[114405] in North American Network Operators' Group
Re: PPP multilink help
daemon@ATHENA.MIT.EDU (Anton Kapela)
Mon May 11 12:04:23 2009
In-Reply-To: <4A083C25.10809@olp.net>
Date: Mon, 11 May 2009 12:02:40 -0400
From: Anton Kapela <tkapela@gmail.com>
To: Dan White <dwhite@olp.net>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Gents,
On Mon, May 11, 2009 at 10:54 AM, Dan White <dwhite@olp.net> wrote:
> Andrey Gordon wrote:
[snip]
>> When I transfer a large file over FTP (or CIFS, or anything else), I'd
>> expect it to max out either one or both T1, but instead utilization on the
>> T1s is hoovering at 70% on both and sometimes MLPPP link utilization even
>> drops below 50%. What am I'm not gettting here?
Sounds like the TCP window is either set 'small' or TCP window scaling
either isn't enabled or isn't scaling to your bandwidth/delay product
(for the hosts in question). Since FTP is a 'stream' based transport
of file data (like http), you should see this scale to nearly all of
or most of your links (assuming TCP isn't your issue).
Additionally, when using CIFS, SMB, TFTP, NFS, and other
command->acknowledgment style protocols over wide-area links (which
aren't stream-based operations, but rather iterative operations on
blocks or parts of a file), you likely will never observe a single
transfer filling up the links.
-Tk
