3. Troubleshooting Functional Failures in Operation383.5 Layer 2 Network Communication Failure3.5.1 Layer 2 Communication by VLAN Is DisabledIf layer 2 communication is disabled when using VLAN, isolate the problem using failure analysis method listed in thefollowing table.(1) Checking VLAN statusExecute the show vlan command or execute the show vlan command with "detail" parameter specified and checkthe VLAN status. Check items for each VLAN function are listed below.(a) Check items common to all VLAN functions• Confirm that the VLAN setting for the port is correct.• Confirm that the port has been set up with the compatible mode. If the expected port does not belong tothe default VLAN (VLAN ID 1), check the setting below.• Confirm that a port VLAN other than VLAN ID 1 is not assigned for the access VLAN or native VLAN.• Confirm that the default VLAN setting is assigned for "allowed vlan" in the trunk port.• Confirm that a mirror port is not assigned for.• Confirm that VLANs with the function enabled (such as VLAN authentication [static] of IEEE802.1Xfunction, Web authentication [fixed VLAN mode], and MAC authentication) and VLANs with the functiondisabled are not in the same trunk port.(b) Check items for protocol VLANIf protocol VLAN is in use, execute show vlan and confirm that the protocol is set correctly.# show vlan:VLAN ID:100 Type:Protocol based Status:UpProtocol VLAN Information Name:ipv4EtherType:0800,0806 LLC: Snap-EtherType:Learning:On Uplink-VLAN: Uplink-Block: Tag-Translation::(c) Check items for MAC VLAN• When using the MAC VLAN, execute the show vlan mac-vlan command to confirm that the MACaddress that is allowed the VLAN communication is set up correctly. The value in the parentheses indicatesthe function that registers a MAC address.[Function]static: MAC address that is set with configuration.dot1x: MAC address that is set with IEEE802.1X.wa: MAC address that is set with Web authentication.vaa: MAC address that is set with authentication VLAN.# show vlan mac-vlan:VLAN ID:100 MAC Counts:40012.e200.0001 (static) 0012.e200.00:02 (static)0012.e200.0003 (static) 0012.e200.00:04 (dot1x)• Execute the show vlan mac-vlan command to confirm that the same MAC address on the layer 2authentication has not been set up for different VLAN configuration. A MAC address with * (asterisk) means
