Networking Concepts : IP

There are 7 layers in OSI Model:

1. Application layer
2. Presentation layer
3. Session layer
4. Transport layer
5. Network layer
6. Data link layer
7. Physical layer

Detailed explanation about each layer is already available online. I will not go into the discussion about the different layers of OSI model.

Easy way to remember the sequence of OSI Model is:

“Please Do Not Tell Sales People Anything”

IP Addressing is done in Network layer of OSI Model.

2 types of ip addressing:

1. IP V4
2. IP V6

IP V4:

It’s a 32 bit addressing.

Binary format, for eg: A.B.C.D will have 8 bit octet.

1 byte = 8 bit

So, 4 byte IP = 32 bit IP.

Maximum IP possible 255.255.255.255

IP V6:

It’s 128 bit addressing.

Hexadecimal format.

IP V4 Classification:

Class A:

X1.X2.X3.X4

Remember, Default Subnet Mask has only 2 parts: a) netword id b) host id.

X1 is Network ID. It’s fixed (Constant).

X2, X3, X4 are host ids and are variable host ids.

Class A IP range from 0 to 127. 0 is invalid,127 is loopback and 255 is for Broadcasting.

Range: 1.0.0.0 to 127.255.255.255

Subnet Mask: 255.0.0.0

Millions of ip’s are possible.

Class B:

X1.X2.X3.X4

X1, X2 is Network ID and constant.

X3, X4 is Host ID and variable.

Class B ip range from 128 to 191.

Range: 128.0.0.0 to 191.255.255.255

Subnet Mask: 255.255.0.0

1000’s of ips are possible.

Class C:

X1.X2.X3.X4

X1, X2, X3 is Network ID and constant.

X4 is Host ID and variable.

Class C ip range from 192 to 223.

Range: 192.0.0.0 to 223.255.255.255

Subnet Mask: 255.255.255.0

Only 254 ips are possible.

Class D:

X1.X2.X3.X4

X1, X2, X3, and X4 is Network ID and constant.

Class D ip range from 224 to 239.

Range: 224.0.0.0 to 239.255.255.255

Subnet Mask: 255.255.255.255

Class E:

Range from 240 to 255

Ip range is 240.0.0.0 to 255.255.255.255

Private IP Ranges:

10.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255

192.168.0.0 to 192.168.255.255