On Mon, 02 Dec 2002 10:18:22 +0530, Ramana Divvi <ramanad@future.futsoft.com> said: > IHL ------> IHL is the Total IPv4 header length, maximum is 15 > ( 15x4 = 60 bytes) ----refer RFC 791 > DataOffset ------> DataOffset is total TCP header size ( in simple words) > , maximum is 15 ( 15x4 = 60 bytes) ----refer RFC 793 > From above two, combined TCP/IP header maximum length is 120 bytes. Correct. > But in RFC 1144 (page 13) , it was defined as 128 bytes. Is it correct? If > so please clarify the same. No. You need a 128 octet buffer *for the compressed header*. The hint is "since the output packet can be larger than the input packet". Contemplate the algorithm, and see if you can see what states will cause the 120 byte header to require 128 bytes after "compression". -- Valdis Kletnieks Computer Systems Senior Engineer Virginia Tech
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