From: Chris Larson (clarson52@xxxxxxxx)
Date: Wed Nov 21 2001 - 19:55:12 GMT-3
Also you need to set the bandwidth for proper routing protocol metrics for
some routing protocols. I have alos been told the the load 0/255 or
utlization is based on what you set the bandwidth parameter to. So if you
have a 56k serial line but keep the bandwidth default at 1544 then your
utilization number or load will not be correct.
----- Original Message -----
From: "Albert Lu" <albert_ccie@yahoo.com>
To: <swm@emanon.com>
Cc: <ccielab@groupstudy.com>
Sent: Wednesday, November 21, 2001 3:37 PM
Subject: RE: Simple Question on serial interfaces.
> Scott,
>
> I agree with what you are saying, in the real world you would always know
> what the bandwidth you have is on the link. I'm justing saying in a lab
> environment where you are using alot of back-to-back connections, and your
> serial defaults to T1.
>
> Looking at ISDN, it looks like the link gives you a 64k bandwidth from the
> interface command. However, if you have both channels, don't you get
bumped
> up to 128k?
>
> Albert
>
> -----Original Message-----
> From: Scott Morris [mailto:swm@emanon.com]
> Sent: Wednesday, November 21, 2001 11:53 PM
> To: 'Albert Lu'
> Subject: RE: Simple Question on serial interfaces.
>
>
> ANY time you are doing calculations that need to know real bandwidth..
ie.
> routing protocol metrics, load-sharing stuff, CAR, traffic shaping, RSVP,
> QoS... Any of that stuff that will make calculations based on the
bandwidth
> of the line. Then you need to have REAL bandwidth there.
>
> Imaging a serial interface with a fractional T-1, only 128k configured on
> it. You want to run VoIP, running G.711 (uncompressed). You will need to
> reserve 80k of bandwidth per phone call (64k data + overhead).
>
> Well, like a bad person, you configure your rsvp with no top end
> reservation, figuring that gives you flexibility as you increase your t-1
> speed, so you don't need to reconfigure stuff.
>
> Well, your first call goes through, the router checks bandwidth and says,
> yea, that's cool. Now the second call comes through... According to your
> routers' calculations, you've only reserved 80k out of a 1544k line. So,
> sure, bring it on! Plenty of calls. Reality is both calls will start to
> suck badly.
>
> Use the bandwidth command. It's good design documentation anyway!
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Albert Lu
> Sent: Tuesday, November 20, 2001 10:50 PM
> To: 'Duy Nguyen'; Charles.Conte@NASD.com
> Cc: ccielab@groupstudy.com
> Subject: RE: Simple Question on serial interfaces.
>
>
> On the otherhand, it seems like serial links always default to a T1
> 1.544Mbps for routing protocol cost calculations.
>
> Another question that has been in the back of my mind is that when should
> the bandwidth statement be entered into the interface? From various labs
> (eg. fatkid), and sources they say that it is a good idea to always
include
> the bandwidth statement for all WAN interfaces (FR, Ser, BRI, ATM). But if
> there were no specifications for what bandwidth to put on the interfaces,
> then what can you do?
>
> I guess if the bandwidth statement was left off, then they would default
to
> T1 and that should be ok.
>
> Albert
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Duy Nguyen
> Sent: Wednesday, November 21, 2001 2:02 PM
> To: Charles.Conte@NASD.com
> Cc: ccielab@groupstudy.com
> Subject: Re: Simple Question on serial interfaces.
>
>
> whatever you assign the clockrate, that's your total bandwidth. Try to do
> tftp w/ 128k than try w/ 2048k you will see the difference. clockrate=bw.
>
> Absolutely Positively Continuously Sincerely,
>
>
> Duy Nguyen CCNP/CCIE written
> net_port@hotmail.com
> Cell (817) 707-7451
>
>
>
> >From: "Conte, Charles" <Charles.Conte@NASD.com>
> >Reply-To: "Conte, Charles" <Charles.Conte@NASD.com>
> >To: "'ccielab@groupstudy.com'" <ccielab@groupstudy.com>
> >Subject: Simple Question on serial interfaces.
> >Date: Tue, 20 Nov 2001 20:31:14 -0500
> >
> >All,
> >
> > I have a real stupid question. Anyways to find out what the serial
> >interface clockrate what do I have to do. Can I assume that whatever it
> >assigns as BW is what the clockrate is set at. I don't think this is
true
> >because I configured my IGX to run on the clockrate of 2048. Maybe I
> >missed
> >it when I did the show controller command or show int serial command, but
> >help me out guys.
> >
> >Charles
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