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Q in Q Trunking Configuration- On Catalyst switch with Trunks and VLAN Interfaces

gregwoodson
Level 1
Level 1

I have a router config at a client site where this is the relevant config

interface GigabitEthernet0/0.3005
encapsulation dot1Q 3005
ip address 10.250.0.34 255.255.255.252

!
interface GigabitEthernet0/0.3005998
encapsulation dot1Q 3005 second-dot1q 998
ip address 10.252.0.2 255.255.255.252
!
interface GigabitEthernet0/0.3005999
encapsulation dot1Q 3005 second-dot1q 999
ip vrf forwarding Public
ip address XX.XX.XX.142 255.255.255.252

When you are dealing with a 6509- where these circuits come into an NNI (Trunk with multiple VLANS)- and VLAN virtual interfaces-  how do you do the config on that side?

Thanks

Greg

5 Replies 5

Philip D'Ath
VIP Alumni
VIP Alumni

So you have already de-encapsulated it, so it will come in as an already tagged packet.

Did you want to terminate it as a layer 3 interface, or as a simpler layer 2 VLAN?

Bring in to an NNI- then doing virtual interfaces:

interface GigabitEthernet2/7
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1598-1600,3000,3002-3008,3010-3016,3018-3020
switchport mode trunk

interface Vlan3005
ip address 10.252.0.1 255.255.255.252
no ip redirects
no ip unreachables

Your config above looks perfect to me.  What isn't working?

Coming back the other way-  vlan 999 doesnt know to go back through vlan3005 to get to the other side (.141 cant see .142- but 10.250.0.33 can see 10.250.0.34 and vice versa):

interface GigabitEthernet3/1
switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 999,3005
switchport mode trunk

interface Vlan999
description guest wireless
ip address XX.XX.XX.141 255.255.255.252
!
interface Vlan3005
description Regular WAN
ip vrf forwarding Customer
ip address 10.250.0.33 255.255.255.252
!

I see.  I think what you want on your site is a dot1q tunnel, to tunnel all VLANs at the customer site, rather than just VLAN 3005.

Check out "switchport mode dot1q-tunnel".  I found this great example:

https://networklessons.com/switching/802-1q-tunneling-q-q-configuration-example/

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