Chapter 1: Introduction - Enterasys RoamAbout RBT-4102 Installation Manual

Chapter 1: Introduction

The RoamAbout RBT-4102 and RBT-4102-EU are IEEE 802.11a/b/g access points
that provide transparent, wireless high-speed data communications between the
wired LAN 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, that is 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 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 conectivity 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.
Radio Characteristics – 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).
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