Comments inline. -Rockson -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Lawrence Sent: Friday, June 27, 2008 12:41 AM To: Vivek Batra Cc: [email protected] Subject: Re: [Sip-implementors] SIP client registers from multiple locationsand all location are behind the NAT
On Thu, 2008-06-26 at 15:29 +0530, Vivek Batra wrote: > Please consider the following: > * SIP client send the REGISTER message to Registrar server from > multiple locations. Q-value is not send by SIP client in its REGISTER > request. > * Registrar server sends the 200 OK to the SIP client with all the > binding for this user along with expiry timer for each binding. > * SIP client selects its own binding to get expiry timer allocated by > Registrar server. > * But if all the SIP clients are located behind the NAT (in different > LAN networks) and same IP address is assigned to each SIP client > suppose 192.168.1.1, all SIP client will send the IP:Port viz 192.168.1.1:5060. [Rockson] I think the 192.168.1.1:5060 is just the source address in IP level, which does not relate to SIP contact url. > * Now when 200 OK is send by Registrar server to SIP client, all the > bindings in 200 OK includes the same IP address. Now, what should be > the implementation in SIP client to select its own binding since all > the bindings shall have same IP:Port. The UA should construct its Contact with some unique value in it so that it can recognize it among the choices. Stick a url parameter on it that's randomly chosen or something; don't rely on the IP address to be the identifier. [Rockson] if the Contact is not changed , which is still what your sip client put into, the incoming request would go to this address, which is probably not feasible, since this a private ip addr, this is why Scott suggest to use domain not ip addr. However, things might not so simple, NAT is more complex than you thought. You may need Symmetric Response RFC3581 and draft-ietf-sip-outbound -- Scott Lawrence tel:+1.781.229.0533;ext=162 or sip:[EMAIL PROTECTED] sipXecs project coordinator - SIPfoundry http://www.sipfoundry.org/sipXecs CTO, Voice Solutions - Bluesocket Inc. http://www.bluesocket.com/ http://www.pingtel.com/ _______________________________________________ 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
