Per packet load balancing and bandwidth utilization

Unanswered Question
Oct 12th, 2009


We have two core routers connected to other two core routers with STM links on 7507 routers.

We have 7 links each on two routers.

We have configured multilink with 14Mb on both routers.

Now we have two more routers at both sides connected to core-routers through switch.

We have configure load-balancing per packet.Now problem we are facing is we are tranfering data from 2-3 servers but link utilization is not increasing beyond 60%.

Load showing is evenly distributed on multilinks but after 60 % utilization load is not getting increased.

How we can utilize full bandwidh.


I have this problem too.
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Paolo Bevilacqua Mon, 10/12/2009 - 11:39

You should not configure per/packet load balancing as it will cause out of order arrival especially on high speed links.

If you circuits are not fully utilized, either there is not enough offered traffic, or there are packets drops or performance issues somewhere.

vaishali.nagpure Mon, 10/12/2009 - 20:39


We want load balance on both links.

If we remove per-packet then it will use per-destination.

Then it is using only one link.As our source and destination server are same and are database servers transfering large amount of data,with per-destination we are not able to utilize both links.


Paolo Bevilacqua Tue, 10/13/2009 - 03:02

First of all, per-destination does not exist anymore, CEF uses per-flow where also both addresses and ports are used in determining the link.

Test yourself and you will find that with per-packet, one same transfer can actually take longer due to out-of-order arrival.


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