EIGRP offset-list changes metric despite no ACL configured

[snakayama]

Hello everyone,

I have a question about EIGRP offset-list behavior on Catalyst 3750 12.2(44)SE.
My customer informed me the following three cases and results.

Case 1
[Configuration]
offset-list 0 out 100 Vlan10
[Result]
Metric of all EIGRP routes outgoing through Vlan10 were added 100.

Case 2
[Configuration]
offset-list 1 out 100 Vlan10
access-list 1 permit 192.168.10.0
[Result]
Metric of the route matched access-list 1 (192.168.10.0) and if it is outgoing through Vlan10 was added 100.

Case 3
[Configuration]
offset-list 1 out 100 Vlan10
[Result]
Metric of all EIGRP routes outgoing through Vlan10 were added 100.

I think Case 1 and 2 are correct behavior but Case 3 is not.
Because there is no any ACL in Case 3.
I think no any EIGRP route's metric is changed, metric of all EIGRP routes outgoing through Vlan10 should be unchanged in Case 3.

In Case 3, customer did clear EIGRP neighbor and clear routing table but the symptom still occurred.

And customer tested Case 3 on another few IOS version, but same symptom still exit.

Do you have same experience?
Do you have any information about this behavior.

I searched known bug on bug toolkit, but I couldn't find any.

Your information would be appreciated.

Best regards,

Shinichi.

[Edison Ortiz]

It's not a bug but an expected behavior. 0 indicates all access lists.

Please refer to the documentation http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_eig2.html#wp1012264

Regards

Edison.

[snakayama]

Hello Edison,

Thank you very much for your reply.

I understand what you said if the access-list number is 0 in Case 1 I mentioned previously

However I would like to know about Case 3 means that the case of the access-list number is 1 not 0.

Case 3
offset-list 1 out 100 Vlan10

(without access-list 1)

Best regards,

Shinichi

[Edison Ortiz · Accepted solution]

Sorry, I misread your original post.

If you have an ACL listed in the offset-list and no ACL actually exist, the default behavior is permit any.

Regards

Edison.

[snakayama]

Hello Edison,

Thank you very much for your quick reply.

I understand it and your answer is what I wanted to know!

Do you know there is any documentation that describe what you said?

Best regards,

Shinichi

[Edison Ortiz]

Don't have one at the moment but you will see the same behavior with route-maps during route redistribution and access-groups applied to an interface.

Regards

Edison.

[snakayama]

Hello Edison,

Thank you very much for your quick reply again.
I understand you said.

Best regards,

Shinichi