[BC] IP Weirdness

[Jason R.]

Here's an IP oddity I saw for the first time  -
(sorry for the length, but I'm trying to accurately describe the problem).

  Have you ever seen a machine try to ping a different address than what you 
put in...?

   I have four XP Pro machines tied together with TCP/IP - UDP across a 
small 8 port Linksys Gig ready switch/router. As far as I know, that router 
doesn't do DHCP or assign addresses at all, it might as well be strictly a 
fast fat switch.

   Internet service is provided by a jumper to a Belkin DHCP router, so 
there are 5 ports tied up on the Linksys(Cisco) switch.   Only one on the 
internet router. The internet service is Cable, with our node fixed, so I 
don't know much other way to do it.

   For whatever reason, the network connection to some of the machines has 
become extremely erratic, inlhouse, on our side..  The network connectivity 
popup in the bottom corner of the screen has started going on and off every 
few seconds... "A network cable is unplugged" -  then about 10 seconds later 
"Local Area Connection 1GbPs  Status Connected" -
On, off, On, Offf...

   It had started on one machine.   I went to a spare network card.  It went 
fine for about a week, now the problems back, but on more than one machine.

   Using Net View and Ping I saw what you'd expect, but... Not.    You can 
see al the machines on the net, but, it pings weird.  Internet and intra-net 
connectivity is on and off and on and off...

   One specific machine address keeps pinging weird.
Put in 'ping 192.168.0.75' - and the screen responds 'pinging 
192.168.0.61'.... notice the difference.
You sometimes get 4 good responses, sometimes get 1, sometimes get none.

   I suspected the router, cached addresses, or something, so I changed all 
out.  Powered down all the machines. Pulled out the Linksys gig router. 
Flushed all the stuff I could by using DHCP from the internet router to each 
machine, ran ran the release all/renew stuff, then reset the correct 
addreses by hand. (the workspace software uses fixed IP's...).  and put the 
Lnksys gig switch back in the net.

   Things run better, at least for now.

I suspect the problem is actually on the machine a x.x.0.75 - as it has a 
program on it installed by corporate... something called NoIP.  Every 
machine  stayed happy for about 5 minutes after I did my fix, but later that 
night (via VNC) I started seeing more dropouts, and found the NoIP stuff 
phoning home a lot.

  I'm tempted to turn the machine with NoIP on it off, and see if the 
network problem goes away...

Jason