Add a Repeater or Bridge

Add a Repeater or Bridge
Wireless repeaters are an alternative way to extend the range of an existing
wireless network instead of adding more access points. We talk earlier in the
book about the role of bridges and repeaters in a wireless network. The topic
of bridges can be pretty complex, and we don’t want to rehash here — go
back and read Chapter 2 for all that juicy detail.
Not many standalone repeaters are on the consumer market. However, what’s
important for our discussion is that repeater capability is finding its way into
the AP firmware from many AP vendors. A wireless AP repeater basically does
double duty — it’s an AP as well as a wireless connection back to the main AP
that’s connected to the Internet connection.
At its most basic level, a repeater simply regenerates a wireless network
signal in order to extend the range of the existing wireless LAN. You set the
two devices to the same channel with the same Service Set Identifier (SSID),
thus effectively broadening the collective footprint of the signal.
If you’re having throughput performance issues because of interference or
reach, putting an access point into repeating mode might help you extend the
reach of your network. One review of the D-Link (www.d-link.com) DWL-
900AP+ saw a 50 percent improvement in reach.
However, it’s not clear that adding a repeater helps actual throughput in all
situations, unfortunately. Some testing labs have cited issues with throughput
at the main AP because of interference from the new repeating AP (which
is broadcasting on the same channel). Others note that the repeater must
receive and retransmit each frame (or burst of data) on the same RF channel,
which effectively doubles the number of frames that are sent. This effectively
cuts throughput in half. Some vendors have dealt with this issue through
software and claim that it’s not an issue.
It’s hard to make a blanket statement at this juncture about the basic effectiveness
of doing an AP in repeater mode, particularly versus the option of
running a high-quality Ethernet cable to a second AP set on a different channel.
If you can do the latter, that’s preferable.
When using the bridging/repeating functions of AP/bridges, we recommend
that you use the same product at both ends of the bridge to minimize any
issues between vendors. Most companies support this functionality between
their products only.