05-03-2020 10:31 AM - edited 05-03-2020 08:40 PM
I have a simple EIGRP topology with 3 routers and 2 AS. I have created a summary route for 192.168.X.X network with /21 and advertised on R2 both serial interfaces(s2/0,s2/1). I have also redistributed both EIGRP AS into each other. However, when R3 receives route for 192.168.x.x network it shows it's learned via external route. Why is that happening even though I have summarized the same route out of both interfaces on R2?
R1#sh ip route eigrp
D 192.168.0.0/21 [90/2297856] via 10.2.2.2, 00:00:11, Serial2/0
R3#sh ip route eigrp
D EX 192.168.0.0/21 [170/2297856] via 10.4.4.1, 00:00:05, Serial2/1
*****************************************************************************
R2#sh run int s2/0
interface Serial2/0
ip address 10.2.2.2 255.255.255.252
ip summary-address eigrp 100 192.168.0.0 255.255.248.0 5
serial restart-delay 0
end
R2#sh run int s2/1
interface Serial2/1
ip address 10.4.4.1 255.255.255.252
ip summary-address eigrp 200 192.168.0.0 255.255.248.0 5
serial restart-delay 0
end
*****************************************************************************
R2#sh run | sec router
router eigrp 100
redistribute eigrp 200
network 10.0.0.0
network 192.168.0.0 0.0.255.255
no auto-summary
router eigrp 200
redistribute eigrp 100
network 10.0.0.0
network 192.168.0.0 0.0.255.255
no auto-summary
******************************************
05-04-2020 02:18 AM
Hi @Gucamole
It seems that's how EIGRP behaves - only one summary route gets installed whichever EIGRP process has lower AS number. In your case it's AS 100 so the summary route for AS 200 will be redistributed hence it shows up as external.
The best way would be redistributing static route on both AS.
05-04-2020 03:11 AM - edited 05-04-2020 03:17 AM
Hi
do the following
1. dont enable EIGRP on R2 for 10.0.0.0 but use the exact subnet mask (because 10.0.0.0 will enable both AS numbers on each serial interface which is wrong)
2. when you redistribute on R2 between the two EIGRP AS's use the route-map option
and the route-map should match access list for the IP's of the EIGRP AS IP's only.
check the configs attached
05-04-2020 05:05 AM - edited 05-04-2020 05:11 AM
Hello
Given that topology, you could simplify by removing the redistribution from both eigrp processes and make each AS spoke a stub and advertised a default to each rtr rom R2
R2
router eigrp 100
no redistributie eigrp 200
eigrp stub summary
router eigrp 200
no redistributie eigrp 100
eigrp stub summary
R1/R3
router eigrp x00
eigrp stub
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