I agree with Kasturi. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kasturi Narayanan Sent: Wednesday, November 15, 2006 10:57 AM To: a22587; michael.procter Cc: ysong; sip-implementors Subject: Re: [Sip-implementors] FW: Query on max-forwards counts
Michael, In the example below Proxy E received with MF=0. In this case should it return 483 was the question. Since Proxy E is going to do the Contact Routing it may/can ignore MF and route it. Kasturi -----Original Message----- From: Michael Procter [mailto:[EMAIL PROTECTED] Sent: Wednesday, November 15, 2006 9:08 AM To: Subramanya; Kasturi Narayanan Cc: ysong; sip-implementors Subject: RE: [Sip-implementors] FW: Query on max-forwards counts 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 This email and any attached files herein contain information that is intended only for the use of the individual or entity to whom it is addressed and may contain information that is legally privileged, confidential or otherwise exempt from disclosure under applicable laws. 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