User`s manual

MP-1xx/H.323 User’s Manual 5. Profiling & Operation
Version 4.2 Beta 45 June 2003
5.3 Alternate (Redundant) GK Implementation
1. The MP-1xx Gateway doesn’t support Automate Gatekeeper discovery. Gatekeeper address
is provided through initialization file (or via Web management). In AudioCodes, this
procedure is referred to as “Redundant Gatekeeper” procedure. In general, it is identical to
Alternate procedure described in H.323 standard, with the exception that the list of primary
and alternate Gatekeepers is provided via initialization file.
2. In addition to primary Gatekeeper address, it is possible to provide list of two additional,
“Alternate” Gatekeeper addresses, using the same initialization file.
3. Working with primary and alternate gatekeepers is according to procedure described in the
H.323 standard (para. 7.2.6 Alternate gatekeeper procedures), with the exception that all
Alternate Gatekeeper fields in RAS messages are ignored.
4. According to H.323, para 7.2.6 procedure, the MP-1xx Gateway supports the following:
" Endpoint attempts to register with the Gatekeeper using the list of Alternate Gatekeepers.
" If the endpoint is registered with the Gatekeeper and the Gatekeeper becomes
unresponsive, the endpoint shall attempt to communicate with an Alternate Gatekeeper.
" If the endpoint determines that a temporary Alternate Gatekeeper is unresponsive, it
attempts to retransmit the RAS request to another Alternate Gatekeeper. If all Alternate
Gatekeepers are unresponsive to a RAS request, the endpoint assumes that the RAS
request is rejected.
5. If an MP-1xx Gateway finds an alternative Gatekeeper from the list of alternate
Gatekeepers, it registers with this Gatekeeper and continues working with it until next failure
(current GK is not responding).
6. If all Gatekeepers are unresponsive, the MP-1xx Gateway tries again to establish
communication, and to register to the first gatekeeper according to the provisioned
Gatekeeper list.
7. The MP-1xx Gateway has an option to use internal phone to IP routing table (Fallback
mode), when all Alternative Gatekeepers are unresponsive. If this option is enabled, MP-1xx
starts using its internal routing table, and works without Gatekeeper. The MP-1xx leaves this
Fallback mode as soon as it finds again a responsive Gatekeeper from its list of the
Gatekeepers.
8. Alternate Gatekeeper, using RAS IRQ message, can retrieve the state of existing calls. The
MP-1xx Gateway responds via IRR message.