[Sip-implementors] VIA HEADER -Sent-By

[innovation.interops]

Hello all,

RFC 3261 says Before a request is sent, the client transport MUST insert a value of the "sent-by" field with FQDN or IP and Port into the Via header field.

I dont see an UAC inserting a sent-by in the VIA header.Normally a VIA header would look like this,

INVITE sip:bob at biloxi.com SIP/2.0
Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKnashds8
Max-Forwards: 70
To: Bob <sip:bob at biloxi.com>
From: Alice <sip:alice at atlanta.com>;tag=1928301774

The above VIA with Default port as 5060,transport as UDP and PC33.atlanta.com as FQDN is sufficient enough to send the response back to the client in case of any connection error or Transport error encountered at the server.

Can any one explain the Significance of sent-by.

Thanks in Advance










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[Dale Worley]

Post by innovation.interops
RFC 3261 says Before a request is sent, the client
transport MUST insert a value of the "sent-by" field with
FQDN or IP and Port into the Via header field.
Via: SIP/2.0/UDP pc33.atlanta.com;branch=z9hG4bKnashds8

The portion "pc33.atlanta.com" is called the "sent-by field". Compare with
the BNF rules "Via" and "via-parm" in section 25.1 of RFC 3261.

Dale