Layer2 over Layer3

Paul Vinciguerra pvinci at VinciConsulting.com
Fri Sep 14 22:08:29 UTC 2012


Philip,

Here is the best reference I know of to address your issue.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper_c11_493718.html#wp9000281



From: Philip Lavine [mailto:source_route at yahoo.com]
Sent: Friday, September 14, 2012 6:06 PM
To: David Swafford; Paul Vinciguerra
Cc: NANOG list
Subject: Re: Layer2 over Layer3

If the psuedowire is setup to allow a vlan to be exteneded, but the vlan is already extended over a dedicated link, how will spanning tree behave? Right now I have it setup and I dont see the psuedowire trunk in a blocking state. Will the switch that has both the pseudowire trunk on it and the dedicated link know how to forward the frames if either goes away?


From: David Swafford <david at davidswafford.com<mailto:david at davidswafford.com>>
To: Paul Vinciguerra <pvinci at vinciconsulting.com<mailto:pvinci at vinciconsulting.com>>
Cc: Philip Lavine <source_route at yahoo.com<mailto:source_route at yahoo.com>>; NANOG list <nanog at nanog.org<mailto:nanog at nanog.org>>
Sent: Wednesday, September 12, 2012 7:46 PM
Subject: Re: Layer2 over Layer3

Hey Philip,

Any Transport over MPLS will do this too.  Here's a link to an example
setup of two sites where just L3 connectivity exists between them:
https://w.ntwk.cc/working-on-atompls/.  In that setup, I have just
IPSEC VPN connecting the two locations, but have an 802.1q trunk
extended between both.  In the example configs, Fa0/1 on both ends is
a transparent L2 connection.  The boxes used here were 3725s on 12.4T.

David.




On Wed, Sep 12, 2012 at 3:37 PM, Paul Vinciguerra
<pvinci at vinciconsulting.com<mailto:pvinci at vinciconsulting.com>> wrote:
> ASR supports OTV if you can do multicast over L3.  Although, you may not need L2 extensions in the end.
>
> -----Original Message-----
> From: Philip Lavine [mailto:source_route at yahoo.com<mailto:source_route at yahoo.com>]
> Sent: Wednesday, September 12, 2012 6:23 PM
> To: NANOG list
> Subject: Layer2 over Layer3
>
> To all,
>
> I am trying to extend a layer2 connection over Layer 3 so I can have redundant Layer connectivity between my HQ and colo site. The reason I need this is so I can give the "appeareance" that there is one gateway and that both data centers can share the same Layer3 subnet (which I am announcing via BGP to 2 different vendors).
>
> I have 2 ASR's. Will EoMPLS work or is there another option?
>
> Philip
>



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