How to do L2TPv3 redundancy

[Tod Larson]

We have 2 data centers at different sites.  We have 2 WAN connections and 2 WAN routers on each end for redundancy.  We currently have 1 router at each end configured with a L2TPv3 tunnel extending a vlan104 across the 2 sites.

What is the recommended way to add a L2TPv3 tunnel to my redundant routers?

I'm cautious to simply pin up another L2 tunnel since I'm thinking spanning tree won't like having two L2 connections across the WAN.

Thank you,

[narainarun]

Hi,

I think you can extend the same VLAN to your redundant routers and tweak with STP parameters to make one router/link primary and the other secondary.

If your network is MPLS enabled then you can look for enabling ATOM L2VPN as there is a feature called "Pseudowire redundancy" which would be ideal for your requirement. Pseudowire reundancy is not applicable for L2TPv3 based VPNs.

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/fspseudo.html

HTH

Arun

[Giuseppe Larosa]

Hello Tod,

I agree with Arun:

you can use a second L2TPv3 tunnel if you tune STP parameters on the switch ports connected to this second pseudowire.

You can increase STP cost per vlan or link based and you can build a backup path in this way.

Depending on the platforms you are using EoMPLS can be a more efficient way to do this job, or it can be an unsupported option

Hope to help

Giuseppe

[Tod Larson]

Can anyone point me to a good document on tweaking STP parameters?

Thank you.

[narainarun · Accepted solution]

Hi,

You can manipulate the port cost under the interfaces in switch with

interface fax/x

spanning-tree vlan cost - For Specific VLAN (or)

spanning-tree - For all VLANs

This way the port with higher cost become secondary and with lower one become primary.

You can refer to the document which explains basic STP configuration and understanding.

http://www.networkers-online.com/blog/2008/07/how-to-configure-spanning-tree-protocol-part3/

http://www.cisco.com/image/gif/paws/10556/spanning_tree1.swf

HTH

Arun

[Edison Ortiz]

As indicated, there are some features on EoMPLS that aren't available on L2TPv3 with that said, you have not tell us the bandwidth available on those WAN links. If they are Gig links, you simply do nothing. Just connect the switches to the two L2TPv3 enabled interfaces and STP will provide you with a loop free topology.

We don't manipulate the cost on a datacenter interswitch links, I don't see the need to do so on this case - unless you want to force one link over the other.