OSPF load balancing questions

[jsyed]

Hi,

I have 3662 at zonal office which is connected to 7513 routers at zonal office.

Our head office has 2 wan routers doing wan aggregation for all the zonal office.

Two E1 links coming from each head office wan routers and connected to zonal office wan routers 7513. We are using each 7513 routers as backup in case of primary fails. But i noticed that traffic coming form user sites connected to 3662 is taking both routes means when I do sho ip route at first 3662 router I see it is taking routes to first wan router in zone center, now second 3662 router take wan routers two at zone centers.

I dont have multiple link going from same routers. OSPF does load balancing on same cost but not from two different router ?

Any explanation will be helpful.

javed

[a-vazquez]

OSPF does load balancing defnitely not from two different router but two different links on the same router.By default, Open Shortest Path First (OSPF) supports four equal cost paths to a destination.The multilink PPP feature can be used for load balancing purposes in cases there are multiple WAN links. One important thing to remember in terms of OSPF is the bandwidth of the multilink PPP. When multiple links are combined, the bandwidth of the multilink interface will change.

You can refer the following documents :

http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a0080094820.shtml

http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a008009481b.shtml#samplenetwork