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Community Member

vlan trunk across isp network

Hello,

I'm trying to create a trunk across a link that my isp has given to me. I have a 3550 at both ends and I need to move across a couple of vlans.

I have tried this config and the trunk comes up, but I cannot transfer any ip information across it.

This is configured on both ends:

interface FastEthernet0/1

switchport access vlan 509

switchport trunk encapsulation dot1q

switchport trunk native vlan 509

switchport trunk allowed vlan 509

switchport mode trunk

end

Do I need to create a tunnel or something first?

Thanks,

Dan.

8 REPLIES
Hall of Fame Super Bronze

Re: vlan trunk across isp network

Do you have a SVI for VLAN 509 at each switch ?

If so, let's see the show ip int brief from each switch as well as show vlan and show trunk

Community Member

Re: vlan trunk across isp network

switch1#sh ip interface brief

Interface IP-Address OK? Method Status Prot

Vlan509 10.50.9.24 YES manual up up

FastEthernet0/8 unassigned YES unset up up

switch2#sh ip interface brief

Interface IP-Address OK? Method Status Prot

Vlan509 10.50.9.3 YES manual up up

FastEthernet0/2 unassigned YES unset up up

switch1#sh interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/8 on 802.1q trunking 509

Port Vlans allowed on trunk

Fa0/8 509

Port Vlans allowed and active in management domain

Fa0/8 509

Port Vlans in spanning tree forwarding state and not pruned

Fa0/8 509

switch2#sh interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/2 on 802.1q trunking 509

Port Vlans allowed on trunk

Fa0/2 509

Port Vlans allowed and active in management domain

Fa0/2 509

Port Vlans in spanning tree forwarding state and not pruned

Fa0/2 509

The vlan exists on both switches when i type sh vlan

I have other trunk's setup on these switches to other locations on my own network. The only one that cannot transfer any traffic is the one over the isp link.

Re: vlan trunk across isp network

Hall of Fame Super Bronze

Re: vlan trunk across isp network

I'm assuming you are unable to ping from site A to site B ?

Community Member

Re: vlan trunk across isp network

That is correct.

Hall of Fame Super Bronze

Re: vlan trunk across isp network

Did you verify with the ISP that 509 is the transit VLAN ?

Did you try creating an additional VLAN (say, 510) and make that the L3 VLAN (of course, you will have to allow that VLAN in the trunk as well).

Community Member

Re: vlan trunk across isp network

Unfortunately I cannot rely on the isp in this situation. Is there a way I can create a tunnel or something of that sort?

Hall of Fame Super Bronze

Re: vlan trunk across isp network

The ISP supplies the end-to-end connectivity here. If their L2 configuration is not done correctly, you won't be able to establish a L2 or L3 connection between these locations.

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