IBM International ISDN, Руководство пользователя

Страница: 205 / 244

Appendix C: A Brief ISDN Glossary
ISDN PC Card – 17 Appendix C: A Brief ISDN Glossary 205
PPP The Point-to-Point Protocol. A TCP/IP protocol
used in the dial-up networking environment. PPP
works on the OSI layers 1 and 2. It is a full-duplex
protocol that can be used on various physical me-
dia, including twisted pair or fiber optic lines, or
satellite links. It uses a variant of High Speed Da-
ta Link Control (HDLC) for packet encapsulation.
PPTP Point-to-Point Tunneling Protocol. A variation of
the PPP protocol. It is a protocol (set of communi-
cation rules) that allows corporations to extend
their own corporate network through private “tun-
nels” over the public Internet. In effect, a corpora-
tion uses a wide-area network as a single large lo-
cal-area network. Companies no longer need to
lease their own lines for wide-area communica-
tion, but can securely use the public Internet. This
kind of interconnection is known as a virtual pri-
vate network (VPN).
PRI See Primary rate interface.
Primary-ate
interface (PRI) Access to the ISDN network comes in two different
flavors, known as basic-rate and primary-rate ac-
cess. The primary-rate interface is similar to an E1
line. The total data rate is 2.048 Mbit/s. However,
the PRI provides 30 ISDN B channels and one D
channel, all operating at 64 kbit/s. PRIs can be
used in large RAS environments.
S
0
interface Another name for the BRI interface in Europe,
where the telephone company generally provides
the NT device. For BRIs in point-to-multipoint con-
figuration, the S
0
interface is a four-wire data bus.
S
2M
interface Another name for the PRI in Europe.
S/T interface The European reference point for connecting an
ISDN terminal equipment to the ISDN network.
This interface is provided by the NT-1, which in Eu-
rope is furnished by the telephone company.
Glossary