PC NIC not giving/getting MAC address, no Internet

[WildHare]

Hope this is the appropriate forum...

About 6 weeks ago, one of my clients went to cable internet service in their office. I installed an 8-port Netgear router/VPN Firewall guy which they all plugged into, with a Linksys hub on the uplink port because, of course, they added a NINTH pc to the mess. The Netgear is RJ45'd to the Comcast-supplied cable modem.

When I first set it up, everything worked fine - each machine got an IP address, they all connected right off the bat,it was a piece of cake, literally. Didn't change one thing out of the box re: Router settings.

Then about a week ago, one of the users shut his machine down (they normally stay powered on) due to fears of SoBig and such - when he came in the next day, his machine could not get an Internet connection. He logged into the workgroup just fine, but the router just didn't see him.

This isn't my normal area of expertise, but I tried the usual routes of checking cables (but if he was on the workgroup, his NIC and cable would seem to be working just fine). I removed and reinstalled TCP/IP, removed and redid his Network Connection, and even gave him a new NIC. NO change.

I noticed that the router's configuration screen did NOT see him as an attached device - and an IPCONFIG on his machine showed some differences from all the others. For example, it did not see the router's default gateway IP or anything like that. It was like the PC simply did not see the router there.

Then yesterday a few more users reported that they could not get a 'net connection. I went over after work, and they all showed similar behavior.

To cut a long story short, I ended up resetting the TCP/IP configuration on ALL The machines, to use a preset IP address (from the router's range) and use the router's IP for gateway and DNS.

I have a feeling this may be a tenuous fix, at best. Does anyone have a clue why a machine might suddenly refuse to play nice with all the other guys?

If I remember my basic networking, the MAC address is sent from the CARD to the ROUTER, right? Or is that backwards?

I'd appreciate any thoughts.. thanks much.

Jim

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[DG659]

YOur DHCP is misconfigured you got a lease first of now theve reached expiry your losing connection

bet the DSL has a DHCP and also you Router turn the DSL dhcp OFF and your Router On

how id start
1) note the IP of the DSL (my guess 192.168.100.254 subnet 255.255.255.0) and the router (again a guess 192.168.1.2 subnet 255.255.255.0)
2) Turn everything OFF except 1 PC and the DSL and the switch/hub
3) connect the DSL and the PC direct to the hub
4) set a pc ip to the same range (ie. 192.168.100.100 subnet 255.255.255.0)
5) open the DSL config page and disable DHCP then save and reset DSL.
6) connect the DSL to the WAN port on the Router and the router to the HUB/Switch.
7) set The pc ip to the same range (ie. 192.168.1.100 subnet 255.255.255.0)
8) go to Routers config set the wan to accept a static IP using the IP of the DSL (i.e 192.168.100.2 subnet 255.255.255.0 with a gateway address of 192.168.100.254 subnet 255.255.255.0 and DNS suplied by your ISP if you dont know them try these till you find the correct ones 194.72.6.57 and 62.31.64.115)
9) next set the LAN section up to use a IP of 192.168.1.1 subnet 255.255.255.0)and enable DHCP .
10) save and reboot the router
11)set the PC back to dhcp also and reboot.

I ve just seen a prob in that the router and Hub/switch are the same device if you can connect the PC direct to the DSL rather than the HUB/Switch when configuring the DSL

 

[GlenJohnson]

I've had similar problems with my home wireless router. My fix came by powering down the cable modem, and the router, powering up the router first, then the modem. I got this from the cable company. When it hasn't worked, the cable company is having problems. good luck.

Glen A. Johnson
Johnson Computer Consulting

http://www.johnsoncomputers.us

"The best fire does not flare up the soonest."
George Eliot (1819-1880); Englist novelist.

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[WildHare]

Thanks both for the tips - I did some searching, and it is apparent that APIPA is being invoked on the NICs for some reason (Automatic Private IP Addressing) It's addressing the cards using the 169.254.xxx.xxx series, I think, which is what MS has 'reserved' for internal use in 2K and XP (and possibly earlier). Over the weekend, I'm going back and checking out the suggestions outlined above, and also tweaking each PCs registry to turn off APIPA. I'll let you know how it turns out.

Jim

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[ricpinto]

Just follow dg659 suggestion. You're getting the APIPA address because no DHCP responded to your PC's.

 

[warrenliang]

Hello:

I have DHCP server on an AIX host. Like to find out which laptop owns a particular address. How can I display the current leased-out addresses and their owners MAC?

Thanks.
Warren

 

[DG659]

i know nothing about AIX sorry. In Windows youd just look at the DHCP manager on server under lease you see the MAC IP and M/c Name

 

[BigShyBear]

Going back to Wildhare's original request, the DHCP service on the Netgear router had hung and halted. This happens. Fix is to reboot the router, i.e. turn it off and turn it on. Quite often you have to cycle the cable modem too to resync with
Long term, you'll need to either teach the customer how to turn the router off and back on again, or make a practice of going into their office about every 2 months and doing it yourself.
I always put these things on 2 separate cheap ($3) power strip with the on/off switchs on the power strips labeled as to which one is which, and put them in such a position that we can get to them. I make sure the customer knows to power off both, then power the cable modem on first, wait for it to sync, then power the router back up.