BGP load balancing

[aliyevzaur1989]

Hello. In our company (ISP) we have 2 core routers (ASR9K) and 2 BRASes (ASR9K). One BRAS acts as a gateway for users to which are assigned NAT IP addresses and the other for users to which are assigned public IP addresses. I want to mention that the great part of users are on "NAT BRAS".

Each of the core routers has 2x10Gbps uplink connection  (the connection diagram is attached). My problem is, in one of the core routers' uplink gets fully loaded in the rush hours. But the other routers' uplink is loaded ~50-60%.  Can someone help me to set up the load balance?

Thanks

[AARON WEINTRAUB]

Do the two CGN routers both have their own EBGP session to AS-Y?  Is the problem with traffic flow from AS-X to AS-Y or the other way around?  How many prefixes does AS-X advertise to AS-Y?  Are both CGN routers getting full routes from AS-Y?

[aliyevzaur1989]

Yes routers have own EBGP sessions to AS-Y.  The problem is with the traffic form AS-Y.  What i want to do is to load balance the traffic with "local preference". Is it possible?  

[AARON WEINTRAUB]

If the traffic is coming in from AS Y (to you) then it depends what sort of communities the AS Y offers to manipulate the route attributes on their routers.  If you are advertising multiple prefixes to AS Y, then you can prepend or use some communities to try to shift the traffic between the connections.