VRF-Lite issue with ip summary-routes

Answered Question
Apr 15th, 2007

Hi All,

I'm relatively new to VRF-Lite and need some help please.

I've implemented a vrf-lite config, edited config below contains the interesting bits.

Does anyone know if there are any issues between using 'rd1:1' with 'router eigrp 1', that may affect propogation of CUST_A's eigrp summary-routes?

CUST_B is distributing summary-routes successfully but CUST_A cannot (Both have routers directly connected to this router). There is a summary-route '172.17.64.0/18' on the neighbouring router. All other routes are fine, except any summary-routes. The FD for the CUST_A summary-route is seen as 4294967295 & hence 'Inaccessible'.

The only thing I can think of is if there is a reason, which I'm unaware of, that I shouldn't be using 'router eigrp 1' and rd1:1 for a customer. But I can't find anything that states so.

Cheers for any help

===================

!

ip vrf CUST_A

rd 1:1

!

ip vrf CUST_B

rd 10:1

!

router eigrp 1

no auto-summary

!

address-family ipv4 vrf CUST_B

network 10.0.0.0 0.0.0.7

network 10.0.0.16 0.0.0.7

network 192.168.253.0

no auto-summary

autonomous-system 10

exit-address-family

!

address-family ipv4 vrf CUST_A

network 10.91.0.0 0.0.0.3

network 151.178.254.208 0.0.0.3

no auto-summary

autonomous-system 1

exit-address-family

I have this problem too.
0 votes
Correct Answer by Harold Ritter about 9 years 9 months ago

You get the same behavior with or without VRF. If the prefix cannot be installed in the RIB, EIGRP sets the FD to inaccessible and therefore doesn't propagate it to any neighbors.

To fix the issue just remove the static from the specific VRF.

Hope this helps,

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Harold Ritter Mon, 04/16/2007 - 09:59

David,

The FD being set to 4294967295 usually means that this route is already installed in the RIB from another source having a better admin distance. See if this is the case for 172.17.64.0/18 in VRF CUST_A.

Hope this helps,

dlongworth Mon, 04/16/2007 - 15:43

I've had to insert a static route temporarily, but I've never seen an FD of this magnitude. All other routers (although non-vrf) show an FD=3328 for the same summary-route originating from the same router.

Harold Ritter Mon, 04/16/2007 - 16:18

The FD is simply set to inaccessible (0xffffffff = 4294967295) and as I mentioned before, probably because the specific prefix was already installed in the RIB (VRF CUST_A) from another source with a lower admin distance. Have you been able to verify this?

Hope this helps,

dlongworth Mon, 04/16/2007 - 17:21

The only other possible source is the locally configured static route. But I've never seen this before.

I've had routers with statics and eigrp routes; obviously the routing-table prefers the static but the eigrp FD was always calculated and remained around in the thousands, never set like this.

Is this something specific to VRF?

DC-VRF-One#sh ip ro vrf CUST_A 172.17.64.0

Routing entry for 172.17.64.0/18

Known via "static", distance 1, metric 0

Routing Descriptor Blocks:

* 151.178.254.210

Route metric is 0, traffic share count is 1

DC-VRF-One#sh ip ro vrf CUST_A static

172.17.0.0/18 is subnetted, 3 subnets

S 172.17.128.0 [1/0] via 151.178.254.217

S 172.17.192.0 [1/0] via 151.178.254.210

S 172.17.64.0 [1/0] via 151.178.254.210

DC-VRF-One#sh ip eigrp vrf CUST_A top 172.17.64.0 255.255.192.0

IP-EIGRP (AS 1): Topology entry for 172.17.64.0/18

State is Passive, Query origin flag is 1, 0 Successor(s), FD is 4294967295

Routing Descriptor Blocks:

151.178.254.210 (TenGigabitEthernet1/4), from 151.178.254.210, Send flag is 0x0

Composite metric is (3840/3584), Route is Internal

Vector metric:

Minimum bandwidth is 1000000 Kbit

Total delay is 50 microseconds

Reliability is 255/255

Load is 1/255

Minimum MTU is 1500

Hop count is 4

DC-VRF-One#

Correct Answer
Harold Ritter Mon, 04/16/2007 - 17:51

You get the same behavior with or without VRF. If the prefix cannot be installed in the RIB, EIGRP sets the FD to inaccessible and therefore doesn't propagate it to any neighbors.

To fix the issue just remove the static from the specific VRF.

Hope this helps,

dlongworth Mon, 04/16/2007 - 18:15

Ah! I perceive my misunderstanding. Bit of a wild goose chase there.

Being new to VRF-lite, I thought it was my VRF-Lite config that was doing something to EIGRP.

A case of over-analyzing my problem; skipping the fundamentals.

Thank you for your assistance, it was very helpful.

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