EIGRP Traffic Sharing

[aamer.ali]

Dear All,

I have two links from ISP 6Mb and 2Mb so i want to confiugre load sharing so that 75% of inbound traffic to interet will go from 6Mb link and other 25% traffic will go from 2Mb link..

Regards,

Aamer

[Joseph W. Doherty · Accepted solution]

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Posting

Inbound, from the ISP?  Have you spoken with your ISP?

[cadet alain · Accepted solution]

Hi,

if this is outbound traffic destined to Internet then you must unequal cost load-sharing.

for this you must make the successor/feasible successor  feasible distance ratio=3/1 and use variance so that FD of Feasible successor * variance <= FD of successor.

Regards

Alain

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[Peter Paluch · Accepted solution]

Hi Alain,

Two slight corrections:

1. There is no such thing as FD of Feasible Successor or FD of Successor. There is only a FD of the route itself, which is the lowest known distance since the last time the route went passive.
2. For a worse route through a Feasible Successor to be accepted thanks to variance, the following equation must hold: total metric via Feasible Successor <= total metric via Successor * variance

Best regards,

Peter

[cadet alain]

Hi Peter,

yes you are correct, thanks for correcting me.

Regards

Alain

Don't forget to rate helpful posts.

[Richard Burts · Accepted solution]

My interpretation of what Aamer was indicating focuses on the phrase "traffic to interet" and in that sense it would be from the inside network, inbound to the router, and then forwarded toward the ISP.

As suggested by Alain using EIGRP variance may be a possibility. I have a couple of questions about this:

- is it a single ISP with 2 links or is it 2 ISP and each one has a single link:

- Has the ISP agreed to run EIGRP with you on both links?

I have an alternative that you might consider. Set up the 6 Mb link as primary and the 2 Mb link as backup in case of problems with the primary. And then configure Policy Based Routing to identify some types of traffic and to send these over the 2 Mb link.

HTH

Rick

[Joseph W. Doherty · Accepted solution]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Rick, re-reading the OP, I think you're correct ". . .  inbound traffic to interet . . ." may mean egress from user's router to the Internet.

Aamer, if this is want you meant, if the device supported PfR (especially the PIRO variant if you want it to inject into EIGRP), that would be the optimal way to load balance the egress traffic.

Also, Aamer, realize EIGRP load balancing will direct flows in proportion to unequal costs, it doesn't balance actual loading (as does PfR).  For example, 3 light usage flows could be using the 6 Mbps interface while a single heavy usage flow is saturating the 2 Mbps link.

[paul driver · Accepted solution]

Hello

The easiest way I think of eigrp unequal load balancing is dividing the highest/lowest composite metric of say the two paths you wish to use
(Eigrp has already calculated this metric using the lowest bw +total delay values for them)

Sh ip eigrp topology - will give you these metrics

This value is then applied via the variance command to the eigrp process, And then if applicable apply per-packet load sharing to the necessary interfaces

To test you changes

Sh ip route
Sh ip cef exact-route scr dst (this should show packets being load shared over both links pertaining to the variance value applied)

Res
Paul


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[aamer.ali]

Dear All,

Thanks for your guidance, i will do the below and get back to you.

I will configure EIGRP with unequal load balancing and Variance. I will manually configure bandwidth on both outbound interface.

I have Cisco 2801 with 1 extra HWic Card.

Regards,

Aamer

[Syed Siraj Uddin]

Aamer did you manage to make this work ;) ?

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