[SIPForum-discussion] Max forwards geting added by proxies

[Gottfried, Hal F]

Vijay -
I believe the wordings of the RFC are slightly ambiguous when it comes to the use of the Max-Forwards field.  There was a time when this field was optional although now it has become mandatory. Max-Forwards limits the number of hops a request can make on the way to its destination. It consists of an integer, normally 70 that is decremented by one at each hop. If the Max-Forwards value reaches 0 before the request reaches its destination, it is rejected with a 483 (Too Many Hops) error response.

The real use behind the Max-Forwards mechanism is in that it allows the preventing of a message from entering into an endless loop between a set of proxies.

I hope this helps.

Hal F. Gottfried
Sr Consultant, Contact Center Consulting & Services

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Vijay Kumar
Sent: Tuesday, January 22, 2013 3:25 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Max forwards geting added by proxies

Agreed as per RFC 3261 Sec 8.1.1.6   " Max forward is Mandatory header feild in SIP Requests
UAC MUST insert it."

But as per 16.6

"If the copy does not contain a Max-Forwards header field, the proxy MUST add
one with a field value, which SHOULD be 70."

My questions
1.If MAx forwards is a Mandatory parameter then why should proxy add it.( If UAs are not able to add it).

2. As per 3261 if Max forward Is not added by UAC then SIP outbond proxy Must add Maxforward header feild.
    Can Max-forwarded be added by intermediate proxies as wel l???

(If yes i feel the  purpouse of Max forwards header feild  does not serve the purpose.)

Enlighten me please
Thanks in Advance
Vijay

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