[nsp] cannot burst the line

[dave o'leary]

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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>>--
>>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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