compressed in a secure manner before being encrypted with a private (secret) key under public-key cryptisystem.
MLPPP (Multilink Point-to-Point Protocol, also the PPP Multilink Protocol or MP)—is an Internet standards track protocol for a methyod of splittingm recombining, and sequencing datagrams across multiple logical data links, giving you additional bandwith- on-demand. Originally, MLPPP was used to combine two ISDN BRI channels into a single high-speed data path, but now is also used anywhere multiple PPP links connect two systems, including async links. This is done with new PPP options and protocols. Also knows as MPPP and PPP Multilink, MLPPP is an effective means of bonding channels for providing bandwith-on-demand.
modem—A communications device that enables a computer to transmit information over a telephone line. It converts the computer’s digital signals into analog signals to send over a telephone line and converts them back to digital signals at the receiving end. Modems can be internal and fit into an expansion slot, or external and connect to a serial port.
MP+(MultiLink Protocol Plus)—An extension to the PPP Multilink Protocol (MP) convered in IETF RFC 1717. MP+ is a new control protocol for managing multiple data links that are bundled by MP. Also called the Multichannel Protocol Plus or MPP.
MS-CHAP—Microsoft version of CHAP.
multilink—In point-to-point protocol, literally many links. A procedure used to route data packets over many links for increased bandwidth (e.g., two B-channels on a single BRI for 128 Kbps).
mux (multiplexer)—A device that merges several signals into one composite signal for transmission over a single medium or channel. A demultiplexer, built into most muxes, reverses the process at the receiving end.
N
nailed connection—A permanent or dedicated circuit of a previously switched circuit or circuits.
nailed-upcircuit—A semi-permanent circuit established through a circuit-switching facility for point-to-point connectivity.
NAK (negative acknowledgment)—A communications code used to indicate that a message was not properly received, or that a terminal does not wish to transmit. Contrast with ACK.
network—A group of computers connected by cables or other means and using software that enables them to share equipment, such as printers and disk drives to exchange information.
NI-1(National ISDN-1)—A physical standard to make all compliant ISDN lines appear the same. With ISDN-1 installed, additional costs are not incurred when changing from prestandard ISDN to standard ISDN. Most RBOCs now are moving to ISDN-1.
NI-2(National ISDN-2)—A physical standard subsequent to NI1. When tested and deployed, NI-2 will provide additional features and enhanced plug and play capabilities.
node—Any point within a network that has been assigned an address.
NT (network termination)—Devices that form the boundary between customer premise equipment and telephone company equip- ment. Two types of NTs are used: NT1 and NT2.
NT1 (Network TerminationType 1)—An interface device used in the BRI portion of ISDN to connect four-wire (S/T) ISDN devices to the two-wire (2BIQ U) IDN. It provides basic rate access in a 2B+D format with two 64 bps channels for voice, data, and video commu- nications. It also provides one 16 Kbps channel for packet-mode signalling, low-speed data and telecommunications services at the
OSI Layer 1 level. Similar in function to a DSU/CSU device.
NT2 (Network TerminationType 2)—A device at the customer premise (user) side responsible for the ISDN network connection and for functions such as multiplexing and switching (may be an intelligent device).
NTE (network terminating equipment)—A set of ISDN functions residing at the boundary of the IDN and the subscriber.
NUI (network user identification)—A unique alphanumeric number provided to dial-up users to identify them to packet-switched networks world-wide. The number is used for network access and billing.
O
off-hook—The condition of a device that has accessed a phone line (with or without using the line). In modem use, this is equivalent to a telephone handset being picked up. Dialing and transmission are allowed, but incoming calls are not answered.
on-demanddialing—A cost-saving feature of ISDN that sets up, transfers, and then closes a call only when the ISDN device detects a data packet addressed to the remote network, but will not perform setup/transfers of just administrative (non-user data) packets.
out-of-bandsignaling—A system that uses a separate communications channel or frequency outside the voice band for signaling. Modern systems use a separate channel, either TDM or virtual. SS7 uses messages for signaling that are carried on signaling links distinct from voice channels. ISDN uses messages for signaling that are carried on the
D-channel distinct from the voice carried on the B-channels. Frame Relay and ATM use messages that are carried on a separate virtual connection reserved for signaling.
on-hook—The condition of a device which has not accessed a phone line. In modem use, this is equivalent to a telephone handset that has not been picked up. In other words, it can receive an incoming call.
P
packet data—Packet-mode calls.
packet mode—The switching of chunks of information for different users using statistical multiplexing to send them over the same transmission facility. ISDN packet mode capabilities are based on the ITU-TSS Recommendation X.25 procedures.
PAP(Password Authentication Protocol): (RFC1334)
parity bit—An extra bit attached to each byte of sync—hronous data used to detect errors in transmission.
PBX (private branch exchange)—A telephone exchange located on the customer’s premises. The PBX provides a circuit switching facility for tlephone extension lines within the building, and access to the public telephone network. See also exchange.
P-channel(PCHAN)—The ISDN physical channel identification; contrast logical channel or virtual channel.
PDN (public data network)—A packet-switched network that is available to the public for individual (subscriber) use. Typically, controlled by a government or a national monopoly.
port—A location for input or output data exchange. Computers, muxes, etc. have ports for various purposes.
PPP(Point to Point Protocol)—A protocol that lets a computer user access a TCP/IP address using an ISDN terminal adapter or a high- speed modem over a standard telephone line.
PRI (Primary Rate Interface)—One
of two forms of ISDN service. PRI provides 23 64 Kbps B-channels for video, voice or data, and one 64 Kbps D-channel for control
