[c-nsp] Layer Two tunneling question (advice needed)

[Lamar Owen]

On Monday, January 03, 2011 07:23:27 pm John Neiberger wrote:
> So, I think some sort of layer two tunneling is in order. What are our
> options if we want to make DeviceA and DeviceB think they're local to
> each other and in the same LAN? I've heard of L2TP and of various MPLS
> techniques that might solve this, but I've just never needed to use
> them and really know nothing about how they're configured or if
> they're even legitimate options.

At one point in time I had a similar need between two sites that were connected via a PoS OC3; I had two Catalyst 550x's (not 6500, but 5500 series; one a 5509 and one a 5505) with Sup3Gs and RSFCs available.  I used the marginally documented 'bridged GRE' technique, since the RSFC doesn't do L2TPv3 either.  Not sure if bridged GRE tunnels work with 6500 gear.  But I successfully used the bridged GRE tunnel for a couple of years until the need for layer 2 transparency between the sites went away.  I don't remember offhand the configure commands used..... but a quick search and I found http://www.net-gyver.com/?p=952

Note that that is not a supported feature, and IOS tells you so when you configure it.  If nothing else it could be a stopgap while you figure out the permanent solution.

What sort of linecard(s) are these routed interfaces on?  I know that some linecards support features other linecards do not, and, in particular, if you're using old OSM GE WAN cards the GE-WAN interfaces can't do L2 features, but can do some MPLS things.