OSPF and EIGRP

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Feb 18th, 2008

I have a lab setup for both eigrp and ospf. Attached is my network diagram. When using ospf it appears that it is interface aware even if the interface is not part of the network statement. If I try the same thing with EIGRP and shut down my S0/0/0 interface it seems not to care about any other interface beside the network statement that it is in. Is this a default behavior?

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Edison Ortiz Mon, 02/18/2008 - 11:58

> When using ospf it appears that it is interface aware even if the

> interface is not part of the network statement.

I don't understand this statement, can you expand on this including the commands you are entering and the expected behavior ?

> If I try the same thing with EIGRP and shut down my S0/0/0 interface it seems not to care about any other interface

> beside the network statement that it is in. Is this a default behavior?

Same here, please

___

Edison.

smitty6504 Tue, 02/19/2008 - 05:15

Attached in this post is my config for OSPF. These configs are from my test enviroment. Which is the same as my diagram with the excecption of my outside interface numbers.

I am injecting a default route with a lower metric from 3845-R1 and then a default route on 3845-R2 with a higher metric to my ASA, so i have only one route in the routing table. When i shut down the s2/1 on 3845-R1 it removes the default route from my ASA from 3845-R1 and loads the default route from 3845-R2 as my default gateway. This is the reaction i expect.

I wanted to implament EIGRP between the two routers and the ASA. When doing the same procedure with EIGRP it does not remove the route even though i have shutdown interface s2/1. Is there anyway i can create the same behaivor with EIGRP? I will upload the EIGRP configs in my next post.

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Wilson Samuel Tue, 02/19/2008 - 06:25

Hi,

Pretty interesting scenario, could you please paste the sh ip route output from both situations along with sh ip ospf, sh ip eigrp topo and sh ip route.

Kind Regards,

Wilson sAmuel

bvsnarayana03 Tue, 02/19/2008 - 07:07

are you sure eigrp is running on ASA. I know that PIX/ASA doesnt support EIGRP till version 8.0.

This may be the reason ASA is learning routes exactly when ospf is run, while abnormal behaviour with EIGRP.

smitty6504 Tue, 02/19/2008 - 07:23

I know that is not supported till version 8.0 and later. I am using a router to simulate the ASA right now in my test enviroment.

shivlu jain Tue, 02/19/2008 - 10:55

Smitty

What i understands from your words is that you want automatic removal of the route, please correct me if i were worng. As i think we can do this with the eigrp you can make a policy in which you can map the another interface of router as soon as the interface is reachable the route will be shown in the routing table, as soon as the interface will down the route is not accessible by the router-map and it will get it out form the routing table.

Why i suggest the route-map because according to routing sequence route-map statements will be checked first.

regards

shivlu

smitty6504 Tue, 02/19/2008 - 11:17

That is what i would like to do. My next question is:

Would it be worth making the change for the faster convergance time?

shivlu jain Tue, 02/19/2008 - 11:50

yeah it works well. I had tested in my lab but the scenarios is different but i need the same you are looking for.

Instead of eigrp i played with ospf

regards

shivlu

Mohamed Sobair Tue, 02/19/2008 - 11:46

Hi,

I didnt see any serial interfaces in your design. However , if you want to acheive the same u can do by redistributing static-default route into Eigrp. u could do the same setup which has been done, make sure the (Bandwidth or Delay) from one router is higher than the other one so it will prefer ur desired.

This is acheived when configuring the seed metric (Redistributed route in Eigrp).

HTH

Mohamed

smitty6504 Tue, 02/19/2008 - 11:50

My EGP is BGP so i'm hoping that the ISP will include a default route in the eBGP from the routing table, so i would not like to add a static default route on the 3845's I do have the bandwidth set higher on one 3845 and lower on the other 3845.

shivlu jain Tue, 02/19/2008 - 11:54

yeah this can work. But why not use try PBR, as far my knwoledge is concerned its a good and optimum solution

regards

shivlu

Mohamed Sobair Tue, 02/19/2008 - 12:04

Hi,

u can creat a static default-route pointing to null0 interface with higher AD than the BGP, and then you can redistribute it into EIGRP.

The above shouldnt affect your Network

royalblues Wed, 02/20/2008 - 00:12

The issue you are facing is due to the summary address ip summary-address eigrp 1 0.0.0.0 0.0.0.0 configured on the interface towards the ASA.

Once you configure this, eigrp installs a null0 route to 0.0.0.0 which never gets removed from the RT.

So as suggested above the best way would be to redistribute BGP in eigrp something like this

access-list 1 permit 0.0.0.0

route-map test permit 10

match ip address 1

router eigrp 1

redistribute bgp 200 route-map test

network x.x.x.x

default-metric 10000 10 255 1 1500

no auto-summary

HTH

Narayan

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