VoIP QOS best practices

Mon Feb 10 22:51:23 UTC 2003

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

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