About the CSX40016 CSX400 and CSX400-DC User’s GuideHDSLHigh-bit rate Digital Subscriber Line (HDSL) technology uses existing copper twisted pair cablesdesigned for conventional analog voice transmission from a telephone carrier servicing area as alow-cost alternative to the quality and speed of fiber optic cables, and provides high-speedfull-duplex digital transmission links of up to 1.544 Mbps. The WPIM-HDSL is easy to install inyour network over existing telephone lines, and it is a portable investment if a business, orindividual user plans to relocate.HDSL is a direct connection technology that allows connections to be made for distances of up to12,000 feet over 24 American Wire Gauge (AWG) unconditioned Twisted Pair wire. To obtain theFull T1 line Rate of 1.544 Mbps, two wire pairs are necessary (four wires). If one pair of wires isused (two wires), then data rates of 772 Kbps are supported, which is equivalent to one-half of aT1 line.Bridging and RoutingBridging — Bridging connects two or more separate networks together. The bridge examines aportion of each network frame called the header. This header contains control information for theframe. The bridge compares the destination address of the frame to a table of source addresses(bridges dynamically learn the physical location of devices by logging the source addresses ofeach frame and the bridge port the frame was received on in the source address table). Intransparent bridging, the decision to forward the frame is based on this comparison. If the addressindicates that the sending station and the destination station are on the same side of the bridge, theframe is not forwarded across the bridge. If the addresses do not indicate that, the bridge forwardsthe broadcast frame across the bridge to the other network(s).Bridging allows frames to be sent to all destinations regardless of the network protocols used. Italso allows protocols that cannot be routed (such as NETBIOS) to be forwarded, and optimizesinternetwork capacity by localizing traffic on LAN segments. A bridge extends the physical reachof networks beyond the limits of each LAN segment. Filters can be used to increase networksecurity in bridged networks, and restrict message forwarding by using user-built addresstables (non-transparent bridging).
