[c-nsp] GRE tunnel to do span vlan across two datacenters?

[David Prall]

Since GRE isn't supported on the 3750, it seems like a non-starter. While
you can configure GRE, it is all done in software thus impacting all control
plane traffic. As well bridging isn't supported over GRE. 

If you have Dark Fiber, I would recommend using it. 

David

--
http://dcp.dcptech.com


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Jason Gurtz
> Sent: Wednesday, July 06, 2011 12:09 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] GRE tunnel to do span vlan across two datacenters?
> 
> A firm has proposed creating a GRE tunnel between two datacenters
> (using a
> 3750X stack at each) to create the spanned vlans needed for VMWare
> failover application.
> 
> Clearly there is tunnel overhead but I sense there are other failure
> modes
> here that aren't so clear to me--I am familiar in concept with GRE
> tunnels
> but don't have a heck of a lot of opex. Can anyone share more insight
> on
> the merit (or lack of) with this proposed design? I am aware (via this
> list, thanks!) of several shortcomings surrounding 3750 based stacks,
> but
> cisco alternatives seem pricier still or too big. There is dark fiber
> available, what about VPLS w/ LDP or L2TP solution?
> 
> Current network is L3 at the access layer w/ OSPF (4507-sup6 access,
> 4900M
> cores):
> 
>      A1
>      /\
>    /    \
>  C1------C2
>    \    /
>      \/
>      A2
> 
> Maybe it is better to just overlay stp back on to the network w/root
> and
> alt-root at C1/C2 (V1 and V2 are the proposed 3750X stacks)? Scary to
> me,
> but an an argument can be made for less complexity -vs.- tunnling/vpn
> based approach.
> 
>      A1     .V1
>      /\ . ' /
>    /. ' \ /
>  C1------C2
>    \` . / \
>      \/ ' . \
>      A2     'V2
> 
> OTOH, by the time this actually gets done maybe TRILL will be out ;)
> Hopefully this enterprisy topic is not too OT!
> 
> ~JasonG
> 
> 
> 
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