Why is tcp checksum required

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Featured on Meta. Now live: A fully responsive profile. Related 0. The TCP header usually varies from 20 Bytes with no bits of option fields being used to 60 Bytes with all bits of options field being used. It has fields like Source and Destination Port addresses, urgent pointer, Checksum, etc.

Now, the main ambiguity that arises that what is how can checksum be calculated on IP header as IP comes into the picture in the layer below the Transport Layer. Skip to content. Change Language. Thanks Ram. Labels: Labels: Other Routing.

All forum topics Previous Topic Next Topic. Giuseppe Larosa. Hall of Fame Master. Hello Ram, the OSI model with its layers is thought to have each level to perform its own checks: so L2 CRC is performed at layer2 IP checksum is only performed for the ipv4 header first 20 bytes not for the payload.

This makes a lot of difference. IPv4 header checksum is limited to header. Hope to help Giuseppe. In response to Giuseppe Larosa. Hello Giuseppe. Thanks Ramamoorthy. In response to ramamoorthy. Skip to main content. Start your free trial.