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Which Default Route will be preferred in Eigrp

Hi,

I am running EIGRP between two routers R1 and R2. R1 is the one which is connected to other networks and Internet. Instead of passing all those networks to R2, I would like to advertise a default network to R2 so that it can reach all those networks and internet connected to R1.

I have created a default route on R1 and I am redistributing it in Eigrp process. Also, i have configured ip summary-address eigrp 10 0.0.0.0 0.0.0.0 5 on the interface that is connecting to R2.

As per the above scenario which of the below default route should show in R2 and why?
D* 0.0.0.0 0.0.0.0 [5/x] via x.x.x.x
or
D*EX 0.0.0.0 0.0.0.0 [170/x] via x.x.x.x

I hope I have made myself clear. Kindly let me know if any more information is required.

Thanks in advance.

Don Johnston

As per the above scenario which of the below default route should show in R2 and why?
D* 0.0.0.0 0.0.0.0 [5/x] via x.x.x.x
or
D*EX 0.0.0.0 0.0.0.0 [170/x] via x.x.x.x

The first one. Since it has a lower administrative distance of 5.

Miftaul H

When there are multiple routes, the route with lowest AD is installed in the routing table.

I agree with donjohnston "D* 0.0.0.0 0.0.0.0 [5/x] via x.x.x.x" is in the r2 routing table due to the lowest AD of 5.

Vipin Kumar

ASKER

I agree with you, but when I check the Routing Table it is showing D*EX 0.0.0.0 0.0.0.0 [170/x] via x.x.x.x

I dont understand the reason behind it.

Can you help me understand why is it ending up in the routing table?

Don Johnston

Post the output of a "show ip eigrp topology".

Vipin Kumar

ASKER

The output of show ip eigrp topology and show ip route for R2 is mentioned below:

R2#sh ip eigrp topology
IP-EIGRP Topology Table for AS(10)/ID(10.212.155.1)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status

P 0.0.0.0/0, 2 successors, FD is 258816
via 10.212.140.21 (258816/28160), GigabitEthernet3/1
via 10.212.140.25 (258816/28160), GigabitEthernet4/1
P 10.212.254.15/32, 1 successors, FD is 2816
via Rstatic (2816/0)
P 10.212.154.0/25, 1 successors, FD is 2816
via Connected, Vlan302
P 10.212.155.0/24, 1 successors, FD is 2816
via Connected, Vlan401
P 10.212.152.0/30, 1 successors, FD is 2816
via Connected, GigabitEthernet3/2
P 10.212.140.20/30, 1 successors, FD is 256256
via Connected, GigabitEthernet3/1
P 10.212.153.0/24, 1 successors, FD is 2816
via Connected, Vlan301
P 10.212.140.24/30, 1 successors, FD is 256256
via Connected, GigabitEthernet4/1
P 10.212.152.8/29, 1 successors, FD is 2816
via Connected, Vlan101
P 10.212.152.16/28, 1 successors, FD is 2816
via Connected, Vlan102
P 10.212.152.32/28, 1 successors, FD is 2816
via Connected, Vlan201
P 10.212.154.128/25, 1 successors, FD is 2816
via Connected, Vlan104

R2#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is 10.212.140.25 to network 0.0.0.0

10.0.0.0/8 is variably subnetted, 11 subnets, 6 masks
S 10.212.254.15/32 [1/0] via 10.212.152.1
C 10.212.154.0/25 is directly connected, Vlan302
C 10.212.155.0/24 is directly connected, Vlan401
C 10.212.152.0/30 is directly connected, GigabitEthernet3/2
C 10.212.140.20/30 is directly connected, GigabitEthernet3/1
C 10.212.153.0/24 is directly connected, Vlan301
C 10.212.140.24/30 is directly connected, GigabitEthernet4/1
C 10.212.152.8/29 is directly connected, Vlan101
C 10.212.152.16/28 is directly connected, Vlan102
C 10.212.152.32/28 is directly connected, Vlan201
C 10.212.154.128/25 is directly connected, Vlan104
D*EX 0.0.0.0/0 [170/258816] via 10.212.140.25, 1w4d, GigabitEthernet4/1
[170/258816] via 10.212.140.21, 1w4d, GigabitEthernet3/1

Don Johnston

The default route doesn't show in the topology table.

Need to see the config of R1

Miftaul H

This topology table is from router2, we wont see default route here. We need to see the topology table and the config of R1.

Don Johnston

This topology table is from router2, we wont see default route here.

Actually, the default route is in the topology table. Just not the one we're looking for.

Miftaul H

I meant to see something like below which isn't there

P 0.0.0.0/0, 1 successors, FD is 28160
        via Rstatic (28160/0)
        via Summary (28160/0), Null0

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Miftaul H

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