Hi,
Using dynamic protocolls with two MPLS VPN providers interconnecting the same sites CAN lead to routing loops if not designed carefully together with both SPs.
Mainly what could happen: a network from site A is announced through SP1 to site B, which announces it back to site A through SP2, which in turn announces it back to site B ... etc.
The PE-CE protocolls have different capabilities to handle this scenario. Also of interest might be to choose one path as primary and one as backup. From the point of your SP you are installing a backdoor link between sites. If you are interested in EIGRP, have a look at "MPLS VPN Support for EIGRP Between Provider Edge and Customer Edge "
http://www.cisco.com/en/US/docs/ios/12_4/ip_route/configuration/guide/h_eipece_ps6350_TSD_Products_Configuration_Guide_Chapter.html
and "BGP Cost Community Support for EIGRP MPLS VPN PE-CE with Backdoor Links"
http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fsbgpcce.html
From the later document you can understand that the MPLS VPN provider likely needs to change the PE configuration, as you redesign your IP routing. You need to talk to both SPs to get their statement regarding what is possible and what is not. Note: there might be a big difference between what is technically possible and what is offered as a product by a SP.
What will always work: use floating static routes towards the backup MPLS VPN and dynamic routing with your primary MPLS VPN.
A clean hierarchical IP address design will simplify this setup a lot.
Hope this helps! Please use the rating system.
Regards, Martin
