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IEEE 802.10 Local and Metropolitan Area Networks Interoperable Security IEEE 802.10 and the substandard 802.10b Secure Data Exchange (SDE), describes a frame-tag type of security system. Each frame in a transmission are tagged with a security code for identification and authorization. It provides an ISO layer 2 security protocol offering confidentiality and connectionless integrity, which can be used to protect transmissions over LANs and MANs. Substandard 802.10e extends the security service of 802.10 to Ethernet V2.0 Media Access Control Protocol Data Unita. Substandard 802.10f specifies a set of managed object classes for the management of the SDE sublayer and its protocol exchanges. Another network standards body is advocating a frame-tagging system for security that is different from 802.10. Members of this body include Cabletron Systems, Inc., 3Com Corporation, and Cisco Systems Inc. It should be noted that Cisco was one of the original sponsors of the 802.10 standard. They now admit that 802.10 does not work well with virtual LANs (VLANs). IEEE 802.11 Wireless Local Area Networks Wireless LANs, in which a station communicates with a central unit by means of radio waves, infrared light, or visible light are becoming popular because they are, in some applications, more flexible and less expensive than hard wired networks. To improve flexibility and lower prices, the industry is looking for a universal standard. At least, units from different vendors should not interfere with each other. Ideally, every unit of whatever vendor and model should be able to interoperate. This venture has been assigned to the IEEE 802.11 Working Group on Wireless Medium Access Control and Physical Layer. The use of radio waves requires the authorization of international and national regulatory agencies. In the United States the Federal Communications Commission (FCC) has allocated the following frequency bands for spread spectrum devices:
Further, the bank 8.890 GHz to 1.930 GHz is available for unlicensed personal communication services (PCS), and the band 18.8 GHz to 19.2 GHz for data communications. Other regions of the world offer other frequency bands. The 2.4-GHz is the most promising for worldwide availability but it is used by microwave ovens. The 1.9-GHz band is subject to different rulings in the US and Europe. In the US it is assigned for spread spectrum utilization, while in Europe it is dedicated to digital European cordless telecommunications (DECT). The European Telecommunications Standards Institute (ETSI) is considering a standard for High Performance Local Area Networks (HIPERLANs) for operation in the 5.2-GHz band. In Japan the Research and Development Centre for Radio Systems (RCR) is considering use of the 2.4-GHz to 2.5-GHz band for spread spectrum applications and the 18-GHz to 19-GHz bands for radio LANs (RLANs). For RLANs the 802.11 committee is concentrating on obtaining global approval for the use of the 2.4-GHz band. All IEEE 802 committees are aiming at a data transmission bit rate of 20M to 100M bps. All 802.11 networks will provide for data encryption according to the IEEE 802.10 Interoperable LAN/MAN Security standards. The IEEE 802.11 committee is considering frequency-hopping spread-spectrum radio, direct-sequence spread-spectrum radio, and pulse-position modulation infrared light for the physical layer. For practical and economic reasons the committee concentrated on the spread-spectrum technologies. Even though the frequency bands allocated by the FCC allows for transmission rates of up to 10M bps, the standard specifies alternatively 1M bps or 2M bps. Generally, the practical throughput is much lower, often as low as 0.5M bps.(Lower practical rates are also the case with Ethernet, etc.) A higher air speed can result in a lower throughput due to an increased rate of retransmissions. The range of 802.11 systems depends to a large degree on the environment and is not specified in the standard. A range of 60 to 90 meters (200 to 300 feet) can be expected in an office environment. The FCC mandates a maximum power of 1 W or 30 dBm (decibels relative to 1 mW). The media access layer uses an algorithm similar to the CSMA/CD used in IEEE 802.3. However, collisions cannot be detected in the radio environment, only avoided. The spread-spectrum and the infrared light versions use the same MAC. The frames contain headers, payload, and error-protection trailers. The frames are the same independent of the type of attached wired LAN (802.3 Ethernet or 802.5 Token Ring). The frames are converted from one form to another at the access points. Wireless can be applied to both trunks and access links, i.e. between two LANs, as well as between terminals and LANs. The efforts of the IEEE 802.11 committee are concentrated on the use of wireless for access to LANs.
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