From: Scott Morris (swm@emanon.com)
Date: Sun Jan 15 2006 - 11:34:41 GMT-3
Telco = 1000
Data = 1024
A T1 is fun... Each superframe consists of 193 bits. There are 24 channels
in a T1 * 8 bits per sample. 24*8=192. There's an extra bit for framing.
There are 8000 superframes per second. 8000 * 192 USABLE bits = 1.536M.
8000 * 193 ACTUAL bits = 1.544M.
You'll find different equipment references things differently. But that
extra 8000 bits per second aren't actually able to be used by a data stream.
HTH,
Scott
PS. The default on an interface is 1544K. I wouldn't both changing that.
It's viewed as one of those "nobody really cares" things. And the full T-1
is really the only place where calculations seem to be off. A single
channel at 64000bps really IS accurate.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Peter McCreesh
Sent: Sunday, January 15, 2006 7:21 AM
To: InderpalS@mindscapeit.com
Cc: ccielab@groupstudy.com
Subject: Re: Bandwidth on interface
Can't answer that one.
Maybe someone else out there has an answer.
On 1/15/06, InderpalS@mindscapeit.com <InderpalS@mindscapeit.com> wrote:
>
> Ahhh.....another doubt now....T1 = 1536 or 1544??
>
> similarly 1mb = 1024k or 1000k??
>
> I have seen 1000k and 1536k used in many examples...
>
> ------------------------------
> *From:* Peter McCreesh [mailto:petermccreesh@gmail.com]
> *Sent:* Sunday, January 15, 2006 3:41 PM
> *To:* InderpalS@mindscapeit.com
> *Cc:* ccielab@groupstudy.com
> *Subject:* Re: Bandwidth on interface
>
> I see what you mean.
>
> It'll probably work as the default should be 1544K as you have said
> but might be one of those for the proctor to clarify I guess.
>
>
> On 1/15/06, InderpalS@mindscapeit.com <InderpalS@mindscapeit.com > wrote:
> >
> > Well said Pete but now the point is what is the best practice in
> > terms of ccie lab? If asked to guarantee 256k bandwidth for a class
> > and
physical
> > interface speed is T1, will it make any difference if bandwidth is
> > not
set
> > on interface?
> >
> > ------------------------------
> > *From:* Peter McCreesh [mailto:petermccreesh@gmail.com]
> > *Sent:* Sunday, January 15, 2006 3:19 PM
> > *To:* InderpalS@mindscapeit.com
> > *Cc:* ccielab@groupstudy.com
> > *Subject:* Re: Bandwidth on interface
> >
> > I think it determines what is available from the BW command on the
> > interface and if this is, say, 64K and you set a policy to apply
> > 128K to
a
> > class, it won't let you as it will give the following error message
> > (if
the
> > class-default is assigned 128k and applied to int s0/1):
> >
> > I/f Serial0/1 class class-default requested bandwidth 128 (kbps),
> > available only 48 (kbps)
> >
> > So the BW needs to be correctly set (or at least set above what you
> > need) as far as I can see but i am open to correction on this.
> >
> > Regards,
> >
> > Pete
> >
> >
> > On 1/15/06, InderpalS@mindscapeit.com < InderpalS@mindscapeit.com >
> > wrote:
> > >
> > > I know that default is 75% minus (bandwidth for priority
> > > queues) but if bandwidth value is given in kbps under policy map
> > > how
does it
> > > help router to set bandwidth value under interface?
> > >
> > > ------------------------------
> > > *From:* Peter McCreesh [mailto:petermccreesh@gmail.com]
> > > *Sent: *Sunday, January 15, 2006 2:58 PM
> > > *To:* InderpalS@mindscapeit.com
> > > *Cc:* ccielab@groupstudy.com
> > > *Subject:* Re: Bandwidth on interface
> > >
> > > Hi Inder,
> > >
> > > The fact that by default CBWFQ only uses 75% of available BW, this
> > > may affect the amount you can assign to each class.
> > >
> > > Other than that, i'm not sure.
> > >
> > > Regards,
> > >
> > > Pete
> > >
> > >
> > > On 1/15/06, InderpalS@mindscapeit.com < InderpalS@mindscapeit.com
> > > >
> > > wrote:
> > > >
> > > > Hi Group,
> > > >
> > > >
> > > >
> > > > When using CBWFQ, it is necessary to set interface bandwidth?
> > > >
> > > >
> > > >
> > > > Scenario 1---------> I guarantee bandwidth for a class using
> > > > Bandwidth ( )kbps command in policy map
> > > >
> > > >
> > > >
> > > > Policy-map policy1
> > > >
> > > > Class class1
> > > >
> > > > Bandwidth 256
> > > >
> > > >
> > > >
> > > > If we still need to set bandwidth on interface then why since we
> > > > are giving guaranteed bandwidth value in policy map.
> > > >
> > > >
> > > >
> > > > Scenario 2---------> I reserve bandwidth for a class using
> > > > bandwidth percent command in policy map
> > > >
> > > >
> > > >
> > > > Policy-map policy1
> > > >
> > > > Class class1
> > > >
> > > > Bandwidth percent 25
> > > >
> > > >
> > > >
> > > > I understand in this scenario, interface bandwidth needs to be
> > > > set so that router can calculate available bandwidth and assign
> > > > to class.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Any inputs are appreciated!
> > > >
> > > >
> > > >
> > > > Regards,
> > > >
> > > > Inder
> > > >
> > > > 1/15/2006 10:55:46 AM
> > > >
> > > > Disclaimer
> > > >
> > > >
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