Chapter 1: Introduction; Overview - Enterasys RoamAbout RBT-4102 Configuration Manual

Overview

The RoamAbout RBT‐4102, RBT‐4102‐BG, and RBT‐4102‐EU, are IEEE 802.11a/b/g access points
that provide transparent, wireless high‐speed data communications between the wired LAN
(WLAN) and fixed or mobile devices equipped with an 802.11a, 802.11b, or 802.11g wireless
adapter. This solution offers fast, reliable wireless connectivity with considerable cost savings over
wired LANs (which include long‐term maintenance overhead for cabling). Using 802.11a and
802.11g technology, these access points can easily replace a 10 Mbps Ethernet connection or
seamlessly integrate into a 10/100 Mbps Ethernet LAN.
The RBT‐4102 and RBT‐4102‐EU support up to eight Virtual Access Points per physical radio
interface, eight on the 802.11a radio and eight on the 802.11g radio. This allows traffic to be
separated for different user groups using an access point that services one area. For each virtual
access point (VAP), different security settings, VLAN assignments, and other parameters can be
applied. Each radio interface on the RBT‐4102 and RBT‐4102‐EU can operate in one of three
modes:
• Access Point – Providing connectivity to wireless clients in the service area.
• Bridge (Point‐to‐Point) – Providing links to other access points in "Bridge" or "Root Bridge"
mode connecting wired LAN segments.
• Root Bridge (Point‐to‐Multipoint) – Providing links to other access points in "Bridge" mode
connecting wired LAN segments. Only one unit in the wireless bridge network can be set to
"Root Bridge" mode.
In addition, the access point offers full network management capabilities through an easy to
configure web interface, a command line interface for initial configuration and troubleshooting,
and support for Simple Network Management tools.
The IEEE 802.11a/g standard uses a radio modulation technique known as Orthogonal Frequency
Division Multiplexing (OFDM), and a shared collision domain (CSMA/CA). It operates at the
5 GHz Unlicensed National Information Infrastructure (UNII) band for connections to 802.11a
clients, and at 2.4 GHz for connections to 802.11g clients. IEEE 802.11g includes backward
compatibility with the IEEE 802.11b standard. IEEE 802.11b also operates at 2.4 GHz, but uses
Direct Sequence Spread Spectrum (DSSS) and Complementary Code Keying (CCK) modulation
technology to achieve a communication rate of up to 11 Mbps. The access point supports a
54 Mbps half‐duplex connection to Ethernet networks for each active channel (up to 108 Mbps in
turbo mode on the 802.11a interface).
RoamAbout RBT-4102 Wireless Access Point Configuration Guide 1-1
1
Introduction