From: Djerk Geurts (djerk@djerk.nl)
Date: Fri Jul 13 2007 - 08:23:33 ART
Carlos,
> Djerk,
> this is exactly what I was saying, so we agree.
> (Nobody remembers custom queueing ???)
Correct. Nobody _wants_ to remember custom queueing... ;)
> I don't understand the PQ(LLQ) thing you are bringing up though.
> PQs have priority, which is a police statement. They get ALL the
> bandwidth, even first thing (PQ, right?) but up to this much.
> AFAIK, a queue becomes a PQ when you use the priority keyword,
> and this implies the policing of it, so there is no way you can
> have a PQ w/o policing.
Apparently this is not true, CCO doesn't help here as there are too many
conflicting docs on QoS there.
One has to distingush here between software (up to 7200) and hardware (7300
GSR CRS-1) based platforms. The priority key-word, like you say, enables the
priority queue. However the word strict has come to mean (to me at least) a
policed PQ. The confusion is that a priority statement with bandwidth %
isn't a policed PQ, resulting in 'unpredictable' behaviour when shaping VoIP
traffic. So does this mean it is a strict PQ? I recall something from
Networkers this year that best practice is to use the priority keyword with
a police statement and not use the bandwidth option on the priority
statement.
So please correct me if I'm wrong Cannes was back in January after all and
I've not had the time since to look it up in my notes or hand-outs. Btw, I
don't trust CCO anymore on the subject of QoS...
I understand that things may be different from what they said at Networkers
to what we study for the lab. Networkers referred to the CRS-1 mostly (due
to marketing?) while the lab uses only SW based routers.
> The whole thing I was trying to say is that the default queue
> works like a "low priority" queue, but without the grace of
> the policing of the rest, and thus the starving possibility.
> (when no bandwidth is assigned)
I agree totally
> BTW, queues don't need to know their bit rates, just their "share"
> of available BW. In your examples, 3/4/3 or 1/5/4.
And again 100% correct
> -Carlos
Djerk
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