EE 281 Lecture Notes - Lecture 2: Selective Repeat Arq, Sliding Window Protocol, Sequence
Document Summary
To validate the checksum, the receiver performs the same arithmetic, generating a checksum for the segment and pseudo ip header. Since the segment checksum is included in the header for this computation, the result for an error-free packet will be all ones (0xffff). This computation reliably detects single bit errors in the segment. Segments from multiple sockets (sources) that are directed to the same host address and port number are received by the socket on that host that is associated with that port number. With tcp, a connected socket is associated with four values: Recall that with tcp sockets, a server first creates a socket whose sole purpose is listening for and accepting incoming connections. It does so with the listen system call. This socket is said to be in the listen state. It will never be used for data transfer. Its only purpose is to accept incoming connections.
