Issue Connecting Cisco Catalyst Express 500 with Nortel 8610 using 802.1Q

[IWilson8]

Has anyone come across this problem before.

We have just bought some Cisco Cataylst Express 500s and have applied the router role using the smart ports to the uplink port.

When we connect Cisco to Cisco this works fine, but when we connect to the Nortel we get an STP error "802.1Q packet recived on a non trunk port"

This normally results in STP blocking a unrelated port on the Nortel. We have checked the Nortels port setting and they are identical to other uplink ports.

Any Ideas?

[ebreniz · Accepted solution]

If I understand your problem correctly you are having problems connecting your 500 switch to a Nortel Switch. From the

information that you have provided I can see that there are two problems with your configuration.

a) The switch port on Cisco is configured as an access port but the port on Nortel is configured as a trunk port. BPDUGuard is on by default on access ports that is why the port went into inconsistent port type. 802.1Q is a trunk port protocol (can not be enabled on an access port).

b) Also there is a native VLAN mismatch in the configuration. From what you have told me the Nortel Switch is on VLAN 926 and the Cisco is on VLAN 226. For 802.1Q to work corrctly the native VLANS need to be identical.

To solve this problem you will need to change the native VLAN for the cisco switch port GigabitEthernet0/1 to 926 (the same as Nortel switch port that is connected) and change the port type to trunk.

The commands for configuring trunk are as follows

switch# config t

switch# int gig0/1

switch# switchport access vlan 926 /* optional*/

switch# switchport trunk native vlan 926

switch# switchport trunk encapsulation dot1q

switch# switchport mode trunk