g-6
Glossary
PVC Abbreviation for permanent virtual circuit, a virtual circuit that is
permanently available. The only difference between a PVC and a
switched virtual circuit (SVC) is that an SVC must be reestablished
each time data is to be sent. Once the data has been sent, the SVC
disappears. PVCs are more efficient for connections between hosts
that communicate frequently.
router The central switching device of the Internet, corporate Intranets, and
WANs. A router is a highly intelligent device that connects like and
unlike local area networks. It connects to Metropolitan Area
Networks such as X.25, Frame Relay, and ATM. Routers are
protocol sensitive, typically supporting multiple protocols.
RS-232 A set of standards developed by the EIA (Electrical Industries
Association) that defines the mechanical and electrical
characteristics for connecting DTE and DCE communications
devices. It defines what the interface does, circuit functions and their
corresponding connector pin assignments. The most commonly used
RS-232 interface is ideal for the data transmission range of up to 20
Kbps for up to 50 feet.
SAN See Storage Area Networking.
SFP See Small Form-Factor Pluggable
Simple Network
Management Protocol
A common method by which network management applications can
query a management agent using a support MIB. SNMP operates at
the OSI Application layer.
Small Form-Factor
Pluggable
Optical modular transceivers that are hot-swappable. They offer
high speed and physical compactness, and are designed for use with
small form factor connectors.
SNMP See Simple Network Management Protocol.
SONET Synchronous Optical Network, a standard for connecting fiber-optic
transmission systems. SONET was proposed by Bellcore in the
middle 1980s and is now an ANSI standard. SONET defines
interface standards at the physical layer of the OSI seven-layer
model. The standard defines a hierarchy of interface rates that allow
data streams at different rates to be multiplexed. SONET establishes
Optical Carrier (OC) levels from 51.8 Mbps (about the same as a T-3
line) to 2.48 Gbps. Prior rate standards used by different countries
specified rates that were not compatible for multiplexing. With the
implementation of SONET, communication carriers throughout the
world can interconnect their existing digital carrier and fiber optic
systems. The international equivalent of SONET, standardized by
the ITU, is called SDH.
Static Route A route that is manually entered into a routing table. Static routes
take precedence over routes chosen by dynamic routing protocols.
See Static Routing.