[c-nsp] OSPF, load balancing

[Rodney Dunn]

Short answer: No. You can't get symmetrical
flows like this. The CEF hashing algorithm will hash uniquely
at Router A and Router B and while deterministic at the local
router it's nondeterministic at both points in regards to a flow
path.

Why do you care which way it goes unless there is some stateful firewall
or feature enabled on them?

On Wed, Mar 07, 2007 at 01:51:56PM +0100, Paolo Losi wrote:
> Dear friends.
> 
> We are now introducing OSPF in our small network.
> 
> There is a load balancing problem that we would like to cleanly
> address:
> 
>           |-router X-|
>           |          |
> router A-|          |-router B
>           |          |
>           |-router Y-|
> 
> the requirement for traffic flowing from A to B and B to A is:
> - each IP "flow" (ip dst, ip src, proto, etc.etc...) must cross
>    always the same router (X or Y) both in the forward that backword
>    direction.
> 
> Right now we are using route maps / rtr / track:
> 
> track 123 rtr 1 reachability
> 
> ip sla monitor 1
>   type echo protocol ipIcmpEcho XX.XX.XX.XX
>   frequency 10
> 
> route-map filter permit 10
>   match ip address access-list-foo
>   set ip next-hop verify-availability YY.YY.YY.YY 10 track 123
> 
> 
> is there a clean way to accomplish this with ospf?
> we would like to throw track away all toghether.
> 
> Thanks
> Paolo
> 
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