Alcatel-Lucent 9500 MXC, Руководство пользователя

Страница: 890 / 916

16 Alcatel-Lucent
Oscillator
An electronic circuit designed to produce an ideally stable alternating voltage or current.
OSI
Open Systems Interconnection
OSPF
Open Shortest Path First
OSPF (Open Shortest Path First) is a router protocol used within larger internal networks in preference to the
Routing Information Protocol (RIP), an older routing protocol. Like RIP, OSPF is designated by the Internet
Engineering Task Force (IETF) as one of several Interior Gateway Protocols (IGPs). Using OSPF, a host that
obtains a change to a routing table or detects a change in the network immediately multicasts the information
to all other hosts in the network so that all will have the same routing table information. Unlike the RIP in which
the entire routing table is sent, the host using OSPF sends only the part that has changed. With RIP, the routing
table is sent to a neighbor host every 30 seconds. OSPF multicasts the updated information only when a change
has taken place. Rather than simply counting the number of hops, OSPF bases its path descriptions on "link
states" that take into account additional network information. OSPF also lets the user assign cost metrics to a
given host router so that some paths are given preference. OSPF supports a variable network subnet mask so
that a network can be subdivided. RIP is supported within OSPF for router-to-end station communication. Since
many networks using RIP are already in use, router manufacturers tend to include RIP support within a router
designed primarily for OSPF.
OSS
Operations Support System
PA
Power Amplifier
PAM
P
ulsed Amplitude Modulation
Path
A radio path refers to the path travelled by radio waves between transmitting and receiving devices.
PC
Personal Computer
PCA
Printed Circuit Assembly
PCB
printed circuit board
PCM
Pulse Code Modulation
Modulation in which a signal is sampled, quantized and then digized for transmission over a common
transmission medium.