Switchback; Mgcp Gateway Fallback - Cisco VGD-1T3 Software Configuration Manual

Configuring MGCP Gateway Support

Switchback

Switchback is the process a voice gateway uses to reestablish communication with the primary
Cisco Unified Communications Manager server when the server becomes available again. Switchback
can occur immediately, at a specified time after the last active call ends, or after a specified length of
time.

MGCP Gateway Fallback

The MGCP gateway maintains a remote connection to a centralized Cisco Unified Communications
Manager cluster by sending MGCP keepalive messages to the Cisco Unified Communications Manager
server at 15-second intervals. If the active Cisco Unified Communications Manager server fails to
acknowledge receipt of the keepalive message within 30 seconds, the gateway attempts to switch over
to the next available Cisco Unified Communications Manager server.
If none of the Cisco Unified Communications Manager servers respond, the gateway switches into
fallback mode and reverts to the default H.323 session application for basic call control. H.323 is a
standardized communication protocol that enables dissimilar devices to communicate with each other
through use of a common set of codecs, call setup and negotiating procedures, and basic data transport
methods. The gateway processes calls on its own using H.323 until one of the Cisco Unified
Communications Manager connections is restored.
Figure 2
Figure 2
Communications Manager
Remote site A
The MGCP Gateway Fallback feature provides the following functionality:
Cisco VGD 1T3 Voice Gateway Software Configuration Guide
124
illustrates a typical VoIP network topology in which MGCP gateway fallback is supported.
Typical VoIP Network Topology Supporting the MGCP Gateway Fallback Feature
Cisco Unified
Communications Manager
1
Cisco Unified
M
cluster
LAN
MGCP/H323
Cisco
router
IP
IP phones
T1/E1 PRI
FXS
POTS
POTS
Using Cisco Unified Communications Manager to Configure MGCP Gateway Support
Cisco Unified
Communications Manager
2 Cisco Unified
Communications Manager
M
3
M
LAN
WAN
LAN
MGCP/H323
Cisco
router
IP phones
T1-CAS
FXO
PBX PBX phone
Remote site B
PSTN
IP