Information Technology Reference
In-Depth Information
There are many types of H.225 RAS messages:
■
Gatekeeper discovery:
Used by endpoints to find a gatekeeper with which to register. Specific gatekeeper discovery
messages include GRQ, Gatekeeper Confirm (GCF), and Gatekeeper Reject (GRJ).
■
Registration and unregistration:
This process is used by endpoints and other devices to register their addresses with
gatekeepers and join a zone. Registration and unregistration messages include Registration Request (RRQ), Registration
Confirm (RCF), Registration Reject (RRJ), Unregister Request (URQ), Unregister Confirm (UCF), and Unregister Reject
(URJ).
■
Admission control:
These messages are used for CAC and bandwidth management. Specific message types include
Admission Request (ARQ), Admission Confirm (ACF), and Admission Reject (ARJ).
■
Bandwidth control:
These messages can be used to change the amount of bandwidth during a call. Messages include
Bandwidth Request (BRQ), Bandwidth Confirm (BCF), and Bandwidth Reject (BRJ).
■
Endpoint location:
Used to retrieve contact information. Messages include Location Request (LRQ), Location Confirm
(LCF), and Location Reject (LRJ).
■
Status information:
Used to retrieve status information. Specific messages include Information Request (IRQ), and
Information Request Response (IRR).
Figure 3-5
illustrates H.225 RAS in relation to H.225 call control signaling and H.245 (assuming direct endpoint call signaling).
FIguRE 3-5
H.225 RAS, H.225 Call
Control, and H.245
Gatekeeper
H.225 Call Setup
H.323
Endpoint #1
H.323
Endpoint #2
H.245 Signaling
RTP/RTCP
