U.S. Robotics SureConnect ADSL Ethernet/USB Router User Guide

intervals. The user can specify how much bandwidth that he wishes to reserve.

CDVT (Cells) - Parameter that constrains the number of cells that the user can send to the network at the maximum line rate.

Cycle - One half of a periodic wave. For instance, a sinewave includes one positive and one negative cycle.

D

DHCP (Dynamic Host Configuration Protocol) - Protocol for automatic TCP/IP configurations. DHCP provides static and dynamic address allocation and management.

DHCP Relay - Suppose that a Dynamic Host Configuration Protocol (DHCP) server resides on a different LAN than the node broadcasting for DHCP service. Then the DHCP broadcast request must be forwarded across the router/WAN to a subnet where a DHCP server resides. To assure receipt of an IP address that corresponds to this subnet, the router must use a DHCP relay. The router needs to know the IP address of the DHCP server. With this address, the router can direct the request to the appropriate DHCP server.

DMT (Discrete Multitone) - Most common DSL modulation method. DMT creates 256 channels across the usable frequency spectrum. Each channel measures 4.3125KHz wide. Dividing the spectrum into channels allows DMT to function well in spite of nearby AM radio transmitters. The DMT modulator and demodulator is the FFT (Fast Fourier Transform) algorithm. Inside each channel, the modulation technique is QAM. Within each channel, the number of bits per symbol may be independently selected. Independent selection allows a DMT modem to be rate adaptive. Both G.DMT and G.Lite use DMT.

DNS (Domain Naming System) - Mechanism used in the Internet for translating names of host computers into IP addresses.

DNS Relay - DNS requests that the router forwards from a LAN node to a known DNS server. The router uses a DNS relay when the router functions as a NAPT (Network Address Port Translation) device. The requests arrive at a DNS server over the WAN link. To function as a NAPT, the router requires DNS relay settings.

DSLAM (Digital Subscriber Line Access Multiplexer) - Network device that receives signals from multiple customer Digital Subscriber Line connections. DSLAM places signals on high speed lines with multiplexing techniques for the fastest phone line technology available.

E

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