Cisco Systems 8600 Series Partially-interleaved EIA, PBX private branch exchange, Port, PVCs

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.

E-14Cisco BPX 8600 Series Reference