If I may interject.
message leaves UA1 with mf=5,
leaves proxy A with mf=4
leaves proxy B with mf=3
leaves proxy C with mf=2
leaves proxy D with mf=1
so it arrives at Proxy E with mf=1
So it would be forwarded to UA2 with mf=0.
You look at the Max-Forwards when you receive it
not as you're about to send it.
Another way of understanding it is "it's the maximum
number of times a message will be forwarded".
Since only proxies are forwarding messages, it means
that Max-Forwards is actually equal to the maximum
number of proxies that can be traversed.
So, with 5 proxies (A to E), the message will
get to UA2 with Max-Forwards=0.
Regards,
Attila
>> -----Original Message-----
>> From: [EMAIL PROTECTED]
>> [mailto:[EMAIL PROTECTED] Behalf
>> Of Subramanya
>> Sent: 15 November 2006 14:30
>> To: Kasturi Narayanan
>> Cc: ysong; sip-implementors
>> Subject: Re: [Sip-implementors] FW: Query on max-forwards counts
>>
>>
>> When a request reaches the proxy, if mf becomes 0 once proxy
>> decrements
>> the mf,then it means it has already hopped n number of times
>> right, then
>> why proxy should send to next hop.
>>
>> i mean, see this example where mf is 5
>> mf=5 mf =4 mf =3 mf =2 mf =1
>> mf =0
>> UA1--> Proxy A--> Proxy B--> Proxy C-->Proxy D--> Proxy E-->UA2
>>
>> Now at Proxy E mf is 0, means it has already visited 5 nodes, so it
>> shdn't be forwarded anymore,so proxy E shd return with 483 response.
>>
>> Please correct me if i am wrong.
>>
>> -Subramanya
>>
>>
>> Kasturi Narayanan wrote:
>> > The approach suggested by Robert Sparks solves the problem
>> but creates an un-necessary hop when the sender knows for
>> sure that it going to be dropped by the Receiver (since it
>> is sending with mf=0).
>> >
>> > Kasturi
>> >
>> > -----Original Message-----
>> > From: Song, Youngsun [mailto:[EMAIL PROTECTED]
>> > Sent: Monday, November 13, 2006 9:22 AM
>> > To: [email protected]
>> > Subject: [Sip-implementors] FW: Query on max-forwards counts
>> >
>> > Hi,
>> >
>> > Please see the attached response from Robert Sparks regarding this
>> > query. (FYI, I had also sent him a separate email...)
>> > Per his response, Proxy-B should forward the request to UA-B.
>> >
>> > Thanks to all who has taken the time to respond to my query,
>> > YoungSun
>> >
>> >
>> >
>> >> -----Original Message-----
>> >> From: Robert Sparks [mailto:[EMAIL PROTECTED]
>> >> Sent: Monday, November 13, 2006 9:12 AM
>> >> To: Song, Youngsun
>> >> Subject: Re: [Sip-implementors] Query on max-forwards counts
>> >>
>> >> See page 95, item 3.
>> >>
>> >> You reject when you receive, not before you send.
>> >> You reject when you receive a max-forwards of 0, not when you
>> >> receive a max-forwards of 1.
>> >>
>> >> RjS
>> >>
>> >>
>> >>>>> -----Original Message-----
>> >>>>>
>> >>>> From: [EMAIL PROTECTED]
>> >>>> [mailto:[EMAIL PROTECTED] On
>> >>>>
>> >> Behalf Of Song,
>> >>
>> >>>> Youngsun
>> >>>> Sent: Friday, November 10, 2006 11:19 AM
>> >>>> To: [email protected]
>> >>>> Subject: [Sip-implementors] Query on max-forwards counts
>> >>>>
>> >>>> Hi,
>> >>>>
>> >>>> I have a clarification question on the following statement
>> >>>>
>> >> in Section
>> >>
>> >>>> 8.1.1.6 of RFC3261 regarding when a proxy should send a 483 and
>> >>>> whether the number of hops includes the destination hop.
>> >>>>
>> >>>> "The Max-Forwards header field serves to limit the number
>> >>>>
>> >> of hops a
>> >>
>> >>>> request can transit on the way to its destination. It
>> >>>>
>> >> consists of an
>> >>
>> >>>> integer that is decremented by one at each hop. If the
>> >>>>
>> >> Max-Forwards
>> >>
>> >>>> value reaches 0 before the request reaches its
>> >>>>
>> >> destination, it will
>> >>
>> >>>> be rejected with a 483(Too Many Hops) error response."
>> >>>>
>> >>>>
>> >>>> Consider the following flow: (mf=max-forwards)
>> >>>>
>> >>>>
>> >>>> UA-A --- INVITE (mf=2) ---> Proxy-A ---- INVITE (mf=1)
>> >>>>
>> >> ---> Proxy-B
>> >>
>> >>>> ---- INVITE (mf=0) ---> UA-B
>> >>>>
>> >>>>
>> >>>> In the flow above, should Proxy-B forward the INVITE with
>> >>>> max-forwards=0 to UA-B or should it reject the request with 483?
>> >>>>
>> >>>> Thanks for your help in advance,
>> >>>> YoungSun
>> >>>>
>> >>>> _______________________________________________
>> >>>> Sip-implementors mailing list
>> >>>> [email protected]
>> >>>>
>> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>> >>>>
>> >>>>
>> >>
>> >
>> > _______________________________________________
>> > Sip-implementors mailing list
>> > [email protected]
>> > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>> >
>> >
>> > _______________________________________________
>> > Sip-implementors mailing list
>> > [email protected]
>> > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
>> >
>> >
>> >
>>
>> _______________________________________________
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>> [email protected]
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>>
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