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OSPF: equal cost paths

Occasional Contributor

OSPF: equal cost paths


I started with OSPF. Well, there´s ECMP load sharing mentioned. I´m asking myself where those equal cost paths are.

I added a picture.

- We have OSPF routers from A to I. Let´s say we take 4800G switch series.

- All black lines are 1 Gbit/s fiber lines

- Let´s say we have a host behind I and G

- The host behind I sends several data to the host behind G

Now, where are thos ECMPs?

- The whole path from I to G, i.e.GFABI (orange) and GEDCI (green)?

- Is it only between each router, e.g. we have 3 times 1 Gbit/s connections between E and D. Will there be a kind of load balancing?

- Is it both?



This message was edited by SmartU on 4-26-10 @ 8:50 AM
Occasional Advisor

Re: OSPF: equal cost paths

Well, looking at the "3Com Switch 4800G Family Configuration Guide-Release 2202-6W101" there is only few information about this topic:

On OSPF volume page 1-30:

"Configuring the Maximum Number of Load-balanced Routes

If several routes with the same cost to the same destination are available, configuring them as

load-balanced routes can improve link utilization."


On current release notes you´ll find:

"Modified features:

1. The maximum number of next hops in an ECMP set is changed from 4 to 8;"


Perhaps anyone knows how this is?

This message was edited by excelsio on 4-26-10 @ 11:42 AM