T40 Wireless Usage

[jsteele]

My T40 (2369-D5U) is equipped with the IBM 802.11A/B adapter. My home is configured with a DLink DI-764 Router and the printer has a 802.11B Wireless Print Server.

When the T40 is running in 802.11A mode I am unable to access the print server. I can get to the Internet and access other PCs on the WLAN -- some of which use Netgear HA501 802.11A, Orinoco Silver and 3Com 802.11B PCMCIA cards. However, all of the other PCs can access the print server and my T40 can do so in 802.11B mode, just not when running 802.11A.

I have tried everything I can think of including different print servers (a DLink 311 and a TrendNet P1P) and a different router (Linksys WRT55AG) always with the same results. Only my T40 cannot find the print server and only when running in 802.11A.

I'm curious if anyone has seen anything like this and has some suggestions.

[JHEM]

Why would you expect to connect to a 11b only device when you're running your laptop's WiFi NIC in 11a mode?

You've lost me.

Regards,

James

[jsteele]

Because they are both part of an infrastructure WLAN.

Logically all the devices on the WLAN are part of the same LAN regardless of how they are connected 802.11A, 802.11B or Ethernet. Other 11A devices can access it, and I can access other 11B devices, just not the silly print server for some reason.

If this were ad-hoc network I'd say you are right --- in that case the 802.11A and 802.11B networks would be entirely separate --- but the router is essentially "bridging" 11A, 11B and 100baseT together.

[JHEM]

But you didn't say you were using your router to bridge the network, you said that you can't connect directly to a 11b print server when your laptop is running in 11a.

Your laptop needs to be running in 11b mode to connect to your print server. Or upgrade the card in your server to 11a/b.

Logic's go nothing to do with it.

Regards,

James

[jsteele]

I think we have a failure to communicate here.

When I said I was using a 802.11A/B router I didn't think I needed to say that the 'backside' interfaces are logically bridged --- that sort of goes with the territory in an infrastructure network. The T40 is connected to the router on 11A. The print server is connected to the router on 11B. Both devices are part of the same TCPIP subnet and thus logically are part of the same LAN. If the subnet is different the router sends the data to the WAN Ethernet interface to go to the DSL; if the subnet is the same it sends it to the 11A, 11B and wired interfaces for distribution on the LAN ALL the devices on the "back side" of the router are on the same logical LAN regardless of whether they are connected via 11A, 11B or wired Ethernet.

So there is no logical reason why an 11A connected device cannot exchange data with an 11B device or an Ethernet connected device. And I know this to be true --- I can connect in 11A mode to devices the wired Ethernet ports of the router, and other 11A devices on the network (such as my #1 daughter's desktop and my #2 daughter's 600X) connect in 11A mode to the 11B print server and other 11A and/or wired Ethernet without a problem.

The problem is restricted to my T40 in 11A mode and 11B devices.

[jsteele]

I experimented most of the evening and found something interesting (at least I thought it was interesting

It turns out that the print server was configured to use 11B channel 10 and the dual mode router and all the other 11B devices, as well as my T40 in 11B mode, were using channel 6. All the 11B devices in the house were able to talk to the print server even though they were set for different channels. And the 'other' 11A devices were able to use the print server just fine.

When in 11B mode my T40 would communicate with the print server, again regardless of the channel settings. But in 11A mode it would not. When I changed the print server to channel 6 like all the other 11B devices, they continued to work with the print server as did the other 11A devices.

But voila, now my T40 was able to talk to it in either 11B or 11A!

I find that to be truly bizarre. I fail to see why the mismatched 11B channel settings did not make a difference to ANY 11B device and other 11A devices, but did to my T40 but only in 11A mode.

Anyway problem solved so if anyone else encounters strange wireless behavior don't overlook the truly obscure possibilities. Wireless networking is still a bit of a 'black art.'