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Cisco ONS 15600 SDH Reference Manual, Release 9.0
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Chapter 7 Circuits and Tunnels
7.16.2 VCAT Circuit Routing over Server Trails
7.16.2 VCAT Circuit Routing over Server Trails
An VC4-3c server trail can be used to route VC4-3c circuits and an VC4 server trail can be used to route
VC4 circuits. Similarly, a VC3 server trail can be used to route VC3 circuits.
For example, to route a VC4-3c-2v circuit over a server trail, you must enable split fiber routing and
create two VC4-3c server trails and route each member manually or automatically over each server trail.
To route a VC4-12c-2v circuit over a server trail, you must enable split fiber routing and create two VC4
server trails and route each member manually or automatically over each server trail.
Note
Server trails can only be created between any two optical ports or STM-1E ports.
VCAT circusits can be created over server trails in the following ways:
•
Manual routing
•
Automatic routing
–
Diverse routing: This method enables VCAT circuit routing over diverse server trail links.
Note
When creating circuits or VCATs, you can choose a server trail link during manual circuit routing. CTC
may also route circuits over server trail links during automatic routing. VCAT common-fiber automatic
routing is not supported.
For a detailed procedure on how to route a VCAT circuit over a server trail, refer “Chapter 6, Create
Circuits and VT Tunnels, Section NTP-A264, Create an Automatically Routed VCAT Circuit and
Section NTP-A265, Create a Manually Routed VCAT Circuit” in the
Cisco ONS 15454 Procedure
Guide
.
7.16.2.1 Shared Resource Link Group
The Shared Resource Link Group (SRLG) attribute can be assigned to a server trail link using a
commonly shared resource such as port, fiber or span. For example, if two server trail links are routed
over the same fiber, an SRLG attribute can be assigned to these links. SRLG is used by Cisco Transport
Manager (CTM) to specify link diversity. If you create multiple server trails from one port, you can
assign the same SRLG value to all the links to indicate that they originate from the same port.
7.17 Traffic Routing over a Third-Party Network
If ONS 15600 SDHs are connected to a third-party network, you can create an open-ended SNCP circuit
to route a circuit through it. To do this, you create three circuits. One circuit is created on the source
ONS 15600 SDH network. This circuit has one source and two destinations, one at each
ONS 15600 SDH that is connected to the third-party network. The second circuit is created on the
third-party network so that the circuit travels across the network on two paths to the ONS 15600 SDHs.
That circuit routes the two circuit signals across the network to ONS 15600 SDHs that are connected to
the network on other side. At the destination node network, the third circuit is created with two sources,
one at each node connected to the third-party network. A selector at the destination node chooses
between the two signals that arrive at the node, similar to a regular SNCP circuit.
