From: Stemberger, Gregory J [NTK] (greg.x.stemberger@sprint.com)
Date: Fri Oct 14 2005 - 19:24:41 GMT-3
I have also delt with a similar scenario in which the customer had backdoor links at all of their locations (redundant network with OSPF) and potientally required a full mesh of sham links. The sham links were not fully supported yet by the provider yet and we were concerned about the future necessity to have them in a full mesh setup. So, in a effort to continue the migration from their legacy network to an L3MPLS network and maintain full mesh connectivity, we decided to deployed Multipoint GRE with NHRP (no IPsec/DMVPN) overlaid on the MPLS network. This allowed us to maintain the routing control and the existing OSPF routing functionality between CE devices from their legacy network. We needed the routes to remain intra-area because of the backdoor links. Secondly, reducing the complexity on the CE devices wasn't really a concern for this network because all of the routers were managed. The solution has been flawless for this customer up to this point. The Tunnel!
s build and tear down without much overhead on the routers because, in this case we are not running any IPsec and the routers only need to maintain the NHRP tables. Secondly, just as with a typical DMVPN solution, when using spoke to spoke connectivity, we also have control plane scalability from a routing standpoint because a routing adjacency is only built between the NHRP Server/Hub and the spokes. All spoke to spoke traffic runs direct by using NHRP and resolving the NBMA address for the tunnel endpoint.
-Greg
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of simon hart
Sent: Wednesday, October 12, 2005 4:54 PM
To: Scott Morris; 'Andrew Lissitz (alissitz)'; 'C&S GroupStudy'; 'Cisco certification'
Subject: RE: OSPF Sham Links
When I worked at Colt Communications we used this as part of our MPLS
deployment. It was when clients had a backdoor route to a network but
wished to use the MPLS network as preference
Simon
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Scott
Morris
Sent: 12 October 2005 15:05
To: 'Andrew Lissitz (alissitz)'; 'C&S GroupStudy'; 'Cisco certification'
Subject: RE: OSPF Sham Links
It's a pretty festive little feature although so far I've only used it in a
lab just to see how it really works. :)
I'd be interested to hear as well about people experience with it in
production in case anyone's trying OSPF over the L3VPNs.
Cheers,
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Andrew Lissitz (alissitz)
Sent: Wednesday, October 12, 2005 9:29 AM
To: C&S GroupStudy; Cisco certification
Subject: OT: OSPF Sham Links
Hello group,
Out of curiousness, has anyone deployed this? OSPF Sham Links ... Any
thoughts? Are any ISPs or enterprises using this? Did it solve the problem
of OSPF route preference process? Here is a link in case anyone wants to
learn more about it.
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_
chapter09186a00804556e9.html
Any one?, any one? (you have to read this with the same voice used in the
movie Ferris bueller's day off)
Thanks group,
Andrew
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