Primary Data Connectivity; Isdn-Pri Trunk Groups And Channel Allocation - Avaya Communication Manager Administrator's Manual

Primary data connectivity

Permanent data connections (those always active during business hours), such as
interconnections between LANs, are well suited for Avaya Communication Manager when
ISDN-PRI endpoints are used. The ISDN end-to-end monitoring and the endpoint's ability to
react to failures provide for critical data availability needs. With ISDN, endpoints can detect
network failures and initiate backup connections through the server running Communication
Manager; ISDN endpoints can also establish additional calls when extra bandwidth is needed.
Any failures not automatically restored by Avaya Communication Manager are signaled to the
endpoint application, which can initiate backup data connections over the same PRI endpoint.
Communication Manager routes the backup data connections over alternate facilities if
necessary.
Networking
All of the wideband networking is over ISDN-PRI facilities (and the emulation of them by
ATM-CES) but might connect to a variety of networks, other domestic interexchange carriers'
services, private line, RBOC services, and services in other countries.
ISDN-PRI trunk groups and channel
allocation
Only ISDN-PRI trunks (and the emulation of them by ATM-CES) support wideband calls to the
network. Wideband's bandwidth requirements have necessitated modification of the algorithms
by which trunks look for idle channels. The following section describes the search methods and
their relationship to the available wideband data services.
Facility lists
The system always sends a wideband call over a single trunk group and a single DS1 facility (or
other ISDN-PRI-capable facility). Since a trunk group can contain channels (trunk members)
from several different DS1 facilities, the system maintains a facility list for each trunk group.
A facility list orders the trunk members based on signaling group. If the system is using
non-facility associated signaling groups with multiple DS1 facilities, the system sorts trunk
members in that signaling group according to the interface identifier assigned to the
corresponding DS1 facility.
When searching for available channels for a wideband call placed over a given trunk group, the
system starts with the channels in the lowest-numbered signaling group with the lowest
interface identifier. If the system cannot find enough channels in a given signaling group with
that interface identifier, it checks the next higher interface identifier. If no more interface
identifiers are available in the current signaling group, the system moves its search to the
channels in the next higher signaling group.
Wideband Switching
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