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

Chapter 1: Introduction

The RBT-4102C-EU, although listed in this document, is not available until March
Note:
2008.
The RoamAbout RBT-4102, RBT-4102-BG, RBT-4102C, RBT-4102C-EU, and the
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 (not RBT-4102-BG), 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 supports 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 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.
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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