Why is my router activity light going nuts?

[kentborg at borg.org (Kent Borg)]

On Sun, Sep 23, 2001 at 08:06:38PM -0400, Duane Morin wrote:
> Lately I've noticed that the activity light on my linksys router is constantly 
> blinking.  We're talking more than once a second, even when I'm not active on 
> the machine.

I noticed something similar a few weeks ago.

I logged onto my basement server and did a tcpdump to watch the
traffic.  It took awhile to figure out what was going on, because the
traffic was broken.

In my case I have my qmail logging translating IP numbers to names,
and it was constantly asking about a long list of addresses.  I saw
new list mail coming in, but DSN lookups were not working.  After
further poking about I noticed that no outgoing connections were
working.  I tried rebooting the server but that didn't fix it.  I
can't remember what got me to try the thing that fixed it: I power
cycled the DSL modem/router/hub and that fixed it.  Oh, and then a day
or so later I rebooted not-yet-ready backup server, it had lost it's
network connection in the confusion too.

NB: I have a different model router.

Lesson: Doing a tcpdump can be informative.  But do it in an emacs
shell so you can easily scroll around in the frequently prodigious
output.  And don't this over a remote login from, say, work, because
that will generate its own network traffic and unless you are clever
about what you don't catch in tcpdump you will get the networked
version of acoustic feedback.


Good luck, let us know what you find,

-kb
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