0-255 so (max range - the 4th octet of the subnet) = 256-128 = 128 is 192.168.1.0 - 192.168.1.127

2. 2 rank in the last octet binary number. 2 rank 7 = 128



So obtained is

1. Range = IP subnet 1: 192.168.1.0 - 192.168.1.127 subnet 2: 192.168.1.128 - 192.168.1.255

2. Number of subnets = 2 rank number 1 in the binary number 2 rank last octet = 1: 2

2. Host IP = Range - 2 (ip network and broadcast): 126

3. Network = subnet 1: 192.168.1.0 subnet 2:192.168.1.128

4. Broadcast = subnet 1: 192.168.1.127 subnet 2: 192.168.1.255

5. IP 192.168.1.111 is on subnet 1


class B

There is a network address 172.16.0.0/18

172.16.0.0/28 found on the class B subnet mask / 18 means 11111111.11111111.11000000.00000000 (255.255.192.0).

calculation

Number of Subnet = 2 to the power x, where x is the number of binary number 1 on the last 2 octets. So the number of subnet mask is 2 to the power 2 = 4 subnets
 
The number of hosts per subnet = 2 to the power y-2, where y is the inverse of x is the large number of binary 0 in the last octet of the subnet mask 2. So the hosts 214-2 = 16.382
 
Block Subnet = 256-192 = 64, the next subnet is 64 + 64 = 128, and 128 +64 = 192. So the full subnet is 0, 64, 128, 192.

Subnet	172.16.0.0	172.16.64.0	172.16.128.0	172.16.192.0
Host Pertama	172.16.0.1	172.16.64.1	172.16.128.1	172.16.192.1
Host Terakhir	172.16.63.254	172.16.127.254	172.16.191.254	172.16.255.254
Broadcast	172.16.63.255	172.16.127.255	172.16.191.255	172.16..255.255

Posted in: CCNA