EIGRP Question

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Jun 6th, 2008
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Between two routers I have 2 E1 links.I am running eigrp want to make 1st link primary and 2nd link secondary, what i want to achieve my all traffic should move over 1st link a) wherever this link is fully utalized traffic should move on 2nd link also .b) whenever 1st link performance is degraded or relibility goes down then traffic should always move over secondary link.


Please let me know if its possible.

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Richard Burts Fri, 06/06/2008 - 07:37
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ajay


While EIGRP certainly allows you to configure so that there is a primary link and a backup link, EIGRP does not provide the ability to shift traffic between links based on the load of the primary or based on degraded performance of the primary.


While I have not used it and can not speak from experience, I understand that using OER may allow you to do something like this.


HTH


Rick

ajay chauhan Fri, 06/06/2008 - 07:45
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Hi Rick,


Can u please explain me how to configure OER in this scenario pls .



Giuseppe Larosa Mon, 06/09/2008 - 09:11
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Hello Rick,

by changing the k-values inside the eigrp process you could take in account the load in the EIGRP metrics calculation.

However, I'm afraid it could lead to some instabilities if it is too fast in reacting to changing load values.

I agree OER could be a better safer solution but I haven't direct experience too.


Best regards

Giuseppe

ruwhite Tue, 06/10/2008 - 03:40
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EIGRP doesn't read the metrics off the interface dynamically, so this won't work for the moment. The metrics are only read at the time the interface is brought up.


Dynamically reading metrics are planned, but not available/documented right now.


:-)


Russ

Giuseppe Larosa Tue, 06/10/2008 - 06:02
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Hello Russ,

this is something I didn't know I thought EIGRP was able to read the interface load parameters from time to time.

If this is not true the load part of the EIGRP metrics is useless at the moment.


I understand that reading the interface parameters will lead to an increase in cpu usage and can lead to an increased frequency in eigrp topology changes and recalculations


Best Regards

Giuseppe

ajay chauhan Tue, 06/10/2008 - 06:21
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this is also something which i am also not aware about I have always seen in eigrp running enviroment if we change the bw,delay if recalculates the metric automatically we don't need to reset the eigrp to recalculate the changes .

Richard Burts Tue, 06/10/2008 - 08:56
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ajay


You are not talking about the same things that Russ is, so what he says (about the load parameter) does not apply to your comment about bw and delay.


You are right that if you change bw or delay then EIGRP should pick up that change and recalculate its metric. But Russ is right that EIGRP looks at the load when it initially calculates the metric and does not look back to see if load has changed.


HTH


Rick

ruwhite Tue, 07/01/2008 - 05:15
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"You are right that if you change bw or delay then EIGRP should pick up that change and recalculate its metric"


This is because these are manual configurations on the interface.... When you change the bandwidth or delay on the interface, EIGRP resets the neighbor adjacencies on that interface so it can pick up the changes. If you do a log-neighbor-changes, you should see the reset.


In more recent code, we will do a soft reset, or rather a graceful restart, rather than a hard reset. When the neighbor's reset, we will also pick up the load, utilization, and other parameters.


:-)


Russ

shiva_ial Fri, 06/06/2008 - 08:48
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hi,

you may also use HSRP TRACKING FEATURE if you topology suits with it.


rgds/shiva

ajay chauhan Fri, 06/06/2008 - 08:50
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Shiva,


I have only single route each end .

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