2 – Theory of Operation
T1 CrossConnect Installation & Operation Manual
Version 2
GatesAir
2-13
Intraplex Products
Figure 2-12. Counter-rotating Ring Configuration after Failure between Sites C and D
2.4.2.3 Unidirectional versus Counter-Rotating Rings
Unidirectional rings guarantee a total of 24 circuits. This is because each circuit, regardless of length
or number of nodes traversed, requires dedication of a time slot all the way around the ring.
Counter-rotating rings, on the other hand, can provide far more than 24 circuits in a ring, if the
circuits are short hops. The maximum number of circuits which can be provided over a single T1
counter-rotating ring is realized in the (unlikely) case where all the circuits are single-hop connections.
Each time slot can be re-used for additional circuits in each segment of the ring. Since 12 of the time
slots must be left empty for protection switching capacity, the maximum number of circuits is 12 times
the number of sites in the ring. A six-site counter-rotating ring, for example, could provide (12 x 6) or
72 single-hop circuits. A ten-site counter-rotating ring could provide up to (12 x 10) or 120 single-hop
circuits. In either of these cases, a unidirectional ring would be limited to 24 circuits. Clearly for
networks which are dominated by short runs, or for large rings with many nodes, the counter-rotating
ring is very likely to provide the best bandwidth efficiency.
Summary of Contents for Intraplex T1 DCS-9530 CrossConnect System
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