H.323 Architecture - 3Com MSR 50 Series Configuration Manual

H.323 Architecture

Table 89 Major RAS messages
Category
Call disengage
Status information
Bandwidth control
Gateway resource availability
RAS timer modification
An H.323 network consists of terminals, voice gateways, an optional gatekeeper,
and multipoint control units (MCUs). If a gatekeeper is present in an H.323
network, the terminals, gateways, and MCUs registered with the gatekeeper form
a zone. In this zone, the gatekeeper provides the following functions for H.323
terminals, gateways, or MCUs:
Address translation
■
Admission control
■
Bandwidth control
■
Zone administration and security control
■
Call control signaling and call management
■
Routing control and accounting
■
Figure 681 shows a simple H.323 network. For all calls, a gatekeeper is the call
service control and central control unit in its administrative zone.
Gateway entities are usually deployed on routers. You may configure the IP voice
gateway function on the router at command line interface (CLI). They interact with
gatekeepers by sending H.225.0 RAS messages.
In the current implementation, gatekeepers are usually deployed on SUN stations
or servers while gateways are deployed on routers. For reliability sake, a backup
mechanism is provided for gatekeepers. In case the communication with a primary
gatekeeper is abnormal (for example, timeout occurs) or the primary gatekeeper
becomes unavailable, gateways can turn to a secondary gatekeeper for
registration.
H.323 Architecture
Message
DRQ (Disengage_Request)
DCF (Disengage_Confirm)
DRJ (Disengage_Reject)
IRQ (Information_Request)
IRR (Information_Request_Response)
IACK (Info_Request_Acknowledge)
INAK (Info_Request_Neg_Acknowledge)
BRQ (Bandwidth_Request)
BCF (Bandwidth_Confirm)
BRJ (Bandwidth_Reject)
RAI (Resource Availability Indicator)
RAC (Resource Availability Confirm)
RIP
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