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Site-to-Site VPn and MPLS Failover.


So, I'm fairly new to all of this.  But I'm looking to introduce an outside internet connection to each of our sites.  What I would like to do, is set up site to site VPNs as standard communications, and have our MPLS backbone be a failover route.

What we have is a four site topology.  Site A is our main datacenter.  It contains a 5510 Sec plus appliance.  We have MPLS provided to us, with an outside internet drain as well.  Sites, B, C, and D, are currently routed to site A via MPLS.  All traffice travels throughSite A for Internet.

What I'd like to do is place 5505's at B, C, and D.  I would like to create IPSec VPN tunnels to protect the networks. Using IP SLA's, I would like to test the connection, and remove the route if it fails(I've done this before, so I'm okay on that).  What I have a question on, is how do I set up routing for the networks?

The site to site VPN would try and send it out the VPN connection, no?    And if so, how do I change the routes on the 5510?  Currently, I have static routes pointing to the MPLS router for Sites B, C, and D.  Are those going to mess with the VPN connections?

4 Replies 4

Devavrat Oka

I am implementing a similar design. Was yours successful? Could you share some ideas? Thanks.


     It was, to an extent.  What I learned was that I can use TCP-State-Bypass to use the ASA to do some asynchronous routing, thought it may not be the best use.  What I did was set up the ASA as the default gateway, and configured SLA's on the ASA to monitor link state.  WHen that link failed to the internet, I had the ASA divert traffic to the MPLS provider router.

     State bypass come in to play because the ASA does not get to see the TCP packets increment sequentially.  Basically, when traffic comes out the MPLS provider router, it goes straight to the client, and the ASA doesn't get to see the full flow.

     State Bypass just tells the ASA to ignore TCP states for whatever policy you create(class-maps to policy-maps, etc.)

     I didn't much like this idea however, and after validating that it worked, embarked on changing the structure to be a bit different.  I plugged the internet into the ASA as normal, but I also created another interface that connected to the MPLS provider router.  This way, the provider was not local to our LAN, but I could bypass(no pun intended) using the TCP-State-Bypass command.  So my LAN sits behond my ASA, and I have a seperate interface for MPLS and Internet.

     Since my employer doesn't like to spend money, that's where i sit right now.  I believe a much better solution would have been to purchase a router, and set that as the default gateway.  Then I could have done routing on a router, and left the ASA to do its' job, to be a firewall.

Thanks Arvinder.

I am going to use DMVPN in my design. MPLS would be preferred and in case of failure traffic will be diverted over the DMVPN hub-spoke tunnels. Hope it works.

I didn't know about TCP-State-Bypass. Thanks for sharing that.

Hi Guys,

I know this is post is kind of old. But  I am implementing something very similar and would like to know how it was implemented highlighting configuration details.


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