[nsp] cannot burst the line

[D]

Used to run into similar issues like this back in the day. Quite frequently.

A very simple way to test some of these issues is to run 2-3 concurent file
transfers.

If one transfer does 220Kb/s, do two transfers fill the pipe to 400+Kb/s?
If it does, then you know its not the network in the middle thats limiting
you.

-D

Darrel Lewis

----- Original Message -----
From: "dave o'leary" <doleary@juniper.net>
To: "Felix Lee" <felixlee_hk@hotmail.com>
Cc: <cisco-nsp@puck.nether.net>
Sent: Friday, September 13, 2002 6:16 AM
Subject: Re: [nsp] cannot burst the line


> At 12:48 AM 9/13/2002 +0000, Felix Lee wrote:
> >Dear all,
> >
> >It is a leased circuit.  It can be bursted up to 500K at day time.  But
> >the file copying cannot only occupy half of the bandwidth.
>
> Without more details, it is difficult to determine what the issue might
> be - similar to the question/discussion posted by Blaz Zupan recently.
>
>   - is there another link/circuit somewhere else in the end to end path
>          that is a bottleneck that would cause either TCP or the
application
>          to throttle back the transfer to 220kb/s?
>
>   - was the TCP window of your system holding the transfer rate to a lower
>          value because of a long delay?  See here for some hints for
>          understanding these issues (although 220 kb/s is really quite
low,
>          there are also some pretty poor TCP implementations still
lingering
>          around out there)
>          http://www.psc.edu/networking/perf_tune.html
>
>   - looking at the switching devices in the path (routers, FR switches,
ATM
>          switches, ethernet switches) - is there some device somewhere
that
>          is tossing packets?  Is it configured to do so or is it seeing
some
>          errors in the packets and hence throwing them away?
>
> I hope this provides some hints but again it is difficult to diagnose
further
> without more information about the network topology and environment.
>
>                                          dave
>
>
> >FL
> >
> >
> >>From: Jared Mauch <jared@puck.nether.net>
> >>To: Felix Lee <felixlee_hk@hotmail.com>
> >>CC: cisco-nsp@puck.nether.net
> >>Subject: Re: [nsp] cannot burst the line
> >>Date: Thu, 12 Sep 2002 10:52:16 -0400
> >>
> >>         is this frame relay?
> >>
> >>         if so, most telcos, etc.. have a 50% CIR (Commited Information
Rate)
> >>that allows you to burst up to 512k at times when there is capacity but
> >>they only commit to giving you 50% of the full link speed.
> >>
> >>         - jared
> >>
> >>On Thu, Sep 12, 2002 at 02:47:12PM +0000, Felix Lee wrote:
> >> >
> >> > Dear all,
> >> >
> >> > I have a 512K link, the link can be bursted to ceiling in day time.
I
> >> have
> >> > scheduled a job to copy around 3GB data from one end to another atthe
> >> night
> >> > time, and which was expected to be completed at around 13 to 14
hours, but
> >> > we have only got half of the volume transferred.  Monitoring by MRTG,
we
> >> > found the utilization of the link is flat at around 220kbps during
file
> >> > copying.  Can someone tell me why I cannot fully utilize the
bandwidth?
> >> > How can I make it?
> >> >
> >> > Thanks in advance.
> >> >
> >> > FL
> >> >
> >> >
> >> > _________________________________________________________________
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> >> >
> >> > _______________________________________________
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> >>
> >>--
> >>Jared Mauch  | pgp key available via finger from jared@puck.nether.net
> >>clue++;      | http://puck.nether.net/~jared/  My statements are only
mine.
> >
> >
> >
> >
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