3Com 4005 Installation And Maintenance Manual page 74

74 G
LOSSARY
out-of-band
packet
protocol
PDU
QoS
RIP
RJ-45 connector
router
RS-232 serial port
SC connector
server
SNMP
spanning tree
Transmission of information, for example, device management messages, over a
medium that is not accessed by network users.
Any logical block of data that is sent over a network. It contains a header that
consists of control information such as senders, receivers, and error control data,
as well as the message itself.
A set of rules for communicating between computers. The rules dictate format,
timing, sequencing, and error control.
Protocol Data Unit. A unit of data that is specified in a layer protocol and consists
of protocol control information and layer user data.
Quality of Service. Term to describe delay, throughput, bandwidth, and so forth of
a virtual connection; a measure of the service quality that is provided to a user.
Routing Information Protocol. The RIP protocol seeks to find the shortest route to
another device by minimizing the distance-vector, or hop count, which serves as a
rough estimate of transmission cost. RIP-2 is a compatible upgrade to RIP. It adds
useful capabilities for subnet routing, authentication, and multicast transmissions.
A connector that holds up to eight copper wires and is similar in design to the
RJ-11 standard telephone connector. RJ-45 connectors are often featured on
Ethernet devices.
A device that connects two dissimilar networks by selectively forwarding messages
between them. A router operates at Layer 3 in the OSI Reference Model. A router
is similar in operation to a Layer 3 switch.
A port that changes the parallel arrangement of data within computers to the
serial (one after the other) form used on data transmission links. This type of port
can be used for local management access of a network device.
A fiber-optic cable connector that uses a push-pull latching mechanism similar to
common audio and video cables. For bi-directional transmission, two fiber cables
and two SC connectors are generally used.
A computer that provides clients with file storage, software applications, or other
network services. One server is usually shared by multiple users.
Simple Network Management Protocol. A protocol that was originally designed to
be used in managing TCP/IP internets is now the de facto standard for managing
LANs. A network manager uses a remote PC or UNIX workstation to operate
SNMP-based software that communicates with network devices that have SNMP
agents built into them. These agents collect information about network activity
and device status and send it back to the workstation.
A technique that detects network loops, or multiple paths to the same destination,
and logically blocks the redundant paths until they are needed. One of the most
popular examples of the spanning tree approach is included in the IEEE 802.1D
standard for MAC bridges. Bridges that support the Spanning Tree Protocol work
with each other to ensure that only one route exists between any two LANs. This
action prevents a debilitating network condition known as a broadcast storm,
where the same packets are repeated and multiplied to the point where LAN
bandwidth is totally clogged and legitimate traffic cannot get through.