WPIM-SY LOCAL MANAGEMENT GUIDE
B-1
APPENDIX B
WAN TERMS AND ACRONYMS
This appendix provides definitions for WAN terms and acronyms.
AMI
Alternate Mark Inversion, line coding used with both E-1 and
T-1. A digital 1 is encoded as a “mark” (pulse) and a 0 is
encoded as a “space.” The marks alternate polarity.
ANSI
American National Standards Institute, the US member of the
ISO.
Bearer (B)
Channel
A 64 Kbps channel used with BRI and PRI ISDN services.
Bipolar
Violation
The occurrence of two successive pulses of the same polarity
in a bipolar signal.
B8ZS
Binary 8-Zero Substitution, line coding utilized with ESF
(Expanded Super Frame). Insures the ones density requirement
for digital T-carrier facilities in the public network, while
allowing 64 Kbps clear data per channel.This encoding method
is not supported by some Telcos.
BRI
Basic Rate Interface, minimum rate ISDN subscriber interface,
provides 2 B + 1 D channels (two 64 Kbps “B” (Bearer) chan-
nels and one 16 Kbps “D” (Data) signaling channel for a total
of 144 Kbps).
BRIM
Cabletron Systems Bridge Router Interface Module. Expands
the physical connectivity of a host device.
CRC
Cyclic Redundancy Check, an algorithm or process used to
identify corrupted packets in the transmission link.
CSU
Channel Service Unit, a device that terminates the local
loop/digital channel on a customer’s (DSU) premises. The
CSU connects to a DSX-1 interface on the CPE.
