From: Darby Weaver (ccie.weaver@gmail.com)
Date: Mon Dec 01 2008 - 19:36:15 ARST
Then the answer of the question would be that the priority command
effectively carves out a chunk of bandwidth for the class in question.
This means if you have 7Mbps to Voice and were using the priority command to
police the traffic, then congested or not, this is the amount of traffic
Voice would be limited to. No matter the bandwidth of the link or the state
of link with regard to congestion.
On Mon, Dec 1, 2008 at 3:40 PM, shank shank <shankshink@yahoo.com> wrote:
> i guess what i was trying to understad that is when the priority command is
> applied to certain calss can we think of this as a way to limit the
> bandwidth
> to that class to whatever bandwidth configured. i thnk this what anthony
> confirmed. or is it conditioned on the congestion status of the interface?
> ________________________________
> From: Scott M Vermillion
> <scott_ccie_list@it-ag.com>
> To: paul cosgrove <paul.cosgrove@gmail.com>
> Cc:
> Anthony Sequeira <asequeira@internetworkexpert.com>; shank shank
> <shankshink@yahoo.com>; CCIE Group <ccielab@groupstudy.com>
> Sent: Monday,
> December 1, 2008 3:00:46 AM
> Subject: RE: Priority command
>
>
>
> > The link
> mentions that "During
> congestion conditions, a priority class cannot use any
> excess bandwidth".
> Perhaps that is what you are thinking of.
>
>
> That s
> precisely what I was thinking of Paul!
> ;-)
>
> Now
> this whole thing gets
> interesting when you really ponder the definition of congestion.
> It s
> tempting to think that 129 kbps of traffic presenting to an
> interface clocked
> at 128 kbps equals/leads to congestion (which it obviously
> does) and leave it
> at that. But congestion actually occurs
> in scenarios where you haven t even
> reached your interface clock
> rate! As I understand things, anyway. For the
> purposes of QoS,
> congestion means that your TxRing is full and has backed up
> into the configured
> SW queue(s). Depending on TxRing s depth and the
> burstiness of the
> traffic, it may well fill quickly (and recall that the very
> act of configuring
> a SW queue on an interface automatically results in its
> TxRing being truncated
> so as to invoke the SW queue more readily).
>
> So
> I
> think if you had an interface running at 100 Mbps and you configured a
> priority class of 10 Mbps, then presented nothing but the priority class of
> traffic to that interface, you d likely see greater than 10 Mbps of
> throughput
> but less than 100 Mbps, depending on the nature of the traffic itself
> (and to
> an extent I can see there being platform-specific and interface
> type-specific
> differences). I would expect the SW queue to be invoked at
> some point, the
> priority-class to be policed, and then the SW queue to be
> released for a
> period, so on and so on
>
> (may
> just be a good lab to put together at some
> point)
>
>
> -----Original Message-----
> From: nobody@groupstudy.com
> [mailto:nobody@groupstudy.com] On Behalf Of
> Anthony Sequeira
> Sent: Sunday,
> November 30, 2008 12:25 PM
> To: shank shank
> Cc: CCIE Group
> Subject: Re:
> Priority command
>
> Yes - the priority command is used with Low Latency Queuing
> (LLQ) and
> it specifies the amount of priority bandwidth to provide to a type
> of
> traffic (typically Voice). This command also causes a POLICING to the
> amount of bandwidth specified..
>
> This is a mechanism to guard against queue
> starvation for other
> traffic forms.
>
> Anthony J. Sequeira, CCIE #15626, CCSI
> #23251
> Senior CCIE Instructor
>
> asequeira@internetworkexpert.com
>
> Internetwork
> Expert, Inc.
> http://www.InternetworkExpert.com <http://www.internetworkexpert.com/>
> Toll Free: 877-224-8987
> Outside
> US: 775-826-4344
>
> On Nov 30, 2008, at 1:33 PM, shank shank wrote:
>
> > hello,
> >
> quick question experts: does the priority command apply a
> > maximum limit when
> specifying a bandwidth? or is it applying the
> > minimum bandwidth certain
> class can get in the policy?
> >
> > so does this command priority 100 means that
> the maximum bandwidth
> > the class will get is 100k?
> >
> >
> > according to this
> link
> http://www.ciscosystems.com/application/pdf/paws/10100/priorityvsbw.pdf
> >
> it does both. can anyone clarify this to me. thanks,
> >
> >
> > Blogs and organic
> groups at http://www.ccie.net
> >
> >
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