[c-nsp] Per packet load balancing with low latency applications

[Joe Provo]

On Thu, Jan 15, 2009 at 12:25:18PM +0000, William wrote:
> Hello list,
> 
> I've been looking at using per packet load balancing with a couple of
> serial links to use with a low latency market data application, in all
> the cisco docs they seem to mention how VoIP/Video applications may
> chuck their dummy out with packets arriving out of sequence. My
> question is what would cause the packets to arrive out of sequence?
> And has anyone been in my position before? what was the outcome?

If these are wide-area links, latecy can vary due to grooming or
other re-provisioning.  If they are protected links, expect at some
point during their life to switch ntependently and wind up with 
differing latencies.

> Per packet is going to be used because there will only be one machine
> on each end of the link talking to each other.

Look at link-layer aggregation methods (mlpp for ptp, LAG for ether, 
etc) or getting a bigger pipe instead.  Simple is good.

> Any more information/real life experiences on the matter are welcome.

In my experience, per-packet always kills goodput.


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