MX's connected via MPLS sharing internet

[PeteShack]

We've got two sites connected with MXs via MPLS (AT&T AVPN).

This allows us to easily access resources between sites.

MPLS routers are connect to MX's LAN ports.

Both sites have internet connected to MX's WAN port.

Sites have separate subnet addresses, and MX has static routes.

I would like site B to be able to use site A's internet service if site B's local internet fails.

I'm OK with manually switching it over.

My guess is I would need to:

• Get AT&T to allow ALL traffic through their routers, across the MPLS (instead of just the few VLANS they have configured now)
• And, I would have to create a static routes in both MX's to allow ALL subnets through.

Does this sound correct?  Am I missing anything else?

[MilesMeraki]

In theory, your assumptions are correct. I'd be interested to see if the static routes work as they may take precedence over the default WAN routes which allows traffic to pass onto the Internet at both sites.

What do you have connected down-stream from the MX's? Any layer 3 switches? 

[PeteShack]

Thanks.  Yeah I guess I'll try and see what happens.

Yes, we Meraki MS350-48's L3 switches at both sites, but they're not configured to do any routing now.   How would they help?

[MilesMeraki]

Give it a go and tell me how you get on. - I was trying to see whether it would be capable of using dynamic routing, effectively if the MX failed then all traffic could be re-routed to the secondary site. The only thing I just remembered that the MX can't actually do LAN dynamic routing at this moment in time.