From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Fri Oct 19 2007 - 20:44:42 ART
You can set the ping timeout to 0 and the router will generate the pings
as fast as it can without waiting for a reply.
ping 10.1.1.1 timeout 0
Brian Dennis, CCIE4 #2210 (R&S/ISP-Dial/Security/SP)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
>----- Original Message -----
Subject: Re: Effect of shaping with small Bc, no fragmentation, and a
large packet?
Date: Fri, October 19, 2007 10:10
From: "Gregory Gombas" <ggombas@gmail.com>
> Hi Andrew,
>
> I'm not sure ping test is adequate since the router waits for a reply
> before sending the next packet...I think you need a UDP application to
> send packets at a fixed rate with specified packet size to really test
> it....
>
>
> On 10/19/07, Usankin, Andrew <Andrew.Usankin@twtelecom.com> wrote:
> >
> > Very good question indeed. I used to thing that packet will go through
> > but now I'm going to dig dipper to make double sure it is.
> > For now, here is what I got from labbing:
> >
> > R1#sh run int s1/0
> > Building configuration...
> >
> > Current configuration : 129 bytes
> > !
> > interface Serial1/0
> > ip address 172.16.1.1 255.255.255.0
> > serial restart-delay 0
> > traffic-shape rate 32000 3200 3200 1000
> > end
> >
> > R1#sh traffic-shape s1/0
> >
> > Interface Se1/0
> > Access Target Byte Sustain Excess Interval Increment
> > Adapt
> > VC List Rate Limit bits/int bits/int (ms) (bytes)
> > Active
> > - 32000 800 3200 3200 100 400 -
> > R1#ping 172.16.1.2 size 1500
> >
> > Type escape sequence to abort.
> > Sending 5, 1500-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
> > !!!!!
> > Success rate is 100 percent (5/5), round-trip min/avg/max = 12/282/412
> > ms
> > R1#
> >
> >
> > As you can see, bytes limit per interval is 800 and I'm sending packets
> > of 1500+24 bites size. They all make it through.
> > Andrew
> >
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Gregory Gombas
> > Sent: Thursday, October 18, 2007 7:27 PM
> > To: Eric Phillips
> > Cc: ccielab@groupstudy.com
> > Subject: Re: Effect of shaping with small Bc, no fragmentation, and a
> > large packet?
> >
> > 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
> > > > > >
> > > > > >
> > > > ____________________________________________________________________
> > > > ___
> > > > > > Subscription information may be found at:
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> > > > >
> > > > >
> > > > > --
> > > > > Kindest regards,
> > > > > hm
> > > > >
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