IS-IS --> EIGRP redistribution issue

Hey all. Hopefully this isn't something retarded. I've done some reading mixed with some hands on..trying to lock down IS-IS so I don't bomb the BSCI. Here's my scenario....

Lo1

(R2)--s1/0

s1/0--(R1)--s2/0

s2/0---(R3)

Lo1

R2 Loopback1: 2.2.2.2
R2 s1/0: 192.168.1.1
R1 s1/0: 192.168.1.2
R1 s2/0: 192.168.1.5
R3 s2/0: 192.168.1.6
R3 Loopback1: 3.3.3.3

R2 and R1 are part of the IS-IS area 49.0001, and R1's s2/0 and R3 are in EIGRP AS 100. I am trying to perform mutual redistribution between the two at R1.

For whatever reason..R2 has 100% of the routes in the network...but R3 is lacking a route to 192.168.1.1 (R2's s1/0). As a result, pings from R2 to R3 fail, since R3 has no route back. I verified this by creating a static route from R3 to R2...which works fine. So my issue is, R3 is not receiving a route for 192.168.1.1.

I've been debugging..it seems R1 is hearing nothing about the 192.168.1.1 network, but only knows of it because it's directly connected. The EIGRP process does not have the route anywhere in it's topology either.

I'm focusing my troubleshooting efforts on R2, since it seems to not be sending the route out, but I have no idea why.

For a bit of a breakdown...

R1 on the IS-IS side is a Level-1-2, R2 is a Level-1-2 as well..by default, but I also tried fooling around with that..to no avail...

Find more posts tagged with

SAVE $250 on Your CISCO Boot Camp — Use Code "EXAM26"

Exclusively for TechExams members for Infosec Boot Camps starting before April 30, 2026

View CISCO Boot Camps

Comments

lildeezul

Hi hopefully this helps..

In Eigrp are you redistributing the connected routes..

Because R1 is perfoming the distribution, and r1 connected route to the isis domain is the 192.168.1.0 /30 network, correct ?

If thats the case, you have to redistribute the connected route thats in the isis domain into the eigrp process via the Redistribute connected command

Mrock4

You are the man........redistribute connected metric yad yad yada in the eigrp process got it working...........awesome..

lildeezul

Glad i could help.

Mrock4

I can't believe that's all it was..I'm going to look into this further too.

kryolla

are you using a route map for redistribution or are you just doing

router eigrp 100
redistribute isis metric 1 1 1 1 1

router isis
redistribute eigrp 100

Mrock4

kryolla wrote:

are you using a route map for redistribution or are you just doing

router eigrp 100
redistribute isis metric 1 1 1 1 1

router isis
redistribute eigrp 100

I was just using the redistro commands with metrics added to both. Redistribute connected worked. I didn't even think of that. Right now I'm just trying to get a solid grip on IS-IS operation and troubleshooting...I was totally side swiped on the BSCI by IS-IS. I appreciate the help a lot. I'm sure I'll need more in the near future.

kryolla

I was doing some research on why you had to redistribute connected under router eigrp 100 as I didn't understand why when you dont have to do that for any other IGP and found out it is only unique to ISIS. Good to know I guess if you work with ISIS

_maurice

I dont want to say why, but it is very good that you learned about the redistribute connected command :P

kpjungle

Ran into the same problem, here is some lab results that confirm it:

ISIS and OSPF:
OSPF does NOT import the ISIS link between R2 and R3 into the OSPF domain.
ISIS does import the OSPF link between R1 and R2 into the ISIS domain.

RIP and OSPF:
OSPF does import the RIP link between R1 and R2 into the OSPF domain.
RIP does import the OSPF link between R2 and R3 into the RIP domain.

RIP and EIGRP:
RIP does import the EIGRP link between R2 and R3 into the RIP domain.
EIGRP does import the RIP link between R1 and R2 into the EIGRP domain.

EIGRP and ISIS:
EIGRP does NOT import the ISIS link between R2 and R3 into the EIGRP domain.
ISIS does import the EIGRP link between R1 and R2 into the ISIS domain.

EIGRP and OSPF:
OSPF does import the EIGRP route between R1 and R2 into the OSPF domain.
EIGRP does import the OSPF route between R2 and R3 into the EIGRP domain.

Mrock4

Yeah..it threw me off because with other protocols you usually don't have to add that statement to advertise that particular route. If it was OSPF, it would have been fine....definitely unique to IS-IS. I hope everyone can learn from my experience!!! I'm going to come up with a new lab tonight to verify this stuff, and put it all together...

On a separate note, I acquired a large white board from work that was going to be trashed, and now have topology maps written all over it...it's a great thing

cisco_trooper

Alrighty rock,

what if you start advertising your loopbacks into your IGPs? do THOSE routes make it from your EIGRP domain into your ISIS domain and vice versa?

Mrock4

The loopbacks are already on the edge routers..they did come across, but I got some wacky **** here and there. IS-IS is very moody at times..