Cisco Systems (VISM)

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Cisco VISM Installation and Configuration Guide

Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004

Chapter3 VISM Functional Description

Signaling Function

Figure 3-5 shows the VISM PRI/backhaul process.

Figure3-5 PRI/Backhaul Path

For RUDP links between VISM and the call agents, use a session with a session manager.

A session represents a single RUDP link to a specified call agent. Sessions are organized into session

groups, and session groups are organized into session sets. VISM architecture supports up to 64 sessions

and up to 16 session groups; however, Release 2.2 supports one session.

Multiple RUDP links for a specified call agent are set up as sessions in a single group. A group is

required for each call agent for which CCS signaling is to be backh au l ed. Within a gro up, ea ch ses sio n

is assigned a priority level. When an active session fails, the session manager switches to the next highest

priority backup session within the group. Figure 3-6 shows the hierarchy of RUDP sets, groups, and

sessions.

Figure3-6 RUDP Session Hierarchy

VISM maintains a set of counters for the collection of statistics at both the Q.921 and Q.931 protocol

levels. The collected statistics include the number of frames/packets/bytes sent and receiv ed, the number

of resets, the number of discards and retransmissions, etc. Refer to the C CS ses sion a nd L APD displa y

commands in Chapter 5, “CLI Commands,” for more information on collected statistics for the CCS

session and LAPD display commands.

MGX 8850

with VISM

Router

Call Agent

PBX

PRI Backhaul

Path

D channel

B channel Voice Payload

Packe

Netwo

Signaling

Network

44387

Session

Group 1

Sessions to

Call Agent A Sessions to

Call Agent B Sessions to

Call Agent C

Session

Set

Session

Group 2 Session

Group 3

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