VoIP QOS best practices

Mon Feb 10 23:23:15 UTC 2003

On Tue, 11 Feb 2003, Petri Helenius wrote:

> 
> >
> > Reordering per se doesn't affect VoIP at all since RTP has an inherent
> > resync mechanism.
> 
> Most VoIP implementations don´t care about storing out-of-order packets
> because they think that 20ms or 30ms late packets should be thrown
> away in any case.
> >
> > Reordering is also unlikely, since each packet is sent 20ms or more apart;
> > I'm not aware of any network devices that reorder on that scale.
> >
> Most "core" routers, at least from vendors C and J have enough packet
> memory to keep packets for hundreds of milliseconds. Apply sufficent

Really.. including many Gigabit, OC-12,48 interfaces

> per packet load balancing (which would be stupid but doable) to this,
> and you´ll arrive at the end result.

And its unlikely you will be doing this therefore..

> 
> Our observations tell us that reordering does not happen too much but
> there are periods from a few minutes to an hour where reordering from
> specific AS´s skyrocket to return to normal, in many cases even without
> observable path change. (MPLS in action?)
> 
> Pete
> 
> 