P
Glossary
B-58
Centillion 1200N ATM Switch User Manual
NTP 297-8103-903
PLL
Phase Lock Loop: Phase Lock Loop is a mechanism whereby timing information
is transferred within a data stream and the receiver derives the signal element timing
by locking its local clock source to the received timing information.
PLO
Phase Locked Oscillator
PM
Physical Medium: Physical Medium refers to the actual physical interfaces. Several
interfaces are defined including STS-1, STS-3c, STS-12c, STM-1, STM-4, DS1,
E1, DS2, E3, DS3, E4, FDDI-based, Fiber Channel-based, and STP. These range
in speeds from 1.544Mbps through 622.08 Mbps.
PMD
Physical Media Dependent: This sublayer defines the parameters at the lowest
level, such as speed of the bits on the media.
PNI
Permit Next Increase: An ABR service parameter, PNI is a flag controlling the
increase of ACR upon reception of the next backward RM-cell. PNI=0 inhibits
increase. The range is 0 or 1.
PNNI
Private Network-Network Interface: A routing information protocol that enables
extremely scalable, full function, dynamic multi-vendor ATM switches to be
integrated in the same network.
PNNI Protocol Entity
The body of software in a switching system that executes the PNNI protocol and
provides the routing service.
PNNI Routing Control Channel
VCCs used for the exchange of PNNI routing protocol messages.
PNNI Routing Domain
A group of topologically contiguous systems which are running one instance of
PNNI routing.
