Gary,
Generally I think your editorial intervention has been good. However, the state reset to when an non-empty capability set is received should be the state that H.245 is in after H.245 is originally established, NOT the state before the pause is invoked. This flushes out any H.245 state so that you have a known state to which to connect to a new endpoint. Some attempt at words is:
On reception of a non-empty capability set in this paused state an endpoint shall reset its H.245 state to that which it is in just after the H.245 transport connection is made at call establishment time (i.e. the beginning of phase B).
Hope this helps,
Pete ================================= Pete Cordell BT Labs E-Mail: pete.cordell@bt-sys.bt.co.uk Tel: +44 1473 646436 Fax: +44 1473 645499 =================================
From: gthom[SMTP:gthom@DELTA-INFO.COM] Sent: 19 September 1997 19:47 To: ITU-SG16@mailbag.jf.intel.com Subject: TD-27 text for h.323
Pete and others,
I took some editorial liberty with the text of TD-27. It is contained below. I expect to put this in 6.2.8.1 Capability Exchange. Alternatively, I could put it into 8.2. Any suggestions, changes, clarifications???
Thanks Gary
"To allow gatekeepers to re-route connections from endpoints that do not support supplementary services, endpoints shall support the reception of empty capability sets (i.e. Terminal Capability sets that indicate that the endpoint sending the message has no receive capabilities). This feature also allows 'network' elements such as PBXs, call centers, and IVR systems to re-route connections independent of supplementary services and facilitates pre-connect announcements. It can also be used to delay H.245 media establishment when features such as Gatekeeper based user location is being used. It is also highly recommended that Version 1 endpoints support this feature.
On reception of an empty capability set an endpoint shall enter a paused state. If media stream or data logical channels were previously opened by the endpoint, they should be closed. In this state an endpoint shall accept the opening of logical channels from the remote end based on the usual rules and continue to receive media from open logical channels from the remote end. This allows endpoints to receive announcements (e.g. pre-connect call progress) where the announcing entity does not wish to receive media from the endpoint.
On reception of a non-empty capability set in this paused state an endpoint shall reset its H.245 state to that which it was in prior to entering the paused state. This allows an endpoint to be connected to a different endpoint when it is released from the paused state. Note that the non-empty capability set shall not be sent to an endpoint until all its transmit and receive logical channels have been closed. A switching entity should also send an H.450 redirection indication Facility message if the endpoint is being re-routed. The endpoint shall then proceed with normal H.245 connection establishment signalling. When leaving the paused state an endpoint shall take part in master/slave determination signalling, and may proceed with normal open logical channel signalling procedures. When an MC receives a release from the paused state it shall act as if a new endpoint has entered the conference.
Unless its capabilities have changed, an endpoint need not resend a capability set as the gatekeeper will have supplied this to remove any paused state in the remote endpoint. This option of not sending a capability set enables faster reconnection.
Name: Gary Thom Company: Delta Information Systems, Inc. Phone: +1-215-657-5270 x23 Fax : +1-215-657-5273 E-mail: gthom@delta-info.com Date: 09/19/97 Time: 11:47:19