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EIGRP redundancy - feasibility condition equal?

_|brt.drml|_
Level 1
Level 1

Situation:

I have two spoke routers, both have a leg to the ISP (my hub router).

All are connected and routing with EIGRP. 

 

I connected both spoke routers with a physical cable. Both are forming direct EIGRP neighborship. 

However, both spokes only route traffic trough the direct connected HUB interface. 

Both spokes do send routing information over the 'direct' link. Yet, no load balancing occurs... 

The "sh ip eigrp topology" only shows known topology routes (feasible successors). 

The "sh ip eigrp topology all-links" does show known routes via the physical connection. 

 

Intent:

We can manipulate HSRP for the vlan's so both routers are routing traffic, but that is not load balancing...

I thought that both spokes would perform load balancing... 

 

Question:

Is poison reverse the issue? In 'sh ip eigrp events' I notive drops and infinite... 

Is it even possible to create load balancing at all? 

 

Any thoughts? 

 

Thank you

 

1 Accepted Solution

Accepted Solutions

Hello @_|brt.drml|_ ,

either you can make the two spoke routers active HSRP routers for diffferent HSRP groups in different VLANs.

This is actually a way to achieve some load sharing per source prefix / VLAN.

Alternatively you could use PBR Policy Based Routing to select some traffic flows to be sent  to the other Spoke.

 

The first approach works if you have  at least two user facing VLANs / IP subnets.

 

Hope to help

Giuseppe

 

View solution in original post

5 Replies 5

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello @_|brt.drml|_ ,

in EIGRP the feasible condition FC requires that the Reported distance RD is strictly less then the current Feasible Distance on the local node.

The reason for this is that the FC is one component of the loop avoidance properties of EIGRP DUAL algorythm : use only alternate paths coming from a device that is more near to the destination then the local node.

Tha more near translates in RD < FD.

if RD = FD does not satisfy the FC condition.

In your topology each Spoke advertises the prefixes to the other one othe shared link but the FC is not satisfied.

As a result of this no load balancing happen even not equal cost Multi Path using variance value greater then 1.

For unequal multi path load balancing to happen  the FC rule need to be satisfied with RD < FD.

 

Waht you see is normal with EIGRP with your topology

 

Hope to help

Giuseppe

 

Thought so



Any thoughts to enable the load balancing. Probably using my HSRP is the best option?




Hello @_|brt.drml|_ ,

either you can make the two spoke routers active HSRP routers for diffferent HSRP groups in different VLANs.

This is actually a way to achieve some load sharing per source prefix / VLAN.

Alternatively you could use PBR Policy Based Routing to select some traffic flows to be sent  to the other Spoke.

 

The first approach works if you have  at least two user facing VLANs / IP subnets.

 

Hope to help

Giuseppe

 

Giuseppe THANK YOU

 

_|brt.drml|_
Level 1
Level 1

Found a good solution with the offset list. I overlooked this option. I changed the incoming metric with adding '1' so the feasibility condition did take place.

 

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