ASR9000 EIGRP internal routes

[evan-weiner]

Does anyone know how to make a connected route (loopback) distribute as internal to other EIGRP neighbors in the same ASN?  I did verify that a connected physical interface shows up as internal and that a loopback on a ASR1000 shows properly as internal.

interface Loopback2
 description Internet Routing
 ipv4 address X.X.X.253 255.255.255.255

IPv4-EIGRP AS(2): Topology entry for X.X.X.253/32
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 720896000, RIB is 5632000
Routing Descriptor Blocks:
0.0.0.0, from Rconnected, Send flag is 0x0
Composite metric is (720896000/0), Route is External
Vector metric:
Minimum bandwidth is 1000 Kbit
Total delay is 1000000000 picoseconds
Reliability is 250/255
Load is 100/255
Minimum MTU is 1500
Hop count is 0
External data:
Originating router is X.X.X.106 (this system)
AS number of route is 2
External protocol is Connected, external metric is 0
Administrator tag is 0 (0x00000000)

Thanks!

[Richard Burts]

Could you post your configuration of EIGRP? Are you using a network statement for the loopback or are you redistributing connected?

[pman]

If you want to advertise interface loopback 2 as internal then just delete the redistribute command.

you already advertise loopback2 as internal here:

router eigrp 2
address-family ipv4
interface Loopback2

[evan-weiner]

Thanks everyone for the replies.  

Keep in mind...A9K...EIGRP is different.  Apparently there is no network statement in EIGRP on it.  So in the meantime, I just added the interface to the EIGRP process and it seems to have resolved the issue.  Is that what everyone else would expect?

router eigrp 2
 address-family ipv4
  default-metric 1000 100 250 100 1500
  redistribute connected
  interface Loopback2
  !
  interface Bundle-Ether2
  !
  interface TenGigE0/0/0/3
  !
  interface TenGigE0/0/0/7

[pman · Accepted solution]

yes this is expected behavior because eigrp will always prefer internal routes over external routes.

so even if you have the:

redistribute connected

and at the same time the:

  interface Loopback2

The eigrp will prefer the route it learns as internal (D) over the external(EX)

[Peter Paluch]

Hello,

Awesome guidance and help. Rated as deserved!

One addition/clarification, if I may: You are correct that if EIGRP can pick between an internal or external network, it will prefer the internal one.

However, this rule applies to learned routes in EIGRP - that is, those that are already advertised in EIGRP. Here, the issue is slightly different: It is about preferring the particular method of injecting a route into EIGRP in the first place. If an interface is included in the EIGRP process both using the interface command and also covered by a redistribute connected command, the router will prefer the interface command and will inject the route as an internal route. Note - it won't inject it as both internal and external and then pick the internal as the best one. It will inject it only as an internal route, with no further choices.

In the end, the final result looks the same - it is as if the router preferred the internal route. However, in this case, we are not comparing two learned routes in EIGRP, rather, we are deciding how the route should even get into EIGRP. The interface command is always preferred to the redistribute connected command.

Admittedly, it is a subtle semantic difference - but I thought it is important to point it out.

Best regards,
Peter

[evan-weiner]

Thanks for the help.  This makes perfect sense.  A9K does EIGRP different than regular IOS and this little bit is all it was.