System information

Troubleshooting ATM Switching Environments 21-447
ATM Switching: Virtual Circuit Fails to Be Created
Possible Problem Solution
Virtual circuit not
configured on both
endpoints
Step 1 Use the show port command to verify that the virtual circuit is configured on
both endpoints. The virtual circuit must be configured on both endpoints for the
circuit to be created.
Step 2 If one endpoint does not have the virtual circuit configured, reconfigure the
endpoint. For each virtual circuit you must specify the node, card, and port at
each end and the required bandwidth.
For detailed information on configuring virtual circuits, refer to the LightStream 2020
Configuration Guide.
Port in inactive mode
Step 1 Check to see whether the virtual circuit is configured on an inactive port. Use the
show port command to check the status of the port.
Step 2 If the port is in inactive or testing mode, bring the port up using the set port
port-number active command.
cardMaxVCs attribute
set too low
If the cardMaxVCs attribute is set too low on a line card, there might be insufficient
resources available for creating a virtual circuit. Increase the value of this attribute and
reboot the line card. The following switchwide attribute may be configured only in expert
mode in the configuration tool:
• Max VCs for this card—setsnmp cardMaxVCs.card# nnn
Bandwidth or other
circuit attributes
misconfigured
If the virtual circuit has illegal attributes set, the circuit will not be created. Review the
bandwidth values in particular. Use the following commands to review the settings:
• Use the show port c.p vci VCI# command to display, for the specified ATM UNI port,
the following attributes of the PVC
1
with the specified VCI
2
:
— Source node, port, and VCI
— Source insured rate, insured burst, maximum rate, and maximum burst (operational
and administrative)
— Destination operational node, port, VCI, insured rate, insured burst, maximum rate,
and maximum burst
— To-net and from-net circuit ID and circuit state, last error reported by ATM
management, and cells required
— Counts of cells to the switch with CLP= 0 or 1, a count of cells to the switch with
CLP = 0 upon arrival at the port, but forwarded with CLP = 1, and a count of
discarded cells
A virtual circuit cannot have a MaxRate larger than the port. Also, certain
combinations of parameters are illegal. If a virtual circuit uses guaranteed bandwidth, it
cannot have any excess bandwidth. The insured rate must equal the max rate.
• Use the set port c.p vci vci# insured-rate cells/sec command to set the insured rate to
cells/sec for the specified ATM UNI PVC. The insured rate is the upper bound on the
non-sharable bandwidth that the connection may use in a sustained way. The range is
0–100,000,000 bits per second. The default for ATM UNI circuits is 0 cells per second.
• Use the set port c.p vci vci# max-rate cells/sec command to set the maximum rate to
cells/sec for the specified ATM UNI PVC. The maximum rate is the upper bound on
the rate of all traffic (insured and noninsured) allowed to enter the LightStream 2020
network, congestion permitting. The default rate is the line rate for all cards except the
CLC
3
, for which the default rate is 218 cells/sec.
Refer to the LightStream 2020 Configuration Guide for more information.