SMC Networks ADSL Barricade SMC7204BRA - Manual (Page 193)

Terminology
197
Telnet
An interactive, character-based program used to access a remote
computer. While HTTP (the web protocol) and FTP only allow
you to download files from a remote computer, Telnet allows
you to log into and use a computer from a remote location.
TFTP (Trivial File Transfer Protocol)
A protocol for file transfers, TFTP is easier to use than
File Transfer Protocol (FTP) but not as capable or secure.
TTL (Time To Live)
A field in an IP packet that limits the life span of that packet.
Originally meant as a time duration, the TTL is usually
represented instead as a maximum hop count; each router
that receives a packet decrements this field by one. When
the TTL reaches zero, the packet is discarded.
twisted pair
The ordinary copper telephone wiring long used by telephone
companies. It contains one or more wire pairs twisted together to
reduce inductance and noise. Each telephone line uses one pair.
In homes, it is most often installed with two pairs. For Ethernet
LANs, a higher grade called Category 3 (CAT 3) is used for
10BASE-T networks, and an even higher grade called Category
5 (CAT 5) is used for 100BASE-T networks. See also 10BASE-T,
100BASE-T, Ethernet.
upstream
The direction of data transmission from the user to the Internet.
VC (Virtual Circuit)
A connection from your ADSL routers to your ISP.