From: Eric Phillips (ephillips@squick.cc)
Date: Thu Oct 18 2007 - 22:36:56 ART
I love labbing things up, that is the best way I learn. But I am not quite
sure how to test this one though. I could test if the packet is dropped,
but I can't think of any way to test something like what Joel said, where
future Tcs are "shorted" their Bcs.
Something like IGPs we have debugs that we can watch, but this is dealing
with hundredths of a second.
Thanks for your reply Joel, I definitely appreciate it!
-Eric
On 10/18/07, Gregory Gombas <ggombas@gmail.com> wrote:
>
> I didn't mean it literally, I just meant that since the packet will
> always be exceeding bc it can never be sent...and thus dropped.
>
> Only way to know for sure is to lab it up!
>
> On 10/18/07, Eric Phillips <ephillips@squick.cc> wrote:
> > Thanks everyone for the replies, I definitely appreciate it!
> >
> > I did skip a 0 there, sorry... I was aiming for a 10ms Tc to make VOIP
> > traffic delayed as little as possible. So yes, the Bc would be 640
> bits.
> >
> > Herbert, my numbers were referring to Shaping, so I was keeping
> everything
> > in bits. With policing you deal in bytes.
> >
> > I am very intrigued to see that we have three answers, so perhaps I am
> not
> > the only one that is a bit confused by this. If it is queued forever,
> does
> > it block the pipe while it is queued?
> >
> > -Eric
> >
> >
> >
> > On 10/18/07, Gregory Gombas <ggombas@gmail.com> wrote:
> > >
> > > Even with shaping configured, if the router queues the packet then it
> > > would be queued indefinately considering it will always be larger than
> > > bc and never be able to send it...
> > >
> > > On 10/18/07, Herbert Maosa <asawilunda@googlemail.com> wrote:
> > > > Eric,
> > > >
> > > > I assume you are maintaining bytes as the unit for Bc and ms as the
> unit
> > > for
> > > > TC ? In that case Bc of 64 Bytes and Tc of 10ms is giving me CIR =
> > > 512Kbps,
> > > > using the formula CIR = Bc/Tc.
> > > >
> > > > In any case, what will happen to a packet that is larger than the
> > > maximum
> > > > rate permitted will depend on whether you are shaping or policing.
> If
> > > you
> > > > are shaping, then the packet will simply be queued in the shaping
> queue
> > > from
> > > > which it will then be sent at CIR. If you are policing then it will
> > > depend
> > > > on the configured action for non-conforming traffic.
> > > >
> > > > Herbert.
> > > >
> > > >
> > > > On 10/18/07, Eric Phillips <ephillips@squick.cc> wrote:
> > > > >
> > > > > Hi all,
> > > > >
> > > > > I have searched through the GroupStudy archives, read through
> Odem's
> > > DQOS
> > > > > book, and checked out the DOC CD, but have not found a clear
> answer to
> > > a
> > > > > question that has been on my mind.
> > > > >
> > > > > If I enable shaping with a very small Bc, for example, a Tc of 10,
> and
> > > a
> > > > > Bc
> > > > > of 64, that should shape to 64kbit/sec, right? Now if I do not
> enable
> > > > > link
> > > > > fragmentation, and a large packet, perhaps 1400 bytes comes
> through,
> > > what
> > > > > will happen? It can not be sent in a single Tc, and it can not be
> > > > > fragmented because link fragmentation is disabled. Also assume
> that I
> > > > > have
> > > > > no Be, or a Be too small to allow 1400 bytes to accumulate between
> Bc
> > > and
> > > > > Be.
> > > > >
> > > > > This seems like an awfully simple question, but I have not found a
> > > clear
> > > > > answer anywhere.
> > > > >
> > > > > Thank you very much,
> > > > >
> > > > > Eric
> > > > >
> > > > >
> > >
> _______________________________________________________________________
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> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > Kindest regards,
> > > > hm
> > > >
> > > >
> _______________________________________________________________________
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> >
> > _______________________________________________________________________
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