Network layer notes

Network  layer

•       Logical Addressing-The network layer is responsible for the source-to-destination delivery of a packet, possibly across multiple networks.

•       The network layer adds a header that includes a logical address(IP address) of the sender and the receiver to the  packet coming from the upper layer.

•        Routing- When independent networks or links are connected together to create an internetwork, routers or switches routes the packets to their final destination.

IP Addresses

An IP address is a 32-bit address.

The IP addresses are unique.

RULE:

If a protocol uses N bits to define an address, the address space is 2^N because each bit can have two

different values (0 and 1) and N bits can have 2^N values.

The address space of IPv4 is

2³²
or
4,294,967,296.

NOTATIONS

•       Binary Notation

01110101   10010101   00011101   11101010

•       Dotted-decimal notation

•       Hexadecimal Notation

0111 0101   1001 0101   0001 1101   1110 1010

                       75               95             1D               EA

                                            0x75951DEA

•       Some rules regarding the different notations of IP  addresses:-

1)      There should not  be any leading zero.

2)      There should  not be more than four numbers in an IPv4 address.

3)      Each number should be less than or equal to 255.

4)      A mixture of any two notation in IP addressing is not allowed.