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VoIP gateway IP400 version 5.01
A number of VoIP devices do not support the RAS protocol. Such devices can nev-
ertheless still be managed by being configured statically (hence with fixed IP
addresses) in the gatekeeper. Steps 1 and 2 then no longer apply in the sequence
in Fig. 19 on page 69. Such devices are configured in
Gateway
or
Gateway
group
mode.
Of course, your gateway itself can also log on to another gatekeeper with RAS pro-
tocol as illustrated in Fig. 20 on page 71. This operating mode is configured in
Registration at Gatekeeper as endpoint
or
Registration at Gatekeeper as
Gateway
mode.
6.1.2 Gatekeeper discovery
Gatekeeper discovery
works via
IP multicast
packets which a gatekeeper
client transmits if it wants to find a suitable gatekeeper.
Normally, such packets are only transmitted within one's own LAN segment and,
in particular, are not routed into other networks. That is why gatekeepers can only
be found within one's own LAN segment. However, routers can be configured so
that they transfer such packets according to certain rules. This makes it possible
to also find gatekeepers which are connected via WAN links.
The difference made is based on the so called
multicast addresses
. The
mul-
ticast address
used for
gatekeeper discovery
is
224.0.1.41
.
6.1.3 The Gatekeeper ID
Each gatekeeper within a network can be identified by means of its own
Gate-
keeper ID
. This ID allows the administrator to operate a number of gatekeepers
in parallel within a network, with each terminal nevertheless identifying the “cor-
rect” gatekeeper by means of
gatekeeper discovery
. The ID is defined directly
in the configuration applet in the
Gatekeeper ID
field within the
VoIP Inter-
faces
area.
If you have assigned your gateway a gatekeeper ID, it will only answer those
RAS
Discovery
inquiries in which either this ID or no
Gatekeeper ID
at all is speci-
fied. Even if your terminals have configured the gatekeeper permanently and
therefore do not perform
gatekeeper discovery
, the RAS registrations are again
only accepted if they include the configuration of the correct gatekeeper ID or of
no gatekeeper ID at all.
A configured
Gatekeeper ID
applies to the entire gateway.
In general, you can operate without
Gatekeeper ID
if only one gatekeeper is
operated in your network or if
Gatekeeper discovery
is not used.