Internetworkers: http://www.ibiblio.org/internetworkers/

[Steven Champeon <schampeo AT hesketh.com>]

on Fri, Jan 27, 2006 at 03:10:12PM -0500, Jim Ray wrote:
> your environment may differ from mine.  i live near ncsu and have 26,000 
> students with wireless this, that and the other thing.  from a strict 
> engineering perspective, signal interference is more culprit than 
> anything and has little to do with one's skill in setting up wireless 
> networks.  if signal interference occurs while using a web browser, the 
> end user probably will not notice a problem.  if signal interference 
> occurs while checking email, a POP lock may occur and cause the user to 
> experience a problem.

POP locks occur as a result of only three things: when a user attempts
to check the same POP mailbox from two different locations, or using two
different processes at the same location, or if the POP server exits
very abnormally, leaving a lock file around. It has nothing to do with
what technology they're using to pass the packets back and forth. I've
had to deal with locks when my clients and employees have forgotten to
turn off their home mail client when they come into work, or when they
are checking their mail with both a blackberry and Outlook, etc.

To be specific, every time you check POP mail, the pop server creates a
lock file, where it stores the current contents of the mailbox being
checked, so that incoming mail may be stored in the spool file and then
any pre-existing, undeleted mail messages may be re-integrated into the
spool when the user has completed checking their mail. When said user
tries to check the spool file while they are already checking it using
another process, the POP server responds with an error to the effect
that it already found a lock file, and is refusing to clobber it.

While I agree that signal interference or quality, or channel conflicts,
might be the cause of a dropped POP connection, which might result in a
hung POP process, it's the POP server's fault if it doesn't properly
clean up after itself after a reasonable interval. The same is true of
any sort of TCP connection - network latency happens, it's not unique to
wireless.

Anyway, WRT whether wireless alone is sufficient for a small office is
really a matter of what kind of bandwidth you need; if your employees
are used to an unswitched 10Mb/s ethernet connection, they won't feel
much difference using 802.11b, though it will be a bit slower. If your
environment isn't saturated with other wireless networks, it's probably
fine as a stopgap. We use a mix of wireless (b and g) and cat 5e 100Mb/s
switched ethernet here, because some of us sling around huge Photoshop
files and the like. All depends on your mix.

HTH,
Steve

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