IP CEF load balancing test

IP CEF load balancing test



 33.33.33.33           -      f0/13    -           55.55.55.55
                     - R1 -                     - R2 -  
 44.44.44.44           -      f0/15    -            56.56.56.56


R1 = IPT-LAB-SWITCH
R2 = C3560-48


R1 is in OSPF totally stub area and receives two default route from R2

IPT-LAB-SWITCH#sh ip route ospf
O*IA 0.0.0.0/0 [110/2] via 10.0.15.5, 00:35:24, FastEthernet0/15
               [110/2] via 10.0.13.5, 00:35:24, FastEthernet0/13





IPT-LAB-SWITCH#sh ip cef exact-route 33.33.33.33 55.55.55.55
33.33.33.33 -> 55.55.55.55 => IP adj out of FastEthernet0/13, addr 10.0.13.5
IPT-LAB-SWITCH#sh ip cef exact-route 44.44.44.44 55.55.55.55
44.44.44.44 -> 55.55.55.55 => IP adj out of FastEthernet0/13, addr 10.0.13.5
IPT-LAB-SWITCH#sh ip cef exact-route 33.33.33.33 56.56.56.56
33.33.33.33 -> 56.56.56.56 => IP adj out of FastEthernet0/15, addr 10.0.15.5
IPT-LAB-SWITCH#sh ip cef exact-route 44.44.44.44 56.56.56.56
44.44.44.44 -> 56.56.56.56 => IP adj out of FastEthernet0/15, addr 10.0.15.5



R2 has specific routes from R1

C3560-48#sh ip route ospf
     33.0.0.0/32 is subnetted, 1 subnets
O       33.33.33.33 [110/2] via 10.0.15.3, 00:33:41, FastEthernet0/15
                    [110/2] via 10.0.13.3, 00:33:41, FastEthernet0/13
     44.0.0.0/32 is subnetted, 1 subnets
O       44.44.44.44 [110/2] via 10.0.15.3, 00:33:41, FastEthernet0/15
                    [110/2] via 10.0.13.3, 00:33:41, FastEthernet0/13

C3560-48#sh ip cef exact-route 56.56.56.56 33.33.33.33
56.56.56.56 -> 33.33.33.33 => IP adj out of FastEthernet0/13, addr 10.0.13.3
C3560-48#sh ip cef exact-route 56.56.56.56 44.44.44.44
56.56.56.56 -> 44.44.44.44 => IP adj out of FastEthernet0/13, addr 10.0.13.3
C3560-48#sh ip cef exact-route 55.55.55.55 33.33.33.33
55.55.55.55 -> 33.33.33.33 => IP adj out of FastEthernet0/13, addr 10.0.13.3
C3560-48#sh ip cef exact-route 55.55.55.55 44.44.44.44
55.55.55.55 -> 44.44.44.44 => IP adj out of FastEthernet0/13, addr 10.0.13.3


R1 seems load balanced between the links but NOT R2???

After change the load-sharing algorithm on R2:
C3560-48(config)#ip cef load-sharing algorithm universal FFFFFFFF


C3560-48#sh ip cef exact-route 55.55.55.55 33.33.33.33
55.55.55.55 -> 33.33.33.33 => IP adj out of FastEthernet0/13, addr 10.0.13.3
C3560-48#sh ip cef exact-route 55.55.55.55 44.44.44.44
55.55.55.55 -> 44.44.44.44 => IP adj out of FastEthernet0/15, addr 10.0.15.3
C3560-48#sh ip cef exact-route 56.56.56.56 44.44.44.44
56.56.56.56 -> 44.44.44.44 => IP adj out of FastEthernet0/15, addr 10.0.15.3
C3560-48#sh ip cef exact-route 56.56.56.56 33.33.33.33
56.56.56.56 -> 33.33.33.33 => IP adj out of FastEthernet0/13, addr 10.0.13.3

ip cef load-sharing algorithm

To select a Cisco Express Forwarding (CEF) load balancing algorithm, use the ip cef load-sharing algorithm command in global configuration mode. To return to the default universal load balancing algorithm, use the no form of this command.

ip cef load-sharing algorithm {original | tunnel [id] | universal [id]}

no ip cef load-sharing algorithm {original | tunnel [id] | universal [id]}

original	Sets the load balancing algorithm to the original based on a source and destination hash.
tunnel	Sets the load balancing algorithm for use in tunnel environments or in environments where there are only a few IP source and destination address pairs.
universal	Sets the load balancing algorithm to the universal algorithm that uses a source and destination, and ID hash.
id	(Optional) Fixed identifier.

IP Switching Commands: ip cef accounting through ip route-cache