Cisco 4431 sub-interface trunk to Catalyst 3660

[bruce.thornton]

This should be so easy, I've done it before.. Now I'm stuck. Trying to connect cat-3560 to 4431 vial sub-interface trunk.

The trunk will come online, however vlans will not pass across the trunk.

Router configuration:

interface GigabitEthernet0/0/2
 no ip address
 negotiation auto
 ip virtual-reassembly

interface GigabitEthernet0/0/2.912
 description Management NETWORK
 encapsulation dot1Q 912 native
 ip address 10.9.12.1 255.255.255.0
 ip helper-address 10.11.56.210

There are two more SVIs, if I can get on to span, sure others will work:

Switch configuration:

interface GigabitEthernet1/1/1
 switchport trunk native vlan 912
 switchport mode trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi1/1/1     on               802.1q         trunking      912

Port        Vlans allowed on trunk
Gi1/1/1     1-4094

Port        Vlans allowed and active in management domain
Gi1/1/1     1

Port        Vlans in spanning tree forwarding state and not pruned
Gi1/1/1     1

The router is server and switch is client. I have checked the the domain names match and the pass words match.  If I make the switch Transparent, it all works.

Any help would be appreciated.

[Mark Ruhland]

Try taking the "native" off the dot1q line.  The native vlan is untagged and I would think you want all your traffic to be tagged.

nterface GigabitEthernet0/0/2.912
description Management NETWORK
encapsulation dot1Q 912 native
ip address 10.9.12.1 255.255.255.0
ip helper-address 10.11.56.210

[Cristian Matei]

Hi,

   Based on the configuration provided for Gig1/1/1 and the output of "show interfaces trunk", it looks like the VLAN's have not been created; only VLAN 1, the default 1 exists in the switch database.

Regards,

Cristian Matei.