Hi you can use EIGRP with variance to do unequal cost load balancing
and use BGP to achieve that too using dmz link bandwidth
http://www.cisco.com/c/en/us/td/docs/ios/12_2s/feature/guide/fsbgplb.html
Configuring BGP Link Bandwidth
To configure the BGP Link Bandwidth feature, perform the steps in this section.
SUMMARY STEPS
1. enable
2. configure {terminal | memory | network}
3. router bgp as-number
4. address-family ipv4 [mdt | multicast | tunnel | unicast [vrf vrf-name] | vrf vrf-name] | ipv6 [multicast | unicast] | vpnv4 [unicast]
5. bgp dmzlink-bw
6. neighbor ip-address dmzlink-bw
7. neighbor ip-address send-community [both | extended | standard]
8. end
HTH
Hitesh
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