A long-haul network technology that is able to send data synchronously at 1554Mbps. T1 circuits are often broken up in distinct channels to create a fractional T1.
Transmission Control Protocol. TCP is a connection-oriented Layer 4 protocol built on top of the IP Network Layer. It provides reliable delivery of packets across an IP network.
Transmission Control Protocol/Internet Protocol. TCP/IP refers to the suite of IP protocols to make a distinction from IP, which can just refer to the Layer 3 part of the protocol.
Telnet is a terminal-access program that runs over a TCP connection. It allows character-based interactive access to remote IP devices.
A device that has a number of low-speed serial ports and a LAN port. Terminal servers are used primarily to connect a number of character-based user terminals to a network.
Trivial File Transfer Protocol. TFTP is a simple file transfer protocol that is frequently used to download configuration information into devices at boot time.
See 10Base5.
See 10Base2.
In token-passing networks, a small frame. This frame is passed around the network from device to device. Only the device that is currently in possession of the token can transmit data onto the network.
A standard LAN protocol that is defined in the IEEE document 802.5. It consists of a simple-ring topology where devices pass a small token frame from neighbor to neighbor to indicate permission to transmit data.
Type of Service. The TOS field is a standard component of the IP packet header. It is renamed as Distributed Services Control Point (DSCP) and used slightly differently in some implementations.
A program that sends out a series of probes to attempt to determine the actual path that the network provides to a particular destination. It is a useful troubleshooting tool.
Refers to the technique of flattening out bursts of traffic by means of buffering some packets and dropping others.
Transmitter/Receiver. Referred to as a Media Attachment Unit (MAU) in some literature, this book uses the term Transceiver to avoid confusion with the Token Ring device mentioned in this glosslist. A transceiver is generally a device that connects one network's physical medium to another. The most common implementations connect the generic physical sublayers such as AUI, MII, and GMII to specific physical implementations such as 10BaseT, 100BaseT, and 1000BaseT. But there are also transceivers that connect, for example, 100BaseT to 100BaseFx.
See TCP.
In SNMP, an unsolicited packet sent from a device to its server, usually to indicate an error condition.
A network link that is used to aggregate the traffic from several downstream sources into a single stream.
Time To Live. In IP networks the TTL field is a number between 0 and 255 that indicates how many more hops the packet can be forwarded through before it is dropped. The TTL field is used to limit scope in some multicast applications, and more generally, it helps break routing loops.
A general term that means that one protocol is carried inside of another temporarily. Tunnels are used to create connections between separate parts of a network. This is sometimes done because the tunneled protocol is not able to propagate through the intervening network for technical reasons. Tunnels are also frequently used for security reasons.
See TOS.