I have a question about VC4-4c failure. There is an ethernet circuit created on ONS1545 sized VC4-4c. In the middle of the network, the VC4-4c is separated transmitted as 4x individual VC4. What will happen if one individual VC4 fail? Will the whole circuit be torn down or just suffer loss of part of the bandwidth? Can the behavior be manipulated by configuration?
Viyuan700 brings up a good point. Rereading the original question, if the circuit is concatonated, then how could an individual VC4 fail or how could the concatonated VC4 be carried as individual VC4s in the middle of the network (some type of intermediate VC4-4c to VC4-4v mux)?. Yuyang Jin, do you have more details regarding the network? Maybe you are already deploying VC4-4v circuit between 15454 cards?
Good catch Viyuan700.
Tom is correct, but if you are using VCAT and LCAS at the end-points the circuit between will not be a VC4-4c. It will be 4 individual VC4 circuits that are stiched together by the VCAT/LCAS code. VCAT will make the 4 individual VC4 circuits look like a pipe the size of a VC4-4c. And if one VC4 fails, LCAS will take it out the failed VC4 leaving 3 VC4s still carrying traffic between the end-points.
In that case, the entire VC4-4c circuit will fail. There isn't a recovery mechanism for circuits built using standard concatenation.
If your Ethernet service cards in the 15454 support Virtual Concatenation (VCAT) and Link Capacity Adjustment Scheme (LCAS), then your Ethernet circuit can remain up even if one or more of the individual VC4 circuits go down. The Ethernet service cards act to bond together individual VC4s to create a VC4-4v circuit. The VC4s traverse the SDH network as 4 independent circuits. If one VC4 goes down, the Ethernet service card then adjusts for the loss, and operates as having only a 3 x VC4 trunk.
Many of the latest 15454 Ethernet cards support VCAT & LCAS.