From R1, you want to BGP load balance out to R2, R3.
In order to do BGP load balancing, the route selection must be the same up to 5.5. I had thought it was at 8.5, but after testing, it's at 5.5.
1 Weight
2 Local pref
3 Self-originated next hop = 0.0.0.0)
4 AS Path
5 Origin i, then, e, then, ?
5.5 --note: When "bgp bestpath as-path multipath-relax" is used, it's actually at this point it will load balance when above 3 are the same. Not anything else below. Any else below don't matter. If above 5 are the same for that route, it will load balance when do a "show ip route" will see 2 routes there.
6 Med (metric)
7 external ebgp over igp
8 IGP cost
8.5 --Max Path Checks -- If all above are the same for a route with multiexit points, will load balance. Put in routing table. Will see 2 routes in "sh ip ro", then you know it's load balanced.
R1(config)#
router bgp 100
maximum-paths 2
bgp bestpath as-path multipath-relax (A hidden Command).
9 Ebgp peering -older routes better
10 rid lower
R1#sh run | s bgp
router bgp 1
no synchronization
bgp log-neighbor-changes
bgp bestpath as-path multipath-relax
network 1.1.1.1 mask 255.255.255.255
neighbor 192.168.12.2 remote-as 2
neighbor 192.168.12.2 soft-reconfiguration inbound
neighbor 192.168.12.2 route-map SET-MED-ASPATH in
neighbor 192.168.13.3 remote-as 3
neighbor 192.168.13.3 route-map SET-ORIGIN-IGP in
maximum-paths 2
no auto-summary
=====
R1#sh ip bgp
m multipath,
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*m 5.5.5.5/32 192.168.12.2 999 0 2 2 5 i
*> 192.168.13.3 3 0 3 4 5 i
R1#
R1#sh ip route
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
5.0.0.0/32 is subnetted, 1 subnets
B 5.5.5.5 [20/999] via 192.168.13.3, 03:14:22
[20/999] via 192.168.12.2, 03:14:22
192.168.12.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.12.0/24 is directly connected, FastEthernet0/1
L 192.168.12.1/32 is directly connected, FastEthernet0/1
192.168.13.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.13.0/24 is directly connected, FastEthernet0/0
L 192.168.13.1/32 is directly connected, FastEthernet0/0
R1#