can we do load balance on ospf ??

ohammoudeh · ‎06-23-2010

we have 1 router (A) connected with 2 router(B,C) with ospf , we need router A to do load balance on B,C .

the problem that router A send the traffic to router B and did not send to router C , we do check in routing table on router A we found the no route to the router C so router A did not send traffic to router C .

we do the following test . we disconnect router B that it is working well and let router C connected to router A . router A become active with router A start sending packet to the router C .

so we need to connect router B,D to router A and router do load balance to router B,C . can we do this

Ganesh Hariharan · ‎06-23-2010

we have 1 router (A) connected with 2 router(B,C) with ospf , we need  router A to do  load balance  on B,C .
the
problem that router A send the traffic to router B and did not send to 
router C , we do check in routing table on router A we found the no
route to the router C so router A did not send traffic to router C .
we
do the following test . we disconnect router B that it is working well
and let router C connected to router A . router A become active with
router A start sending packet to the router C .
so we need to connect router B,D to router A and router do load balance to router B,C . can we do this

Yes, OSPF supports equal cost load balancing. If the cost of the links are the same, OSPF will insert both routes into the routing table. Also you can force the cost of the links (even if the links are not equal cost) so that both routes are accepted as equal cost routes by router A.

The route that will be selected for sending a packet will ultimately depend on the switching type (Fast switching, cef, etc) configured on router A.

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

Hope to Help !!

Ganesh.H

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Dasuntha Dinesh · ‎06-23-2010

Yes, You can override the default cost by manually define the cost using the ip ospf cost interface-cost command on a per-interface basis. The lower the number, the better the link and more strongly preferred.

Regards,

Dasuntha

ohammoudeh · ‎06-23-2010

thank all for replay.

if router A is replaced with core switch and 2 port that connect to B,C is switch port .

how can i do ospf load balance

Dasuntha Dinesh · ‎06-23-2010

Its the same.

configure ospf cost in each interface in core switch where Router B & Router C connecting.

Regards,

Dasuntha

ohammoudeh · ‎06-23-2010

if the ports that router B,C on the core switches are L2 and ip ospf cost not allowed , what can i do

Dasuntha Dinesh · ‎06-23-2010

What is the model of your core switch?

If your core switch is a L3 switch, you can configure "no switchport" command in Interfaces connecting Router B & C.

Then the ports will convert to L3. And you can assign IP Address also...

Regards,

Dasuntha