E-14 Cisco BPX 8600 Series Reference
partially-interleaved EIA
One control lead in each direction, generally RTS-CTS, is transmitted in same byte as seven data
bits. For fast control lead response to data being turned on and off.
PBX (private branch exchange)
Digital or analog telephone switchboard, classified as customer premise equipment (CPE), used
to connect private and public telephone networks.
PCM (Pulse Code Modulation)
The system for transmitting telephone signals digitally. Voice is sampled 8000 times per second
and converted to an 8-bit digital word.
PCR (Peak Cell Rate)
The maximum rate for an ATM connection at which cells are allowed into the network.
PCS (Port Concentrator Shelf)
The PCS is an external shelf that expands the capacity of the FRP card. The PCS is sued with the
FRP-2 (IPX switch) or FRM-2 (IGX switch) card to 44 frame relay connections. The PCS
connects to the FRI-2.X.21 backcard.
PIR (Peak Information Rate)
The peak level in bits per second allowed for a frame relay connection.
PLCP (Physical Layer Convergence Protocol)
A protocol defined for use with Switched Megabit Data Service. Used on DS3 ATM trunks in the
BPX switch.
PLPP (Physical Layer Protocol Processor)
A custom VLSI processor used in the T3 ATM port interface of the BPX BNI card to handle the
coding and decoding of the PLCP bit structure. Functions handled by the PLPP include header
check sequence generation and checking, DS3 framing, and optional payload
scrambling/descrambling.
plesiochronous network
A network where there is more than one source of network timing. The multiples sources must
be operating at the same frequency but are not phase locked (synchronous) with each other.
port
Refers to a signal connection on a data back card that interfaces to a customer circuit or data
device. The number of ports on a card ranges from 1 to 8 depending on the particular card type.
PRI (Primary Rate Interface)
An ISDN interface to primary rate access. Primary rate access consists of a single D channel for
signalling and 23 (T1) or 30 (E1) B (bearer) channels for user data. A PRI is typically carried on
T1 or E1 facilities.
privilege level
A level between 1 and 6 that is assigned to each IPX command. Each operator is assigned a
privilege level by the system administrator. The operator may only access and execute commands
equal to or lower than his or her own privilege level. Level 1 is the highest and level 6 is the
lowest.
PVCs
Permanent Virtual Connections (circuits). Connections that are assigned but not connected until
data is sent, thereby not using bandwidth when idle.
