BGP: Multihomed Customer to Single ISP in Load-Sharing Setup with Static Routes

Outbound Traffic (CE to PE):
- each customer router uses closest CE as exit point;
- CE routers must be collocated to have load-sharing;

Inbound/Return Traffic (PE to CE) (pre-IOS 12.2):
- true load-sharing is impossible to achieve with multiple PEs;
- per BGP route selection, only one route will be the best route (to the customer network)
- can be optimized by dividing the customer address space

Customer Network: 11.2.3.0 /24
Customer Network "division" assigned to PE1: 11.2.3.0/25
Customer Network "division" assigned to PE2: 11.2.3.128/25

Configurations:

PE1 Config: ! ip route 11.2.3.0 255.255.255.128 serial 0 tag 1000 ip route 11.2.3.0 255.255.255.0 serial 0 tag 1000 ! router bgp 123  redistribute static route-map INTOBGP  ... !

PE2 Config: ! ip route 11.2.3.128 255.255.255.128 serial 0/0 tag 1000 ip route 11.2.3.0 255.255.255.128 serial 0/0 tag 1000 ! router bgp 123  redistribute static route-map INTOBGP  ... !