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Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2
78-19417-01
Chapter 7 Circuits and Tunnels
Virtual Concatenated Circuits
Figure 7-4 shows an example of split fiber routing.
Figure 7-4 VCAT Split Fiber Routing
Note The switch time values shown in Table 7-5 does not include differential delay. The maximum
differential delay for CE100T-8 is 48ms. This differential delay is added to the switch time to
get the maximum time.
7.7.3 Link Capacity Adjustment
The CE-100T-8, CE-MR-6, and ML-100T-8 cards support the Link Capacity Adjustment Scheme
(LCAS), which is a signaling protocol that allows dynamic bandwidth adjustment of VCAT circuits.
When a member fails, LCAS temporarily 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 automatically added back into the VCAT circuit. You can select LCAS during VCAT
circuit creation.
124065
VCAT
Function
Source VCAT at NE
Traffic Traffic
Virtually
Concatenated
Group Member #1
Member #2
Member #3
Intermediate
NE
VCAT
Function
with
Differential
Delay Buffer
Destination VCAT at NE
Intermediate
NE
Intermediate
NE
Table 7-5 Switch Times
Type of circuit For CE100T-8 card For CE-MR-6 card
CCAT 60 ms 60 ms
HO VCAT 60 ms 90 ms
HO LCAS190 ms 148 ms
LO VCAT 202 ms 202 ms
LO LCAS 202 m 256 ms
SWLCAS — 500 ms
1. The calculated number for HO LCAS includes all the inherent delays of the protocol. Also the CE-100-T
numbers are for a group size of only three members.