2 default-gateways and 1 EIGRP process

[Mark Mattix]

I was wondering if someone could offer advice on how I should setup my EIGRP routing process. I have a simple network of R0---R1---R2---R3.

Currently R2 has a static 0.0.0.0 default route to R3 to the Internet. R2 has an EIGRP process setup with R0 and R1 to redistribute this static default route for Internet access. Soon R1 will get it's own Internet connection so R1 and R0 will connect to the internet on R1 and no longer through R3.

My question is, how can I implement this new Internet route on R1 without affecting the default gateway on R2 (which is via R3). In my lab I changed the bandwidth metric on R1 going to R2 lower than the bandwidth metric of the new Internet line. This didn't seem to make any difference in the routing table, R1 was still using the default route learned via R2's EIGRP process.

Thanks for any advice!  -Mark

[Mark Mattix]

Also, I thought of just configuring a new static route for the default-gateway on R1 but am concerned that R1 would share this with R2 since the redistribute static command needs to be configured on R1. The static route would have a lower AD value than the EIGRP route but I can't have R2 trying to send Internet traffic out R1.

Well now that I think about this I'm wondering...

If R1 has a configured static route the AD value would be 0. The default route from the EIGRP process would be 90. If R1 shared it's static route to R2 that route would have the AD value of 90, correct? If R2 still has it's static route configured that AD value should be 0, thus would static routes on R1 and R2 work for seperate default-gateways?

[cadet alain]

Hi,

so now r1 and r0 are receiving the 0.0.0.0/0 route via EIGRP and it is a D EX route with an AD of 170 and when r1 will have a static default of its own it will get to r0 via EIGRP redistribution on r1 ?

will r1 still be an eigrp neighbour with r2 ?

Regards

Alain

Don't forget to rate helpful posts.

[acampbell]

Mark,

I would add 2 default routes as statics

R1

ip route 0.0.0.0 0.0.0.0 NEW INTERNET ADD AS NEXT HOP

R0

ip route 0.0.0.0 0.0.0.0 R1 AS NEXT HOP

Both of these routers will see the default route as an AD of 1

This is better than the AD of 90 from EIGRP

These will not be propogated to EIGRP unless you tell them to.

So R2 will still see the its default route via R3 not R1 or R0

Regards,
Alex.
Please rate useful posts.

[Mark Mattix]

Alain:

so now r1 and r0 are receiving the 0.0.0.0/0 route via EIGRP and it is a D EX route with an AD of 170: Correct

and when r1 will have a static default of its own it will get to r0 via EIGRP redistribution on r1: That's what I intend

will r1 still be an eigrp neighbour with r2: Correct

Acampbell:

I like your idea of adding the static routes to R1 anf R0 but beyond R0 are actually 2 more routers that I didn't mention, I didn't nmention them because I assumed to keep EIGRP which would distribute the default gateway on R1 to them.

These will not be propogated to EIGRP unless you tell them to. R1 has the redistribute static command configured, this is because there are other routes that must be distributed. Is there a way to not redistribute a specific static route you have configured?

Thanks!!

[cadet alain]

Hi,

yes you can decide which static route to redistribute with a route-map and a prefix-list but if you have 2 0.0.0.0/0 , how will you differentiate them unless you tag them. So you would have to tag the routes when redistributing them and filter them according to their tag values on the receiving routers.

Regards

Alain

Don't forget to rate helpful posts.

[Mark Mattix]

Thank you for that information. Do you think a change in the bandwidth command on R1's interface going to R2 would be enough to have R1 use it's new default route out to the Internet? I thought by doing this I could still have the route to the internet from R2 as a backup for R1 if it's connection ever fails.

[cadet alain]

Hi,

bandwidth and delay will influence the EIGRP metric but it is highly discouraged to use bandwidth for this.

could you post your topology diagram because i suppose these aren't just back-to-back topology, ain't it ?

Regards

Alain

Don't forget to rate helpful posts.

[Mark Mattix]

       

[Mark Mattix]

So in my lab I configured R1 with a static route out to the new Internet connection. This worked but what I didn't think of is, because I have the static route configured on R1, R1 continues to try and send data out this port even when it's down, it doesn't switch to allowing EIGRP to populate the routing table with the second route to the internet from R3.

Is what I want to accomplish by having a secondary default route to the Internet only possible with a redudancy protocol like HSRP? Even if I changed the metrics on my interfaces I'd still need the static route command to populate the routing table on R1.

[blau grana · Accepted solution]

Hello Mark,

Sometimes Ethernet interfaces are not functional even if they are in up/up state. You should configure IP SLA on R1&R3 to track reachability of next hops to internet. If links are working, default routes toward internet will be injected into routing table and can be redistributed into EIGRP.

On R1&R2 interfaces toward VPN configure very high delay so local default routes will be prefered.

Best Regards

Please rate all helpful posts and close solved questions

[Mark Mattix]

Thanks for your reply Blau. I've been doing some research and came upon IP SLA, I've already spent the last 2 hours reviewing it. I was thinking this sounds best to accomplish what I need and you mentioning it only confirms that for me! Thanks!

[Mark Mattix]

blau grana, I have one more question. If I have IP SLA running and it's injecting the default route into the routing table of the new internet connection on R1, will this route also be shared via EIGRP to router's R0 and below?

[paul driver]

Hello
I don't understand your setup at present would nice to see. Topology

Int xx
Ip summary- address eigrp xxx 0.0.0.0. 0.0.0.0.0 x ( admin distance - higher least preferred)

Apply this to each router interface facing the recipient of the default

Res
Paul

Sent from Cisco Technical Support iPad App

[Mark Mattix]

pdriver, there's a topoloy posted above. It seems like IP SLA will work out for me but I will look into the commands you posted. Also, I know it isn't suggested (not sure why though) but could changing the bandwidth command on the new internet link's interface and making the metric higer than the link over to R2, also solve my problem?