Nortel Passport 4400 Using Manual page 138

138
X.121
ITU-T specification describing an addressing scheme used in public data
networks, for packet-switching between data devices.
X.21
Standard interface approved by the Electronic Industries Association (EIA)
for connecting high-speed (above 19.2 kb/s) data communications equipment.
X.25
The ITU-T and ISO-recommended multipoint connection-oriented service
that uses either permanent virtual circuits (PVC) or switched virtual circuits
(SVC) over a physical link. It uses HDLC framing to separate frames
zero suppression
One of three schemes used to insure ones density. See also B8ZS, HDB3, and
Bit Stuffing.
206906-D Rev 00 4.2