Alcatel Carrier Internetworking Solutions 8800 User Manual

Troubleshooting 802.1Q

Troubleshooting 802.1Q

page 8-2

OmniSwitch Troubleshooting Guide

When troubleshooting an 802.1Q problem, it is important to not only investigate the 802.1Q feature and 
configuration, but also the basic Ethernet connectivity between the problematic switches. Please refer to 

 of this document.

If there is no traffic passing at all across an 802.1Q link, verify basic Ethernet connectivity.

If there are particular VLANs that are not able to pass traffic, verify the configuration on both sides of the 
link using the show vlan port CLI command. This will display the 802.1Q VLANs that are configured. It 
will also display the default untagged VLAN. Confirm that these are configured correctly.

-> show vlan port 1/24
vlan     type      status
--------+---------+--------------

1    default   forwarding

30    qtagged   forwarding
40    qtagged   forwarding
50    qtagged   forwarding

Verify the ports are in forwarding as expected. Note which bridge mode the switch is running in (1 per 
VLAN or 1 per switch) If spanning tree appears to not be working correctly, please see 

 of this document.

Note that different spanning tree protocols can be used on the same tagged port.

To verify which VLAN a specific flow is being classified into, use the show mac-address-table command 
shown below:

-> show mac-address-table 5/24

Legend: Mac Address: * = address not valid

Vlan      Mac Address          Type       Protocol    Operation    Interface

------+-------------------+--------------+-----------+------------+-----------

30   00:d0:95:88:67:ce     learned          10806     bridging      5/24
50   00:d0:95:88:67:d0     learned          10806     bridging      5/24

Total number of Valid MAC addresses above = 2

OmniSwitch 7800

OmniSwitch 7800