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Cisco ONS 15454 Reference Manual, R7.0
78-17191-01
Chapter 11 Circuits and Tunnels
11.12 11.12 Section and Path Trace
When using a VT circuit on a VT tunnel (VTT), the VTT allows multiple VT circuits to be passed
through on a single STS without consuming VT matrix resources on the cross-connect card. Both
endpoints of the VTT are the source and destination nodes for the VTT. The node carrying VT circuits
through a VTT is called a VT-access node. In case of a source and destination node failure of the VTT,
the switching node performs 100-ms STS-level squelching for the VTT STS. The node dropping VT
traffic performs VT-level squelching. VT traffic on the VTT that is not coming from the failed node is
protected.
When using a VT circuit on a VT aggregation point (VAP), the VAP allows multiple VT circuits to be
aggregated into a single STS without consuming VT matrix resources on the cross-connect card. The
source for each VAP STS timeslot is the STS-grooming end where VT1.5 circuits are aggregated into a
single STS. The destination for each VAP STS is the VT-grooming end where VT1.5 circuits originated.
The source node for each VT circuit on a VAP is the STS-grooming end where the VT1.5 circuits are
aggregated into a single STS. The STS grooming node is not a VT-access node. The non VT-access node
performs STS-level squelching for each STS timeslot at the switching node in case the VT-grooming
node fails. The node dropping VT traffic performs VT-level squelching for each VT timeslot in case the
STS-grooming end node fails. No VT traffic on the VAP is protected during a failure of the
STS-grooming node or the VT-grooming node.
To view the VT squelch table, double-click the VT with a check mark in the BLSR STS squelch table
window. The check mark appears on every VT-access STS; however, the VT-squelch table appears only
by double-clicking the check mark on the node dropping the VT. The intermediate node of the VT does
not maintain the VT-squelch table.
The VT squelch table provides the following information:
• VT Number—Shows the BLSR VT numbers. The VT number includes VT group number and VT
number in group (VT group 2 and channel 1 are displayed as 2-1.)
• West Source—If traffic is received by the node on its west span, the BLSR node ID of the source
appears. (To view the BLSR node IDs for all nodes in the ring, click the Ring Map button.)
• East Source—If traffic is received by the node on its east span, the BLSR node ID of the source
appears.
11.12 Section and Path Trace
SONET J0 section and J1 and J2 path trace are repeated, fixed-length strings composed of 16 or 64
consecutive bytes. You can use the strings to monitor interruptions or changes to circuit traffic.
The OC192-XFP and MRC-12 cards support J0 section trace. Table 11-9 shows the ONS 15454 cards
that support J1 path trace. DS-1 and DS-3 cards can transmit and receive the J1 field, while the EC-1,
OC-3, OC-48 AS, and OC-192 can only receive the J1 bytes. Cards that are not listed in the table do not
support the J1 byte. The DS3XM-12 card supports J2 path trace for VT circuits.