System information

Troubleshooting ATM Switching Environments

Book Title

21-448

Not enough bandwidth Step 1 If there is not enough bandwidth available to support the virtual circuit, the

circuit cannot be created. Check the cells available attribute to determine how

much bandwidth is available (that is, how much has not been allocated to other

virtual circuits). Use the show port c.p all command to display all port attributes

(name, status, statistics, physical, frameforward, framerelay, DLCI, VCI,

PVC, VPI). This is the default, with show port c.p followed by no arguments.

Step 2 Check the cells required attribute to see how many cells of bandwidth are

needed to carry the virtual circuit over a trunk. Use the show port c.p vci VCI#

command to display, for the speciﬁed ATM UNI port, the following attributes of

the PVC with the speciﬁed VCI:

• 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

Trunk down Make sure that any trunks in the path between the endpoints are active. For more

information, see the section “ATM Switching: Trunk Does Not Come Up” earlier in this

chapter.

1 PVC = permanent virtual circuit

2 VCI = virtual channel identifier

3 CLC = cell line card

Possible Problem Solution