How to configure Administrative Distance

Lessons Discussion
1

This topic is to discuss the following lesson:

https://networklessons.com/cisco/ccie-routing-switching/how-to-configure-administrative-distance/

2

Hello Rene,

about access-lists, I have to read in this way for prefix 1.1.1.0/24:

My local router which runs OSPF, RIP, and EIGRP has to put in the routing table that was learned by RIPā€¦is my reasoning correct?

Well, we use an access-list to permit that prefix is handled only by RIP?

3

Hi Rene,

Thanks for your postā€¦
Really a very helpful ans straight forward explanation clearing all doubtsā€¦
Thanks a lotā€¦

4

You are welcome Farhan!

5

Can you please clarify for me?
What is the difference between inter-area and intra-area on ospf?

6

Intra-area means within the area and inter-area means another area.

7

Thanks

8

I donā€™t get this:

James(config-router)#distance 70 0.0.0.0 255.255.255.255 MY_PREFIXES

What is the meaning of 0.0.0.0 255.255.255.255?

9

Hi Crytsuone,

0.0.0.0 255.255.255.255 refers to all networks. If we wouldnā€™t specify the access-list, the AD would change for all networks.

Rene

10

Hi Rene,
Do the RIP admin distance changes only apply locally or will they be passed on to other RIP routers with the new admin distance?

11

Hi David,

Good question. Administrative distance is always localā€¦itā€™s never shared between routers.

Rene

12

Ok, that makes sense, I have GNS3 and thatā€™s what I was seeing. Just to add to that, I presume that is the same for all internal ADs, unless its being redistributed into another routing protocol?

13

Hi David,

Yes this applies to all ADs, itā€™s always a local value and never exchanged between router. Even when you do redistribution, AD is never exchanged. The router uses its own list of ADs (that you can change).

Hope that helps!

Rene

14

thanks for the quick replies. As my studying has progressed Ive noticed there are so many ways to redirect the traffic and it seems there is not just one definitive way of resolving an issue, which it cool because it gives the ā€˜programmerā€™ some creativity in achieving a solution.

15

Hi David,

You are welcome. There are quite some methods to change traffic patternsā€¦changing the metric, AD, policy-based routing, distribute-lists, offset-lists and so on.

Rene

16

Rene is there a way to change the External AD of EIGRP by specific? not the whole external, but only some specific EX Routes?

17

i tried the

distance 150 12.0.0.1 0.0.0.0 1

where access list 1 is ā€œpermit host 10.1.1.1ā€

12.0.0.1 is my source ip where i get EIGRP EX routes. the EX AD is still 170. its not changing

18

Hi John,

Iā€™ve seen this problem before, for some reason it doesnā€™t work on EIGRP external routes. I just tried it again myself:

router eigrp 1
distance 80 192.168.12.1 0.0.0.0 1

access-list 1 permit 1.1.1.0 0.0.0.255

Where 192.168.12.1 is the address of the network and 1.1.10/24 is the network Iā€™m trying to change. When itā€™s an EIGRP internal route it works right away, external it doesnā€™tā€¦

The only other option is using the ā€œeigrp distanceā€ command for all external routes I think.

Rene

19

Hi John,

I think there isnā€™tā€¦

Rene

20

Thanks. It seems there isnā€™t. Tried googling it and i cant find some answers

Anyway thanks rene