OSPF: equal cost paths

[SmartU]

Hi,





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?

http://img231.yfrog.com/img231/7017/ecmp.png

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

[excelsio]

Well, looking at the "3Com Switch 4800G Family Configuration Guide-Release 2202-6W101" http://support.3com.com/documents/switches/4800G/Switch_4800G_CG_R2202_6W101.pdf 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 http://support.3com.com/documents/switches/4800G/Switch_4800G-CMW520-R2202P15_Release_Notes.pdf 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