I recently ran into the problem of linking two existing ethernet networks in my company.
Our first network has an SHDSL Internet access routed into the network by a SHDSL router. Our network is a heterogeneous, running a mix of Macintosh, Linux and Windows machines. We are in the graphical industry meaning we have heavy loads of files that need to be transfered at quite some speed over the network.
Now we were given a second floor office space by our landlord. However, wiring the network to that second floor seemed to be just unmanageable. A wireless connection would be just the right thing for us - so we thought!
Although the Macs in question are not that old, some Dual Processor PowerPC 1GHz "Mirror Doors," this particular model is just not "Airport Extreme" capable, meaning, you can only plug in an ordinary Airport card (i.e. 802.11b standard, at 11Mbit/s). This, however, would have been definitively too slow for us. I wanted a 802.11g, i.e. 51Mbit/s connection at least! So, what could I do?!
I thought of maybe linking the original network with the new second floor workstations with two Airport Extreme base stations, so I phoned up my dear friend Jason at Apple Store in Ireland - wonder who else is good friends with Jason! He then phoned up Apple Support - and I did the same to maybe even get a second opinion. Both said that owning older Macs, there would be no way of linking them by Airport Extreme, i.e. 802.11g, i.e. 51Mbit/s, i.e. so-called "Wi-Fi" wireless network.
I had a very long look through Internet pages. No answer whatsoever. Phoning up other wireless network vendours also turned out of no help: there was simply no way to join to networks over the air at a speed of 51 Mbit/s. Or was there?!
[robg adds: Read the rest of the article for a detailed solution to this problem. I haven't tested this one, so if anyone can confirm it, please do so via the comments...]
I bought both Airport Extreme base stations and tried myself. After configuring and reconfiguring for about two days, I was successful: my second floor work stations are now linked into the first and home network over the air at 51 Mbit/s - the fastest you can get at present. Here is my setup, which will also work for any kind of operation system provided there is an Airport base station configuration software (currently this is Mac and Windows).
First the setup of the base station within the old/first network: for initial setup, I needed to directly plug the base station into my Mac. I set my network control panel to DHCP to automatically get an IP (this was the default in my network anyway since the SHDSL router routing in the Internet has a DHCP server and all clients obtain their address from this machine.
Next I configured the base station as you would configure any base station (just follow the instructions in the manual or let yourself flow over the settings, basically everything is self explaining anyway). Make sure to give the wireless network a meaningful but not too easy to guess name and for security reasons, switch to closed network to conseal your network name over the air and prevent possible other compatible network cards from next doors to share into your own network.
Now click on the Internet tab. I found out that the naming of the tabs can be a little confusing: the "Internet tab" actually is the configuration of the LAN port of your base station. If you want to operate the base station off an ethernet switch - which you need to do if you are in a larger network anyway, I connected mine directly to a free switch port using a patch cable - you need to give your base station a STATIC tcp/ip-address. Now this is vital! Using DHCP may cause address confusion over the network! I had not thought so, but it proved to be the only way to make the base station configurable through the admin tool if not connected DIRECTLY to your Mac, but rather connected to a switch's port on a network. Make extra sure you use a yet free ip-address within the range of possible addresses set by the DHCP server on your network! If this address is manually assigned, the DHCP server will spare it out from its range automatically and not assign the same address to yet another machine. Enter the DHCP server's IP in the fields "Router" and "DNS-Server". Now save to the Airport and wait for it to reboot. After rebooting it is now safe to de-connect the base station from the Mac and connect it to the network at any given point, i.e. a free router's or switch's port.
Now go back to the admin tool and reconnect logically to your base station. Now go to the Network tab. THIS actually describes the "wireless network side" to the airport. Click on "Share IP-addresses", and click on "use a range". This sets up a wireless DHCP server if you want to be able to connect to the Airport using other Airport clients! Quite useful if you have people with laptops around. For basic office applications, 11 Mbit is fine anyway and PC-Cards compatible to 802.11b are around for about 30 Euros / 30 Dollars anyway. Set a good range, somewhat above the range of your first DHCP server, but make sure it is a valid range under your subnet mask!
Now save everything and connect your second Airport Extreme base station directly to the first remote Mac. Set the same name for the wireless work group and again for security reasons configure as closed network. Make also certain to use the SAME channel as the first Airport to get a connection. The next bit is somehow tricky, since at first the Airports will just not "see" each other! So go to both Airports and jot down their MAC-address for the wireless network side.
At the second Airport, now go to the Internet tab and chose "Airport (WDS)" as network. Below enter the MAC-address of the first Airport (now on the switch or router). Again do manually configure the IP and give it a static address within the range you have set at the wireless DHCP server on the other side!
Click on Network and disable everything. Again, skip the rest and go directly to WDS, configure as remote base station, and enter the MAC-address of the FIRST airport again.
Click on save and let the second Airport boot again. Now you can plug this one to a router on your SECOND network too. Go to your first network and start the admin tool, chose the first Airport, click on WDS, configure as main station, add a new remote and MANUALLY enter the second Airport's wireless MAC address. Save and off you go:
51MBits wireless network bridge !
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030730131925207