Thursday, February 09, 2006

Issue: Linksys Wireless-B router quits after reaching max DHCP IP address?

A few months ago, I replaced my old non-wireless Linksys router with a new Linksys Wireless-B router. At the time, I wanted the router so that I could get online with my PocketPC around the house. I also subsequently got a TiVo as a Christmas gift (thanks Dad!) which uses the online network to talk to the TiVo server out on the Internet to download new schedule information.

Earlier this week, my PocketPC stopped working on the wireless network. It could see the router with no problem with "Excellent" signal strength, but it was apparently unable to get an IP address; it reported a 169.x.x.x address instead of a real 192.168.x.x address.

Unfortunately, the PocketPC provides very poor error reporting when it has a problem getting on the network -- no error message any more detailed than "unable to connect" appears.

I tried assigning the PocketPC network card a static IP address instead of having it dynamically pick up an IP from the router. With the static IP, I was able to get online successfully, which seemed to indicate that the issue was with the DHCP server. I didn't want to leave the static IP in place, though, since it would mean that my PocketPC would be unlikely to connect successfully on wireless networks other than my own.

After looking at many other settings in the router's browser-based configuration application, I took a look at the Wireless Client MAC List under Wireless | Wireless Network Access. My PocketPC did not appear on the table, but the TiVo appeared, with an IP of This tickled my memory; I remembered seeing on the main page of the config app that the router's DHCP was set to assign up to 50 dynamic IPs, in the range 103 through 152 (with 100 through 102 being reserved as static IPs for my desktop machines).

I returned to the main page in the config app, and extended the count of available DHCP IPs from 50 to 100, in the range 103 through 202. Immediately after saving this new setting, my PocketPC was able to successfully get a valid IP! It got (skipping 153 for whatever reason).

So as far as I can tell, the problem is that the router assigned dynamic IP addresses (as the leases on existing addresses expired) in sequence starting with 103 and eventually reaching 152. Instead of wrapping back around to 103 as I would expect, it apparently just decided to quit assigning new dynamic IPs at that point!

Is this a bug in the router software? The status page reports that the firmware version is "1.50.14, May 27 2004". I may need to look into whether an update is available so I don't run into this issue again once the router issues another 50 IPs and reaches the new cap of!

In the meantime, though, between troubleshooting this issue and typing up this post, it's past my bedtime, so any further investigation will have to wait until another time!

1 comment:

  1. Very clear description of the problem and your steps in solving it! Thanks Jon. I think you're awesome. Love, Mom


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