The Wireless Distribution (WDS) Tab

This tab contains some of the identity information for your ABS.

With the "Extreme" ABS, Apple unfurled a system it calls Wireless Distribution System (WDS), commonly known as bridging and relaying. WDS allows base stations to relay information not only to adjacent computers but to other base stations as well. Thus, you could set up one main base station that feeds many other base stations wirelessly. Below is a hypothetical 4 base station network.

Once set up, your ABS' will talk to each other and route traffic from station to station. This feature is especially relevant for those of us who live in old homes or rent and don't want to poke holes in the walls unless we absolutely have to. However, there is no free lunch.

Keep in mind that the maximum speed you'll encounter is always limited by the worst bottleneck in the system. For instance, the speed of the connections between base stations is inversely proportional to the distance between them. Thus, even "Extreme" ABS' will only talk at 1MBit/s with each other if they're far apart (i.e. 54x lower than their maximum theoretical speed). Under such circumstances, multiple remote base stations could saturate the link between the main base station and the relay, causing massive slow-downs.

Unfortunately, I am not sure that a true "Daisy-Chain" topology is possible - I don't own a gaggle of "Extreme" base stations to test this out. The Apple design guide only mentions Relay-to-Main ABS connections, not Relay-to-Relay. If anyone knows what is possible, please enlighten me! On the other hand, few of us will need a "Daisy-Chain" longer than what Apple is supporting explicitly. Such a chain is likely to be far less expensive than retrofitting proper CAT5 ethernet wiring and base stations throughout a structure. Judging from my reader-email, this feature may be just the most compelling reason to upgrade to a new "Extreme" Base Station.

As the sketch above implies, there are basically three operating modes for a base station in a WDS network: Main Base Station, Relaying Base Station, and Remote Base Station. Your first step will be to enable WDS. I will refer several times to something called a Airport MAC address. This is the hardware ID associated with your wireless transceiver.

To find the Airport MAC address look underneath the base station. On the bottom of every "Extreme" ABS you will find three MAC addresses. The one of interest in WDS applications is the one with the Airport symbol next to it (three semi-circles that look like a old representation of a radio transmission). The other two MAC are for the WAN port (circle of stones) and the LAN port (<···>). Next, I will treat each WDS operating mode your ABS can function as individually below.

Main Base Station

This is the base station that supplies the rest of your wireless network with a connection to the internet.

First, you have to decide whether this ABS can be used by wireless computers as well as base stations. If the Main ABS is to be used in a Point-to-Point configuration (i.e. long distance link), un-check this box for greater security. Otherwise, leave it enabled

Next, you have to enter the information for all base stations that you want to allow to connect to this ABS. If the base stations are all in range, they should all pop up once you press the "+" key. Otherwise, you'll need the Airport MAC address that is found on the underside of your relaying or remote base stations. If you're building a or several "Daisy-Chain"(s) of base stations relaying to each other, only enter the Airport MAC address of the first link in each chain. That maximizes throughput.

Relay Base Station

As the sketch above implies, a "Relay" base station acts as a relay between multiple base stations. Apple seems to support only Main ABS-Relay connections. It would be interesting if anyone could test whether Relay Base stations can relay from one to the next, like a true Daisy-Chain to cover vast areas. Since the Relay base station derives its signal from another base station, the maximum speed attainable through a relay base station is the slowest "upstream" connection.

First, you have to decide whether this ABS can be used by wireless computers as well as base stations. If the Relay ABS is to be used in a Point-to-Point configuration (i.e. long distance link), un-check this box for greater security. Otherwise, leave it enabled

Next, you have to enter the Airport MAC address of the Main Base Station. You may even be lucky enough to be able to "Select" it.

Lastly, you have to enter the information for all base stations that you want to allow to connect to this ABS. If the base stations are all in range, they should all pop up once you press the "+" key. Otherwise, you'll need the Airport MAC address that is found on the underside of your relaying or remote base stations. If you're building a or several "Daisy-Chain"(s) of base stations relaying to each other, only enter the MAC address of the first link in each chain. That maximizes throughput.

Remote Base Station

As the sketch above implies, a "Remote" base station is the last link in the chain. It may be connected wirelessly to the Main ABS or a Relay ABS. Since the Remote base station derives its signal from another base station, the maximum speed attainable through a relay base station is the slowest "upstream" connection.

First, you have to decide whether this ABS can be used by wireless computers as well as base stations. If the Relay ABS is to be used in a Point-to-Point configuration (i.e. long distance link), un-check this box for greater security. Otherwise, leave it enabled

Next, you have to enter the Airport MAC address of the Main Base Station. You may even be lucky enough to be able to "Select" it.

For a step-by-step thriller on how to set up WDS, I wouldn't look further than Paula de la Cruz' tutorial in the Apple Discussion boards.

Done. Hit upload and Happy Surfing. If anyone can e-mail me regarding long daisy-chains with Relay base stations, that would be great. Cheers!