True, UDP flow may not be required if TCP flow has been setup to route incoming traffic towards UA. But Won't it be an additional bonus if UA creates a UDP FLOW in addition to TCP FLOW, so that network can still reach the UA over the other transport FLOW when one FLOW is down (Unless if both FLOWs got created with same host and all the FLOWs connected to that host is down)? Also assume a UA has some local policy to prefer UDP transport over TCP to transmit the outgoing SIP messages of size less than MTU. In such scenarios, UA might want to establish both UDP and TCP FLOWs with the same edge proxy and keep alive both the connections and use the corresponding FLOW based on DNS lookup preferences and User's local policy preferences to transport outgoing messages.
________________________________ From: Francois Audet [mailto:au...@nortel.com] Sent: Saturday, August 29, 2009 12:23 AM To: Vavilapalli Srikanth-A19563; s...@ietf.org; s...@core3.amsl.com; sip-implementors@lists.cs.columbia.edu Subject: RE: [Sip] Question on draft-ietf-sip-outbound-20 draft: multipleflowcreation I honestly don't know why anybody would want to do both UDP and TCP. (In other words, if you set up a TCP flow, I don't see a benefit in also setting up a UDP flow which you will have to maintain for keep alives). ________________________________ From: sip-boun...@ietf.org [mailto:sip-boun...@ietf.org] On Behalf Of Vavilapalli Srikanth-A19563 Sent: Friday, August 28, 2009 07:46 To: Audet, Francois (SC100:3055); s...@ietf.org; s...@core3.amsl.com; sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip] Question on draft-ietf-sip-outbound-20 draft: multipleflowcreation Hi Thanks for the reply..One more of clarification required.. So If UA wishes to create multiple transport flows with "sip:primary.example.com"(As specified in draft-ietf-sip-outbound-20#section-13 to honor RFC3261 requirement for message size greater than MTU), would it be OK it one FLOW lands on Host1 and other FLOW lands on Host2? i.e for example if "sip:primary.example.com" got resolved into (IP1, Port1, TCP) -> (IP2, Port2, TCP) -> (IP2, Port2, UDP) -> (IP1, Port1, UDP) in that order, and if UA wises to create both TCP and UDP FLOWs with "sip:primary.example.com", then it starts creating TCP FLOW with (IP1, Port1, TCP) and can create a UDP FLOW with (IP2, Port2, UDP) based on RFC 3263 procedures. Is my understanding correct here? In the above example, if (IP1) is down/crashed for some reasons, then "sip:primary.example.com", can never use the TCP FLOW for transporting inbound messages to that UA (Even though the IP1 and IP2 are state synchronized) until User Agent detects the FLOW failure with (IP1) and re-create the TCP FLOW with (IP1 or IP2). Is my understanding correct here? Please clarify.. Regard Srikanth ________________________________ From: Francois Audet [mailto:au...@nortel.com] Sent: Thursday, August 27, 2009 9:22 PM To: Vavilapalli Srikanth-A19563; s...@ietf.org Subject: RE: [Sip] Question on draft-ietf-sip-outbound-20 draft: multiple flowcreation You would have 2. One for primary, and one for secondary. For each one of those, you would use normal RFC 3263 procedures for determining which SRV record to use. ________________________________ From: sip-boun...@ietf.org [mailto:sip-boun...@ietf.org] On Behalf Of Vavilapalli Srikanth-A19563 Sent: Thursday, August 27, 2009 07:57 To: s...@ietf.org Subject: [Sip] Question on draft-ietf-sip-outbound-20 draft: multiple flowcreation Hi As specified in section 3.3/3.4 of draft-ietf-sip-outbound-20 draft, If a UA is configured with a outbound-proxy-set with two proxy uris: "sip:primary.example.com" and "sip:secondary.example.com" And for example, "sip:primary.example.com" got DNS resolved in to two SRV records "Host1" and "Host2" and "sip:secondary.example.com" got DNS resolved in to "Host3" and "Host4", Should UA create four FLOWs, One with each host OR just two FLOWs, one with each proxy URI(i.e one flow with either Host1 or Host2 and second flow with Host3 or Host4)? Please clarify. Regards Srikanth _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
