On Feb 12, 2007, at 9:10 AM, <michael.dillon@bt.com> <michael.dillon@bt.com> wrote:
They are used for BUSINESS traffic. Also, since these controls make routers work harder, there is no point in using them where there are no traffic problems.
I concur, it only matters when it matters (i.e., when there's resource contention).
Most providers build their core networks with enough headroom so that there are no traffic problems.
It's not a matter of just forwarding capacity, it's a matter of control plane processing capacity, a variable typically orders of magnitude less than the the former.
And the fundamental problem of QOS means that you only use it where you have to. QOS works by delaying or discarding packets. It is hard to sell that as a valuable service to ordinary users.
I believe Christos's query wasn't about ordinary users or transit traffic, it was regarding "control (e.g., routing) traffic". I wouldn't consider network operations or control traffic "ordinary users" and suspect that if network operators aren't limiting "what" and at what rate that "what" is permitted to impact the control plane then their ordinary users should be very concerned. A usual example of this is DDOS attacks much larger than 10 Gbps sustained, throwing bandwidth at the problem yields little or no return. -danny