Troubleshooting guide

12-10
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 12 Troubleshooting Layer 2 Interfaces
Troubleshooting Layer 2 Switching
Refer to the Layer 3 Software Feature and Configuration Guide if any changes are necessary to the
configuration of the interface.
Other Layer 2 Switching Problems
This sections describes the following, less common, Layer 2 switching connection problems:
• Layer 2 Connection is Flooding, page 12-10
• Packets are Switched but are Not Appearing on the Wire, page 12-11
• Layer 2 CAM Display, page 12-11
• Check for Spanning Tree Loop, page 12-11
Layer 2 Connection is Flooding
If you determine the Layer 2 connection is flooding instead of switching, check the following:
• If the destination address of the traffic is known:
– Check the Layer 2 CAM of the ingress interface for the specific destination address. If the entry
exists, then note the destination interface number.
– Use the show epc ifmapping command and note the name-string of the interface.
– Display the interface table in the ingress interface for the destination interface (obtained from
the Layer 2 CAM).
– Get the BROUTE VC from the show epc if-entry interface command described earlier.
– Use the show atm vc traffic interface interface-namestring 0 BROUTE-VC command.
– Confirm that the “rx” and “tx” counters are increasing when traffic is switched (by entering the
previous command, waiting, and entering the same command again).
• If the destination address is unknown:
– Use the show epc patricia interface command to display the interface table in the ingress
interface for all the interfaces in the bridge-group.
– Get the BROUTE VCs from the show epc if-entry interface command described earlier, for all
the interfaces in the bridge group.
– Use the show atm vc traffic interface interface-namestring 0 BROUTE-VC command.
– Confirm that the “rx” and “tx” counters are increasing when traffic is switched (by entering the
previous command, waiting, and entering the same command again).