From: Dan (dans@danshtr.hn.org)
Date: Fri Dec 17 2004 - 04:23:48 GMT-3
So the later method actual cir is always = BC+be , and you can also color
bc and be differently
On Thu, 16 Dec 2004 16:37:26 -0500, Bob Sinclair
<bsinclair@netmasterclass.net> wrote:
> Tim,
>
> Thanks for the reference regarding Odom's new book! Have you seen
> Szigeti's
> new book, End-to-End QoS Network Design, ISBN: 1-58705-176-1? It has
> less
> depth on individual tools, but provides needed, up-to-date context. He
> compares the single-rate and two-rate three-color markers.
>
> The practical advantage to the two-bucket, 3-color markers is that you
> have
> three actions available: conform, exceed and violate. The Bc bucket is
> the
> dividing line between conform and exceed (in-profile, out-of-profile).
> The Be
> bucket is the dividing line between exceed and violate
> (a-little-out-of-profile vs. way-out-of-profile). You might transmit
> traffic
> that conforms, mark down traffic that exceeds and drop traffic that
> violates.
> So, have three colors (two buckets) allows you to break traffic down more
> finely.
>
> Once you decide you want three colors (conform, exceed, violate), you
> can then
> choose between the singe-rate and two-rate methods of filling the second
> bucket (Be). In the single-rate method tokens can only go into the Be
> bucket
> if they have been saved (you were below CIR for a while). If one is
> paid $10
> per week one can burst to $15 only by saving. In the two-rate method,
> tokens
> are placed into the second bucket independent of saving from CIR. If
> you have
> a job paying $10 per week, and a second job paying $5 per week, these
> are two
> independent rates, and one can burst to $15 per week without having to
> save.
> Szigeti says the latter method leads to more predictable bursts.
>
> As regards the utility of the shape peak command, I am with you, and do
> not
> see it.
>
> HTH,
>
> Bob Sinclair
> CCIE #10427, CCSI 30427, CISSP
> www.netmasterclass.net
>
> ----- Original Message -----
> From: ccie2be
> To: Bob Sinclair
> Cc: Group Study
> Sent: Thursday, December 16, 2004 3:35 PM
> Subject: Re: Shape peak and police pir
>
>
> Hi Bob,
>
> Yes, They changed the name of the book from DQoS to just QOS. ISBN
> 1-58720-124-0.
>
> Getting back to peak rate, I might be a bit thick skulled on this, but
> what's the application of enforcing a peak rate separate from the cir? I
> feel
> I'm missing the big picture with this.
>
> For example, let's say you're pre-sales technical support and you're
> talking
> to the buyer of ISP services for a mid-size firm and this buyer, as luck
> should have it, doesn't know squat about traffic engineering or bc, be
> or Tc.
> But, he does know that his firm likes to sell lots of widgets over the
> internet and that if visitors to his web site find that response time is
> too
> slow, they leave his web site and buy from someone else. He also knows
> that
> his web site (which he created mostly by himself) has some nifty pages
> that
> contain some large graphic files.
>
> Also, occasionally, his firm runs specials which generate lots of
> traffic to
> his site, but as you would expect, he also wants to minimize his monthly
> web
> traffic expense while insuring his customers have a good web experience.
>
> How would you help him decide whether it would be better for him to
> sign up
> for cir with be service or your combo cir and pir service?
>
> Also, do you have any comments on the shape cir versus shape peak
> issue?
>
> TIA, Tim
>
>
> ----- Original Message -----
> From: Bob Sinclair
> To: ccie2be
> Sent: Thursday, December 16, 2004 2:52 PM
> Subject: Re: Shape peak and police pir
>
>
> Hi Tim,
>
> Are you referring a new edition of Cisco DQOS by Wendell Odom? I
> don't
> see one at ciscopress.com. Could you post the ISBN?
>
> Re policing with CIR/PIR: If you want a three-color marker (conform,
> exceed, violate), then you can you can use either method (single rate or
> two-rate). The RFCs (2697 and 2698) say that the single-rate is most
> useful
> when it is the LENGTH of a burst, not its peak rate that determines
> service
> eligibility. The two-rate is most useful when peak rate needs to be
> enforced
> separately from a committed rate. The two-rate method allows for a
> sustained
> excess rate, and seems easier to configure, to me, but it really depends
> on
> the traffic profile you want to enforce.
>
> HTH,
>
>
> Bob Sinclair
> CCIE #10427, CCSI 30427, CISSP
> www.netmasterclass.net
>
>
> ----- Original Message -----
> From: "ccie2be" <ccie2be@nyc.rr.com>
> To: "Group Study" <ccielab@groupstudy.com>
> Sent: Thursday, December 16, 2004 2:15 PM
> Subject: Shape peak and police pir
>
>
> > Hi guys,
> >
> > I've been going through the 2nd Edition of Cisco QOS and overall
> it's a
> very
> > good book. It fills some of the gaps that weren't covered in the
> first
> > edition and is as you'd expect more up-to-date.
> >
> > I just finished going over shaping and policing for the umpteenth
> time,
> but
> > I'm still a bit fuzzy on the above commands.
> >
> > I understand the syntax and mechanics of the above commands, but I
> don't
> get
> > the point of these commands.
> >
> > What I mean is why use shape peak instead of shape average with
> different
> > values? With shape peak, (bc + be) are aent every Tc. If bc
> + be = X,
> why
> > not just use shape average X instead? What's the difference?
> >
> >
> > For police pir, I have similar question: what's the practical
> benefit
> of
> > having 2 rates? Can't the same result be achieved, for example,
> by an
> ISP, by
> > charging one rate for packets (or bytes) that conform and and
> higher
> rate for
> > packets that exceed?
> >
> > Thanks, Tim
> >
> >
> _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
-- Best Regards, DanUsing Opera's revolutionary e-mail client: http://www.opera.com/m2/
This archive was generated by hypermail 2.1.4 : Mon Jan 03 2005 - 10:31:27 GMT-3