Internet load balancing?

[louis0001]

We have an MPLS network with 50 sites that connect to 2 central sites (SITE A & B) that are about 100 miles apart (see diagram)

The 2 central sites (SITE A & B) are connected directly to each other via a 100mb link.

One Central site (SITE B) has an ASA which allows all traffic from our MPLS network to the internet.

What would happen if we added another ASA and internet connection at SITE A?

Which way would the traffic flow if the gateway of last resort at SITE A was set to a new ASA (at SITE A) with internet connection.

Would all traffic still go out of SITE B (the current internet connection) or would some go out of SITE A (new internet connection) and if it did this, what would determine what site (SITE A or SITE B) the other 50 sites on the MPLS network used to access the internet?

[Richard Bradfield]

At the moment what determines if traffic from branch sites goe to A or B? is B the main site and A the backup? is the bandwidth the same to the MPLS network from A and B?

I assume you have a router protocol running if  you redistribute the new default route at Site A  then traffic already going thru site A would use that route. 

Another way would be to use PBR to force certain subnets to go to the Internet via Site A

regards

Richard.