On Apr 10, 2009, at 12:48 PM, Henning Schulzrinne wrote:
As part of a research project, we are working on automated
diagnostics of network-related faults in residential, SOHO,
conference/special event, hotel and similar networks. If you have
observed errors that were hard for a lay person to diagnose, whether
due to end system problems, NATs, LAN or Internet issues, please
send me a brief description. (Also, contacts in tech support for
I'm not sure if this is the kind of fault you're looking for. In
residential networks, often the DSL or Cable "modem" has a misfeature
that caches the MAC address of the first device it sees, and won't
talk to any others. Often it will only forget the cached MAC address
if it's been powered off for a significant time (15 minutes, or an hour).
When the ISP's tech sets up a new home, sometimes they come with
Windows based software. If the customer doesn't use Windows, the tech
will connect their own laptop to run the setup software. Or, the ISP
person wants to connect directly rather than through the wireless
router. Then the customer tries to use it and it doesn't work, but
since the ISP's tech had no problems and reported the Internet
connection working, they blame the customer's computer or wireless
router.
In my experience, I've found that ISP setup people rarely know about
this, and often don't understand what "caching the MAC address" means
even if you try to explain it to them, to ask if their equipment does
it. I think a lot of customers who experience this never figure it
out before the problem mysteriously disappears eventually, when they
happen to have the thing powered off for a while because they thought
it wasn't working.
I've also encountered this at other people's homes, where they don't
have wireless, and one person's computer gets Internet but the other's
doesn't most of the times they try - I've "solved" this problem for
other people several times, merely by explaining that they have to
power off the dsl/cable box for a certain number of minutes when
switching computers (they can figure out how long by experimenting),
or by connecting one laptop and sharing its connection to the other
via wireless.
-- Cos
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