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Cisco ONS 15310-MA SDH Reference Manual, Release 9.1 and Release 9.2
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Chapter 7 Circuits and Tunnels
VC-12 Bandwidth
Right-click a node, port, or span on the detailed circuit map to initiate certain circuit actions:
• Right-click a unidirectional circuit destination node to add a drop to the circuit.
• Right-click a port containing a path-trace-capable card to initiate the path trace.
• Right-click a linear multiplex section protection span to change the state of the path selectors in the
linear multiplex section protection circuit.
7.3 VC-12 Bandwidth
The 15310E-CTX-K9 in the ONS 15310-MA SDH performs port-to-port time-division multiplexing
(TDM). The VC low-order path matrix for the 15310E-CTX-K9 has 96 logical VC high-order path ports.
All VC-12 multiplexing is achieved through these logical VC high-order path ports. Although the
15310E-CTX-K9 can support up to 2016 VC-12 cross-connects and 1344 bidirectional VC low-order
path circuits, the maximum number of VC12s that can be provisioned for Software Release 9.1 and 9.2
is 2016 VC 12 low-order path cross-connects and 1008 bidirectional VC12 low-order path circuits.
To view VC low-order path matrix resource usage, use the Maintenance > Cross-connect > Resource
Usage subtabs.
7.4 VC Low-order Path Tunnels and Aggregation Points
To maximize VC-12 cross-connect resources, you can tunnel VC-12 circuits through ONS 15310-MA
SDH nodes. VC-12 tunnels do not use VC low-order path matrix capacity at pass-through nodes, thereby
freeing the cross-connect resources for other VC-12 circuits.
VC low-order path aggregation points (VAPs) allow you to provision circuits from multiple VC-12
sources to a single VC high-order path destination. Like circuits, a LAP has a source and a destination.
The source is the VC high-order path grooming end, the node where the VC-12 circuits are aggregated
into a single VC high-order path. The LAP VC high-order path must be an STMn port. VC low-order
path matrix resources are not used on the LAP source node, which is the key advantage of VAPs. The
LAP destination is the node where the VC-12 circuits originate. Circuits can originate on any ONS
15310-MA SDH card or port.
7.5 DCC Tunnels
Each SDH frame provides four DCCs for network element (NE) Operations, Administration,
Maintenance, and Provisioning (OAM&P): one on the SDH Section layer (DCC1) and three on the SDH
Line layer (DCC2, DCC3, DCC4). The ONS 15310-MA SDH use the Section DCC (RS-DCC) or Line
DCC (MS-DCC) for management and provisioning. When multiple DCC channels exist between two
neighboring nodes, the ONS 15310-MA SDH balances traffic over the existing DCC channels using a
load-balancing algorithm. This algorithm chooses a DCC for packet transport by considering packet size
and DCC utilization. You can tunnel third-party SDH equipment across ONS 15310-MA SDH networks
using one of two tunneling methods, a traditional DCC tunnel or an IP-encapsulated tunnel.