Nortel Networks NB5PLUS4/W - Manual (Page 105)

YML754 Rev1 NB5Plus4/W User Guide
www.netcomm.com.au 105
splitterless A type of DSL installation where no splitter is installed,
saving the cost of a service call by the telephone compa-
ny. Instead, each jack in the home carries both voice and
data, requiring a microfilter for each telephone to prevent
interference from the data signal. ADSL is usually split-
terless; if you are unsure if your installation has a splitter,
ask your DSL provider. See also splitter, microfilter.
subn­et A subnet is a portion of a network. The subnet is dis-
tinguished from the larger network by a subnet mask
which selects some of the computers of the network
and excludes all others. The subnet’s computers remain
physically connected to the rest of the parent network,
but they are treated as though they were on a separate
network. See also network mask.
subn­et mask A mask that defines a subnet. See also network mask.
TCP See TCP/IP.
TCP/IP Transmission Control Protocol/Internet Protocol The basic
protocols used on the Internet. TCP is responsible for di-
viding data up into packets for delivery and reassembling
them at the destination, while IP is responsible for deliv-
ering the packets from source to destination. When TCP
and IP are bundled with higher-level applications such as
HTTP, FTP, Telnet, etc., TCP/IP refers to this whole suite of
protocols.
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 tel-
ephone 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