Is there a solution for 2 Default Routes with EIGRP and this topology?

[shlomim]

I'm using IOS/IOS XE, EIGRP Named mode.

I've been tasked to find a solution for this following topology:
There are two edge routers (R14 and R15), both have static default route, both need to advertise it via EIGRP.

R14 is connected to R3, R15 connected to R4, and R3 connected to R4:

0.0.0.0/0----R14----R3----R4---R15----0.0.0.0/0

The solution that I've been asked to do with EIGRP is that R3 will use both R14 and R4 default route (variance), and R4 should use both R15 and R3 default route.

yet it seems that I can solve it only on a single way, if I make sure that R4 RD (Reported Distance) for the default route will be smaller than R3 FD for the default route - R3 will install both routes using the Variance command.

BUT in this case R3 RD for the default route will be bigger than R4 FD - and R4 will not install the default route from R3.

any suggestion ? is there a feature in EIGRP named mode that can solve my issue ?

[MHM Cisco World · Accepted solution]

It hard to do that in eigrp' where any change in one link factors will effect all router in same eigrp AS' 

With BGP is easy 

With two eigrp and use redistrubte I think also it can done 

With one eigrp as it impossible' sorry 

MHM

[Jens Albrecht]

Hello @shlomim,

the parameters you are looking for can be set under the 'topology base'.

An example setting the variance to '2' and doing load-balancing based on the metric looks as follows:

router eigrp EIGRP
 address-family ipv4 autonomous-system 100
  topology base
   variance 2
   traffic-share balanced
  exit
 exit-address-family

Of course, you need to verify and set the correct value for the 'variance' as needed.

HTH!

[M02@rt37 · Accepted solution]

Hello @shlomim 

Totally agree with MHM, in a single EIGRP AS, symmetric defaut multipath routing using 'variance' is practicaly unachievable without extremely tight and fragile tuning. It is better to use 2 AS with redistribution or switch to a protocol like BGP if you need more control...

[julian.bendix · Accepted solution]

I would go for 2 EIGRP AS in your case. With one AS always only one Default Route will be installed, since one will always win over the other... well not always but achieving this is simply too fragile and uneasy to operate and troubleshoot

[paul driver]

Hello
unless i’m am missing something completely obvious please accept my apologies in advance

 But based on your OP with all links  being equal R3 would choose R14 and R4 would choose R15 by default 
The composite metric of either defaults on R3-4 would be ratio of 2 anyway - and even IF variance worked in this case which i doubt it would - the question is why would you want to allow R3-R4 have a default pointing directly at each other as-well - be it with eigrp or bgp