Proxy E should forward the request. This has been explained numerous times already in this thread, but I'll summarise the key points again.
1. A Proxy checks for Max-Forwards:0 when it receives a message. 2. A Proxy does not check for Max-Forwards:0 when it sends a message. 3. A User Agent does not check Max-Forwards at all. Your argument that Proxy E should reject the message because it has already visited 5 nodes is incorrect. It should only be rejected if it was received with Max-Forwards:0. Note also that the header is called 'Max-Forwards' and not 'Max-Hops' or 'Max-Nodes'. Proxies engage in forwarding, but UAs do not. Michael > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:sip-implementors- > [EMAIL PROTECTED] On 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 > > > > > > > > _______________________________________________ > 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
