[Sip-implementors] question about branch field

[Roland]

the branch field in the via header has two parts. according to the rfc2543, the first part is for loop check:             The "branch" parameter MUST depend on the incoming request-URI to distinguish looped requests from re-quests             whose request-URI is changed and which then reach a server visited earlier. since request-URI is only information to check loop by branch, so the first branch part only encode request-URI ? the second part seems for seeking the corresponding request. so Which information should be encoded inside? a branch in some document such as 7a83e5750418bce23d5106b4c06cc632.1. Which part is for loop-check? which part is for matching a previous request? why the second part usually only has small information?   thanks, roland