>> my question was from a call statefull proxy point of view. >> how will a proxy see if both the End points are alive.?
If the proxy supports RFC4028, all it can do is rely on the UA-generated session refreshes to tell it that the call is still alive. So, in other words, a proxy cannot see if both end points are alive, it can only detect if the session has expired. So, if the call is between 2 UAs that don't support session timer, the proxy cannot determine if the session has expired. But in scenarios where one end supports the session timer, the proxy could still use the session timer mechanism. main points for SIP session timers and proxies: 1. proxies should record-route. 2. for requests, proxies can add a Session-Expires header if none present but MUST NOT include a refresher parameter. 3. for the request, it must not modify a refresher parameter. 4. if the request indicated "timer" was supported, then if the corresponding response did not contain "Session-Expires", then the proxy MUST insert a Session-Expires header field and it MUST set the value of the 'refresher' parameter to 'uac'. 5. When the session expiration is detected, the proxy can remove the call but it MUST NOT send a BYE. See section "8. Proxy Behavior" for all details. Regards, Attila >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] Behalf Of Arif >> Sent: 12 February 2007 13:20 >> To: [email protected] >> Subject: Re: [Sip-implementors] Question on Session Timers and TCP >> >> >> >> >>Not exactly sure what you mean by "this"? >> >>However, support for the SIP session timer feature (like >> most other >> >>features)is indicated in the SIP Supported or SIP Require header. >> >> >>If your UA supports SIP session timer but the other end >> does not, then >> >>your UA can still do periodic session refreshes on its >> own. But of >> >>course,the end which doesn't support session timer won't >> be able to detect if >> >>the connection has erroneously broken. >> >> thanx for the reply..a bit more clarification. >> my question was from a call statefull proxy point of view. >> how will a proxy see if both the End points are alive.? >> >> regards >> >> >> >> >> --------------------------------- >> Everyone is raving about the all-new Yahoo! Mail beta. >> _______________________________________________ >> 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
