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10-23
Cisco ONS 15454 SDH Reference Manual, R5.0
April 2008
Chapter 10 Circuits and Tunnels
10.14.2 Software-Link Capacity Adjustment
constraints for individual members; with manual routing, you can select different spans for different
members. The FC_MR-4 and ML-Series cards support common fiber routing. In common fiber routing,
all VCAT members travel on the same fibers, which eliminates delay between members. Three protection
options are available for common fiber routing: Fully Protected, PCA, and Unprotected. Each member
can use a different protection scheme; however, CTC checks the combination to make sure a valid route
exists and if it does not, the user must modify the protection type. Figure 10-11 shows an example of
common fiber routing.
Figure 10-11 VCAT Common Fiber Routing
10.14.2 Software-Link Capacity Adjustment
The FC_MR-4 (enhanced mode), ML100T, and ML-1000 cards support Software–Link Capacity
Adjustment Scheme (SW-LCAS), which uses legacy SONET failure indicators like the AIS-P and RDI-P
to detect member failure. If used, SW-LCAS removes the failed member from the VCAT circuit for the
duration of the failure, leaving the remaining members to carry the traffic. When the failure clears, the
member circuit is added back into the VCAT circuit. SW-LCAS cannot autonomously remove members
that have defects in the H4/Z7 byte. SW-LCAS is only available for legacy SONET defects such as
AIS-P, LOP-P, etc. SW-LCAS is optional. You can select SW-LCAS during VCAT circuit creation. The
FC_MR-4 card in line rate mode does not support SW-LCAS.
SW-LCAS allows circuit pairing for ML-Series cards over two-fiber MS-SPRing. With circuit pairing,
a VCAT circuit is set up between two ML-Series cards: one is a protected circuit (line protection) and
the other is PCA. For four-fiber MS-SPRing, member protection cannot be mixed.
In addition, you can create non-LCAS VCAT circuits, which do not use SW-LCAS. While SW-LCAS
member cross-connects can be in different service states, all In Group non-LCAS members must have
cross-connects in the same service state. A non-LCAS circuit can mix Out of Group and In Group
members, as long as the In Group members are in the same service state. Non-LCAS members do not
support the Locked-enabled,outOfGroup service state; to put a non-LCAS member in the Out of Group
VCAT state, use Locked-enabled,disabled.
10.14.3 VCAT Circuit Size
Table 10-12 lists supported circuit rates and number of members for each card.
Member 1
VCG-2
Member 2
124265
Intermediate
NE
Member 1
VCG-1
Member 2
Member 1
VCG-2
Member 2
Member 1
VCG-1
Member 2
VCAT
Function
VCAT
Function
VCAT
Function
VCAT
Function
VC-1
VC-2
VC-3
VC-4
VC-1
VC-2
VC-3
VC-4
ML-Series ML-Series