[Asterisk-Users] QoS What to do?

[Siggi Langauf]

On Mon, 27 Oct 2003, Perry E. Metzger wrote:

> If your DSL link is the bottleneck, rather than earlier hops back
> through the providers network, the provider could also prioritize VOIP
> packets going up the DSL line. That requires a cooperating provider,
> of course.

Not strictly.
Other TCP traffic can also be throttled without anybody's cooperation, by
just delaying ACK packets if you need more bandwith.
Many Linux based router projects (fli4l[1] provides this as a
turnkey option) support QoS by means of reserving bandwidth this way.
In practice, this works fine, unless you're flooded with UDP traffic or
flood pinged (end even in those cases, an occasional ICMP Source Quench
message may help, if you don't have a totally evil provider that drops
ICMP altogether).
Unfortunately, this requires quite some configuration on the router,
but it allows you to experience no noticeable VoIP dropouts even though
your bandwidth is completely (well, ~90%) saturated with P2P traffic...

[1] www.fli4l.de (English translation is a bit neglected, though)