Routing Traffic through site to site VPN

[Michael McGrath]

Attached is a diagram of my setup. I have 3 sites each connected to each other with a site to site VPN. I'm looking for advice and a solution if one of the legs of the VPN were to go down.

For example if the connection between SiteA and SiteC were to go down, is there a way that SiteA and SiteC can still communicate through SiteB?

[Georg Pauwen]

Hello,

a full mesh DMPVPN would be an option, as described in the document below:

http://www.cisco.com/en/US/technologies/tk583/tk372/technologies_white_paper0900aecd801af458.html

[Michael McGrath]

Would a DMPVPN work with ASAs? two of the gateways are 5512 and the other is a 5505

[pankajbhosale]

Hi,

Assuming you have two physical links on all of your routers.

Example

Router A has two links

Link 1 connecting to router B

Link 2 connecting to router C

You can configure router  A to access router B & router C in scenario where one of your link is down.

How to do this?

Link 1 will have two tunnels configured, tunnel 1 connecting to router B and tunnel 2 connecting router C.

Link2 will have two tunnels configured in the same way you configured for link 1.

In the end make sure router A has routes for networks connected to router B & router C

Bye

[Joseph W. Doherty]

For example if the connection between SiteA and SiteC were to go down, is there a way that SiteA and SiteC can still communicate through SiteB?

Sure can but it depends on routing being properly configured.

For example, if you were running a dynamic routing protocol, it should reconverge after the SiteA<>SiteC path is lost and communicate that SiteA and SiteC can reach each other via SiteB.

[Michael McGrath]

I didn't know I could use dynamic routing for this setup, thanks.

every site's gateway is an ASA with a nat rule like this 

nat (any,outside) source static SiteA_Networks SiteA_Networks destination static SiteC_Networks SiteC_Networks no-proxy-arp route-lookup

I'm unsure of how the NAT will look with a protocol like OSPF, for example. I'm still looking into it, but any advice or articles would go a long way

Thank you