Cisco Cisco 6015 IP DSL Switch

route—The path that network traffic takes from its source to its destination. The route a datagram 
follows can include many gateways and many physical networks. In the Internet, each datagram is 
routed separately.

router—A system responsible for making decisions about which of several paths network (or Internet) 
traffic will follow. To do this, it uses a routing protocol to gain information about the network and 
algorithms to choose the best route based on several criteria known as “routing metrics.” See also bridge.

routing table—Information stored in a router that contains network path and status information. It is 
used to select the most appropriate route to forward information.

Simple Network Management Protocol—See SNMP.

slot—A numbered location within a chassis capable of housing a module.

SNMP—Simple Network Management Protocol. The network management protocol of choice for 
TCP/IP-based internets. 

SNR—signal-to-noise ratio. 

SVC—switched virtual connection. A temporary virtual connection between two users.

T1.413—The ANSI standard for line coding and framing for full rate ADSL.

TCP—Transmission Control Protocol. The major transport protocol in the Internet suite of protocols 
providing reliable, connection-oriented, full-duplex streams.

Telnet—The virtual terminal protocol in the Internet suite of protocols. It allows users of one host to log 
in to a remote host and act as normal terminal users of that host.

TFTP—Trivial File Transfer Protocol. A simple file transfer protocol (a simplified version of FTP) that 
is often used to boot diskless workstations and other network devices such as routers over a network 
(typically a LAN). It does not offer password security.

training—The procedure used by the ATU-C and ATU-R to establish an end-to-end ADSL connection.

training mode—A characteristic of a router that allows it to use RADSL technology to adjust its line 
speed according to noise conditions on the transmission line.

Transmission Control Protocol—See TCP.

trellis encoding—A channel coding technique which provides forward error correction capability.

Trivial File Transfer Protocol—See TFTP.

twisted pair—Two insulated copper wires twisted together with the twists or lays varied in length to 
reduce potential signal interference between the pairs.

utp—unshielded twisted pair. 

upstream rate—The line rate for message or data transfer from the source machine to a destination 
machine on the network. Also see downstream rate.

VC—virtual circuit. A logical circuit created to ensure reliable communication between two network 
devices. A virtual circuit is defined by a VPI/VCI pair, and can be either permanent (PVC) or 
switched (SVC). In ATM, a virtual circuit is called a virtual channel. Sometimes abbreviated VC. 
See also PVC, SVC, VCI, and VPI.

VCI—virtual channel identifier. A

 

16-bit field in the header of an ATM cell. The VCI, together with the 

VPI, is used to identify the next destination of a cell as it passes through to the ATM switch. Sometimes 
called virtual channel connection. See also VPI.

virtual circuit—See VC.

VPI—virtual path identifier. An 8-bit field in the header of an ATM cell. The VPI, together with the VCI, 
is used to identify the next destination of a cell as it passes through the network. See also VCI.