Troubleshooting guide

E-6
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Appendix
Architecture Problems
Note For information about Buffer Tuning see the following URL:
http://www.cisco.com/warp/public/63/buffertuning.html
Step 8 Enter the hold-queue interface configuration command to double the interface hold queue values.
Switch(config)# interface gigabitEthernet 1/0/0
Switch(config-if)# hold-queue 150 in
Switch(config-if)# hold-queue 80 out
Step 9 On the connected Ethernet switches, disable any inactive spanning tree sessions not actively being used.
Step 10 Verify that spanning tree is functioning and enabled on all connected Ethernet switches, and VLANs.
Step 11 Review the need for the Backbone fast feature on any Catalyst Ethernet switches, and verify this feature
is needed in the network.
Step 12 Enter the show buffers command to verify the number of available buffers and the number of “misses”.
Step 13 If you run out of buffers, use the buffers configuration commands to increase the number of buffers for
one or more of the buffer pools.
NO HARDWARE RESOURCE Error During VC Configuration
When configuring an ATM VC on the ATM switch router, you might see the following error during
configuration:
Switch(config)# interface atm 8/0/0
Switch(config-if)# atm pvc 21 1837 interface atm 1/0/0 1 68
%connection creation fails: connection installation failure
%connection deletion fails:specified connection is not a pvc or pvp
This failure is caused by fragmentation of the ITT (input translation table) memory. This memory is used
to manage the input of cells into the switch.
Note Cisco IOS Release 12.1(7a)EY fixes this problem, and you might only need to upgrade the IOS image
on your switch. If you are not using Cisco IOS Release 12.1(7a)EY “or later” on the
Catalyst 8540 MSR, there are 32K of ITT entries available for each of the 8 MSC modules, instead
of 128K for each MSC module. On the LightStream 1010 ATM switch, there are 2 banks of 32K of
ITT entries available, instead of the 2 banks of 64K available.
To verify the “connection installation failure” is caused by the “NO HARDWARE RESOURCE” error
enter the show atm vc interface command on the interface with the failure.
Switch# show atm vc interfaces atm 8/0/0
Interface VPI VCI Type X-Interface X-VPI X-VCI Encap Status
ATM8/0/0 96 36 PVC ATM2/0/0 1 2032 NO HW RESOURCE
Check the Status column. If “NO HARDWARE RESOURCE” appears, this is a failure of the ITT
memory to free up blocks of memory for VCI numbers.
You can also use the debug atm conn errors and events commands to monitor ATM connection errors
and events as they are generated after configuring a VC.
Switch# debug atm conn errors
ATM Connection Management error debugging is on
Switch# debug atm conn events
ATM Connection Management event debugging is on