2 – Theory of Operation
T1 CrossConnect Installation & Operation Manual
Version 2
GatesAir
2-9
Intraplex Products
Figure 2-8. Single T1 Ring Configuration
On detection of a failure or degradation in any one of the T1 links, the two CrossConnect Systems
connected to that T1 each initiate a map-switch action. The manner in which the maps are
preprogrammed determines the route each T1 time slot takes around the ring before and after the
failure event. Two different approaches can be taken to programming the maps, resulting in either a
unidirectional ring configuration or a counter-rotating ring configuration. The physical equipment and
T1 connections are identical for each of these rings. However, based on the expected traffic patterns
in the network, one configuration or the other may prove more efficient in use of available T1 capacity
around the ring.
2.4.2.1 Unidirectional Rings
In unidirectional rings, the traffic under normal (pre-failure) conditions always proceeds around the
ring in a single direction. Figure 2-9 shows this type of ring. All the normal traffic is on the outer path
moving in a clockwise direction around the ring. If a circuit is needed, for example, between sites A
and B, traffic flows from site A in a clockwise direction to site B. The return traffic, however, travels
the long way around the ring from site B through sites C and D back to site A. Since all standard T1
lines are bi-directional, this configuration leaves a completely unused path (the inner ring) in the
Summary of Contents for Intraplex T1 DCS-9530 CrossConnect System
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