User`s guide

Cayman 3220-H User’s Guide Glossary
December 2000 7
metric Distance, measured in the number of routers a packet must
traverse, that a packet must travel to go from a router to a remote
network. A route with a low metric is considered more efficient,
and therefore preferable, to a route with a high metric. See hop
count.
modem Modulator/demodulator. Device used to convert a digital signal to
an analog signal for transmission over standard telephone lines. A
modem at the other end of the connection converts the analog
signal back to a digital signal.
MRU Maximum Receive Unit. The maximum packet size, in bytes, that a
network interface will accept.
MTU Maximum Transmission Unit. The maximum packet size, in bytes,
that can be sent over a network interface.
NAK Negative acknowledgment. See ACK.
NCP Network Control Protocol.
null modem Cable or connection device used to connect two computing devices
directly rather than over a network.
packet Logical grouping of information that includes a header and data.
Compare frame, datagram.
PAP Password Authentication Protocol. Security protocol within the PPP
protocol suite that prevents unauthorized access to network
services. See RFC 1334 for PAP specifications. Compare CHAP.
parity Method of checking the integrity of each character received over a
communication channel.
PING Packet INternet Groper. Utility program that uses an ICMP echo
message and its reply to verify that one network node can reach
another. Often used to verify that two hosts can communicate over
a network.