TCP/ UDP

Question

At transport layer "pseodoheader" is attached with each outgoing data from transport layer(along with data from upper layer and its own header).Psedoheader is a part or snapshot of header from network layer.. My question is being upper layer of network layer how transport layer generates the pseodoheader,, which is generated by network layer in as next step...

Answer 1

Pseudo-header is not same as actual IP header. It just mimics it giving correct entries for source and destination addresses. 

http://en.wikipedia.org/wiki/Transmission_Control_Protocol

Answer 2

Maybe this can also help

http://www.tcpipguide.com/free/t_TCPChecksumCalculationandtheTCPPseudoHeader-2.htm