IP CEF load balancing

royalblues · ‎07-24-2006

Hi,

I am slightly confused with the default load balancing method used by CEF (Per Destination load balancing).

I have 2 links and i would like to know how the router decides to use the links for a flow.

I have been having trouble with 2 links which are load balancing on per destination CEF. I see around 90 % utilization in the 1st pipe and only 70% on the second. Because of this the latency on the first pipe shoots up drastically causing applications to hang. AT all these times the 2nd pipe latency is always normal.

I Would like to know whether some fine tuning is required for CEF per destination to work properly.

Richard Burts · ‎07-24-2006

Narayan

With per-destination load sharing (or load balancing) whether it is with CEF or the older fast switching you may likely get some difference on the individual links. This is because some destinations are likely to get more traffic and some destinations will get less traffic. While this type of load share is pretty close it will not be exact. Note that even if you do per packet load share the load may not be exactly even because there could be larger packets on one link and smaller packets on the other link (and per packet balancing does introduce the probability of out of order packets).

If you want really equal distribution of traffic over the links then you should probably consider putting both serial links into a multilink PPP configuration. MLPPP will give you even distribution of traffic on both links.

HTH

Rick

HTH

Rick

jackyoung · ‎07-24-2006

Per-destination load-sharing always not able load-share at equal bandwidth. If you find there is better line condition at second link, why not make the critical application to travel at second link as primary link ?

I suggest to use load-sharing on same condition links.

My 2 cents.

abhishek_nandavat · ‎07-25-2006

Hi,

Maybe the following link can help. Have a look!

http://www.cisco.com/en/US/tech/tk827/tk831/technologies_tech_note09186a0080094806.shtml#knowniss

Hope it helps.

Regards,

AbhisheK

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