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Cisco MGX 8230 Edge Concentrator Installation and Configuration
Release 1.1.31, Part Number 78-11215-03 Rev. B0, May 2001
Chapter2 Module and Service Descriptions Frame Relay Service Modules
MGCP 0.1 for VoIP with Softswitch Control
VISM supports Media Gateway Control Protocol (MGCP) Version 0.1. This open protocol allows any
Softswitch to interwork w it h the VISM module.
Resource Coordination via SRCP
Simple Resource Control Protocol (SRCP) provides a heartbeat mechanism between the VISM and the
Softswitch. In addition, SRCP also provides the Softswitch with gateway auditing capabilities.
Full COT Functions
VISM provides the capabilit y to initiate continuity tes t a s w el l a s provide loopbacks to facili tat e
continuity tests when orig in at ed f ro m t h e fa r-e nd .
Courtesy Down
This feature provides a mechanism for graceful upgrades. By enabling this feature, no new calls are
allowed on the VISM while not disr up ti ng th e exis t in g call s. Eventually, when there are no more active
calls, the card is ready for a upgrade and/or service interruption.
PRI Backhaul to the Softswitch Using RUDP
The PRI backhaul capabili ty pr ov ides PRI termination on the V I S M wi th the Softswitch providin g c all
control. ISDN Layer 2 is terminated on the VISM and the layer 3 messages are transported to the
Softswitch using RUDP.
Latency Reduction (<60 ms round-trip)
Significant improvements have been made to bring the round-trip delay to less than 60 ms.
Codecs Preference
VISM provides the capability to have the codecs negotiated between th e two end-points of the call. The
VISM can be configured, for a given end-point, to have a prioritized list of codecs. Codec negotiation
could be directly between the en d-p oi nt s o r co ul d b e co nt rol led by a S ofts wi tch
31 DS0 for E1 with 240 Channels Only
While all 31 DS0s on a E1 port can be used, there is a limitation of 240 channels per card.
VISM Redundancy
The VISM redundancy strategy is the same as for any of the eight port cards in the MGX 8230.
•For VISM-8T1, 1:N redundancy is supported using the SRM-3T3.
•For VISM-8E1, 1:N redundancy is supported only via LMs using the SRM-3T3 or the SRM-T1E1.
Card Combinations
A card set has an V ISM -8T1 or VISM-8E1 f r ont card and one of t he following back card s:
•AX-RJ48-8T1-LM
•AX-R-RJ48-8T1-LM (for redundancy support)
•AX-RJ48-8E1-LM
•AX-SMB-8E1-LM
•AX-R-SMB-8E1-LM (for redundancy support)