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The pseudo-header is not an IP header rather it is a part of the IP header. To overcome all these errors and increase error checking capability we use Pseudo IP header. The error checking capability of TCP/UDP in Transport Layer takes help from the network layer for proper error detection.īut the important concept to note here is that we actually don’t use the IP header rather we use a part of the IP header. Then how can we estimate the size of the IP header from the Transport because the guess/estimation would be definitely wrong and thus there would be no point in calculating the checksum on a field which is wrong at the beginning itself? In simple terms, it means that we are in Transport Layer and the IP data packet is created in Network Layer. 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. The CheckSum of the TCP is calculated by taking into account the TCP Header, TCP body and Pseudo IP header.
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In this article, we are only concerned about the CheckSum field of the TCP. It has fields like Source and Destination Port addresses, urgent pointer, Checksum, etc. 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). Difference between Synchronous and Asynchronous Transmission.nslookup command in Linux with Examples.Implementation of Diffie-Hellman Algorithm.
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