Question on extending VLAN over GRE tunnel

[Yang Xia]

Dear NetPros,

Since GRE is a layer3 technology would it be possible to use it to extend a vlan from one location to the other side of the tunnel which is in a separate geo location? I'm not interested in using L2TPv3 because it doesn't support 6500 platform.

Thanks in advance!

[Richard Burts]

Yang

Extending the VLAN over a GRE tunnel would require bridging the VLAN and carrying the bridged traffic over the GRE tunnel. This is not a supported implementation.

You can enter the configuration commands and they are accepted (they are not an error - at least not the last time I tested it). I have heard people say that they have configured this and that it passed traffic. However Cisco does not support it. If you try it and something unusual happens Cisco will not help you fix it.

HTH

Rick

[Yang Xia]

Thanks Rick for your replying. Do you mean using the vlan bridge group over GRE tunnel? I haven't seen any document in CCO and won't be surprised that is not supported feature by Cisco.

[AlexFer]

---

@Richard Burts wrote:

Extending the VLAN over a GRE tunnel would require bridging the VLAN and carrying the bridged traffic over the GRE tunnel. This is not a supported implementation.

Is this exactly what Cisco supports using "Layer 2 over Multipoint GRE (L2omGRE)", albeit in more robust functionality?

[Richard Burts]

It is interesting that you have found this old discussion to revive. The original post asked about extending a vlan to another site using GRE. My suggestion was that to extend a vlan over GRE might work if they used bridging on the GRE tunnel interface but while this might work that it was not a supported implementation. I believe that my statement is still technically true. But it appears that you have found a different approach (using xconnect rather than bridging) and that approach does appear to do exactly what the original poster wanted. So a well deserved +5 for finding a solution for the original question. 

[Giuseppe Larosa]

Hello Yang,

if you cannot use L2TPv3 could EoMPLS be a viable option ?

You can ask your provider for EoMPLS services.

In a MAN context just Q in Q tunneling is a good solution (double 802.1Q tagging).

Look for metro ethernet solutions on the CCO

Hope to help

Giuseppe

[Yang Xia]

Hi Giuseppe,

QinQ should work but I don't have the layer2 service from my ISP, only BGP peering.

I checked CCO and found the EoMPLS for 7600. I'll check it out and see how it can be used at all.

http://www.cisco.com/en/US/docs/ios/12_1/12_1e8/feature/guide/tryvlan.html

Thanks!

[lamav]

Yang:

Is using VPLS (layer 2 VPN) solution an option for you?

Victor

[Yang Xia]

Hi Victor,

Thanks very much for replying.

My situation is I have a single network to be extended to the data center where the VM cluster locates. I doubt layer2 VPN will work in this scenario. But I'll keep it in mind.

Regards,

Yang

[lamav]

Yang:

When i asked if you think this could be a solution for you, I was talking more in terms of cost, planning, authorization and approval from your management, etc.

I wasnt questioning the technical feasibility. A layer 2 VPN is meant to do exactly what youre talking about: extend a layer 2 domain/vlan across the public network over an MPLS cloud.

HTH

Victor

[Yang Xia]

To use the VPN MPLS technology, ISP has at least to setup their own MPLS cloud and assign RTs to the routes. This approach isn't just feasible for me at this time. Thanks for the thought. I was looking for a quick GRE related approach to extend the VLAN to the VM cluster.

Thanks,

Yang

[lamav]

So what youre saying is that your provider either doesnt provide MPLS as a service offering or your organization is not ready for that commitment.

Gotcha.

Good Luck.

Victor

[Yang Xia]

yes you're right Victor. My ISP isn't ready for full blown MPLS applications. In the mean time I need a quick solution without adding another circuit for the virtual servers to be on the same local vlan.

[Louey]

Hi Yang

Can you share your experience about this issue ?

Have you tried this or went with an l2vpn solution through MPLS ?

Kind regards