EIGRP dynamically advertsing default gateway

[Steve Coady]

Hello

I do not understand how EIGRP chooses the ASA inside interface as the default gateway.

My ASA inside interface is the default gateway for my network. The route table shows this is dynamically

advertised via EIGRP.

                 0.0.0.0/0, ubest/mbest: 1/0
                   *via 10.0.4.253, Vlan500, [90/3072], 1d08h, eigrp-My-EIGRP, internal

The SVI is built on the Core devices.

interface Vlan500
  no ip redirects
  ip address 10.0.4.249/29
  no ip port-unreachable
  ip router eigrp My-EIGRP
  description ASAInside
  no shutdown

!

router eigrp My-EIGRP
  bfd
  autonomous-system 170
  router-id 10.0.250.3
  maximum-paths 3

The config on the ASA is:

interface GigabitEthernet0/1
 nameif inside
 security-level 100
 ip address 10.0.4.253 255.255.255.248 standby 10.0.4.254
 ospf cost 10
 summary-address eigrp 170 0.0.0.0 0.0.0.0 200

Please advise on how Eigrp knows that the Inside int on the ASA should be the default gateway.

[Jon Marshall]

Steve

On your ASA interface you have this -

summary-address eigrp 170 0.0.0.0 0.0.0.0 200

this tells EIGRP to advertise a summary route, the default route in your case, on that link. That link is connected to your core so the core receives this summary route.

Jon