Hi,
There are a couple of thoughts we have regarding H.323 robustness:
1) As specified in TD87 from the Geneva meeting, "status inquiry" and "status" messages are used to resync call states. This may lead to a tremendous amount of load at the gatekeeper. A gatekeeper routed call requires 2 status inquiries and 2 status messages, plus the messages needed to re-establish the TCP connections. For a gatekeeper handling several thousand calls, this is a lot of messages.
2) Besides considering SCTP, have we considered modifying Annex E procedures to achieve robustness at network interface? If a NIC on a gatekeeper fails, endpoints trying to contact the gatekeeper could use a recovery address on another NIC to resend their messages. Is there any reason why this cannot be done or is undesirable? Such approach avoids invoking the procedures mentioned in TD87 to re-synchronize call states and to re-establish TCP connections. Since we are proposing a new set of procedures for a 323 entity to support robustness, backward compatibility doesn't seem like a problem.
Thanks.
Regards, Tim
------------------------------------------------------------ Tim Chen Trillium Digital Systems, Inc. Phone: +1 310 442 9222 Fax: +1 310 442 1162 email: tim@trillium.com http://www.trillium.com