Not too much related with security
There are 4 routes, in circle shape: R1>R2>R4 and R1>R3>R4.
- R2 -
R1 - - R4
- R3 -
I configured a EIGRP AS 1 for R1-R2-R4 and AS 3 for R1-R3-R4. It means
router R1 and R4 have 2 ASs running on each
At R4 I created a loopback with address 4.4.4.4/32 and added it to both
eigrp AS's
R4
router eigrp 1
network 4.4.4.4 0.0.0.0
network 10.0.24.0 0.0.0.255
no auto-summary
router eigrp 3
network 4.4.4.4 0.0.0.0
network 10.0.34.0 0.0.0.255
no auto-summary
The interesting is on router R1, I am getting the following
IP-EIGRP Topology Table for AS(1)/ID(1.1.1.1)
P 4.4.4.0/24, 1 successors, FD is 435200
via 10.0.12.2 (435200/409600), FastEthernet0/0
IP-EIGRP Topology Table for AS(3)/ID(1.1.1.1)
P 4.4.4.0/24, 0 successors, FD is Inaccessible
via 10.0.13.3 (435200/179200), FastEthernet0/1
I have read about FD inaccessible and it seems the route is just preferable
to go over R2 instead of R3 and in case of R2 failure, It would have R3
forwarding. I tested that and it worked fine.
The question is:
Why did EIGRP choose to forward over R2 with AD 409600 instead of R3 with AD
179200? I changed the bandwidth at R3 to be more attractive but even after
this change R2 is still the chosen guy. The FD is the same to both. I did
not make any changes on K values
Is there any precedence in case of match to go over the minor AS number?
Any comments would help
--
Bruno Fagioli (by Jaunty Jackalope)
Cisco Security Professional
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