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·
An Ethernet physical interface defined by IEEE
and supported by LightStream with the use of an external transceiver.
Uses thin 50-Ohm baseband coaxial cabling. Two 15-pin AUI ports on each
Ethernet access card support connections to 10Base2 transceivers.
·
An Ethernet physical interface defined by IEEE
and supported by LightStream with the use of an external transceiver. Uses
standard (thick wire) 50-Ohm baseband coaxial cabling. Two 15-pin AUI ports on
each Ethernet access card support connections to 10Base5 transceivers.
·
An Ethernet physical interface defined by IEEE
and supported by LightStream. Uses unshielded twisted pair cabling. All eight
ports on an Ethernet access card support 10Base-T connections.
· An I/O card located at the back of the LightStream chassis. Together with their associated line cards, access cards provide data transfer services for the switch using physical interfaces such as OC-3c. A LightStream switch can have up to 10 access cards.
·
· Access card types include low-speed (jumper-settable to V.35 or RS-449/X.21), T3, E3/PLCP, E3/G.804, Ethernet, FDDI, OC-3c, and an NP access card to provide Ethernet connectivity for network management.
·
·
American National Standards Institute, a
voluntary organization that develops positions for the United States in
international standards organizations such as ITU-T. ANSI helps develop
international network protocols and standards, including ATM, and US standards
such as T1.
·
Address resolution protocol. Uses an IP
network address to determine a physical hardware address (i.e., a MAC address).
LightStream's implementation of ARP conforms to RFC 826.
·
The communications technology on which the
LightStream 2020 is based. ATM is an international standard for cell relay.
Traffic in an ATM network consists of 53-byte cells designed to take advantage
of high-speed transmission media such as T3, E3 and SONET. ATM's fixed-length
cells allow cell processing to occur in hardware, reducing transit delays.
·
An international organization that develops
implementation agreements for ATM technology. The Forum expands on official
standards developed by ANSI and ITU-T, and develops implementation agreements
in advance of official standards.
·
ATM user-network interface. The LightStream
edge interface used for connections to non-LightStream ATM devices. ATM UNI
offers users direct access to the ATM network's cell relay service.
·
LightStream configuration data is structured
as a series of attributes, or parameters, that you can set using the
configuration program or CLI commands. Attributes define the characteristics of
database objects such as chassis, cards, ports, virtual circuits and custom
filters.
·
Attachment unit interface. The interface
between a station on an Ethernet and its transceiver. LightStream Ethernet
access cards have two AUI ports. See also transeiver.
·
The traffic-bearing capacity of the lines and
switches in a network.
·
The process of assigning bandwidth to the
users and applications served by a network. In a LightStream network, bandwidth
allocation involves assigning priority to different flows of traffic based on
how critical and how delay-sensitive they are. If the network becomes
congested, lower-priority traffic can be dropped.
·
The LynxOS Bourne-again shell. This UNIX shell
is presented when you log into a LightStream switch as root or fldsup; its
prompt is bash# (for root) or bash$ (for fldsup).
·
The minimal configuration information entered
when a new LightStream system is installed, including IP addresses, the date,
and parameters for at least one trunk line. The basic configuration enables the
node to receive a full configuration from the NMS.
·
A cooling device. Each LightStream chassis
contains two blowers; one is accessible from the front of the chassis, one from
the rear. Blowers are temperature-controlled; under normal operating
conditions, they slow down after start-up to reduce noise.
·
Bridge protocol data unit. As part of the
spanning tree protocol, these frames are sent out at a configurable interval to
exchange information among bridges in the network.
· A device that links two networks that use the same communications method and addressing structure (i.e., the same protocol). Bridges function at the data link level (level 2) of the OSI reference model. LightStream bridging conforms to the IEEE 802.1d standard. The
· following 802.1d bridging services are provided by the LightStream switch:
·
bridge forwarding
·
Each bridging service is described in an entry
of its own.
·
The bridge forwarding process uses the entries
in the filtering database to determine if frames with a given MAC destination
address can be forwarded to a given port or ports. LightStream bridging
implements bridge forwarding, which is defined in the IEEE 802.1d standard.
·
A bridge maintains a filtering database
consisting of static entries. Each static entry equates a MAC destination
address with a LightStream port that can receive frames with this MAC
destination address and a set of LightStream ports on which the frames can be
transmitted. LightStream bridging implements bridge static filtering, which is
defined in the IEEE 802.1d standard.
·
A data link broadcast is a frame with a MAC
destination address that consists of all 1's. These frames are received by all
end stations on an extended LAN.
·
The traffic management mechanism that
determines whether the network can offer a path with sufficient bandwidth for a
requested VCC.
·
A technique used to maintain framing on some
medium-speed edge and trunk interfaces. You can use the configurator or the setsnmp
command in the CLI to turn this feature on or off.
·
Cell line card. In conjunction with an access
card, supports up to two OC-3c edge ports or one OC-3c trunk port.
·
LightStream's command line interface. CLI runs
on NPs and Sun SPARCstations; it lets you monitor and control the LightStream
network. CLI is introduced in the LightStream 2020 Operations Guide,
and CLI commands are described in the LightStream 2020 Command and
Attribute Reference Guide.
·
Cell loss priority. A CLP bit in each ATM
cell's header determines how likely it is the cell will be dropped if the
network becomes congested. Cells with CLP=0 are insured traffic, which is
unlikely to be dropped. Cells with CLP=1 are best effort traffic, and may be
dropped in congested conditions, freeing up resources to handle higher-priority
CLP=0 traffic.
·
A file of attribute settings that you create
using the LightStream configurator. The global database holds configuration
information for the entire LightStream network and is stored on the network
management station. Each switch also has a file containing just its own
configuration information, called a local database. Configuration data includes
definitions of chassis, cards, ports, virtual circuits, and the attributes that
describe them.
·
The mechanism by which the LightStream network
controls traffic entering the network to minimize delays. In order to use
resources most efficiently, lower-priority traffic is discarded at the edge of
the network if conditions indicate that it cannot be delivered.
·
·
LightStream's intelligent traffic management
scheme, which includes congestion avoidance, traffic shaping, and traffic
policing, allows links to operate at high levels of utilization by scaling back
lower-priority, delay-tolerant traffic at the edge of the network when
congestion begins to occur.
·
Cells per second.
connect to an external DSU/CSU on a low-speed line for purposes of monitoring
and control, or
display statistics on a medium-speed line's internal DSU/CSU.
·
A bridge's ability to allow or discard frames
of traffic based on such criteria as their source address, destination address,
or protocol. Custom filtering criteria are defined on a per-port basis. In a
LightStream network, you define custom filters using the configurator.
·
·
(1) The device at the network end of the user-to-network
interface. The DCE provides a physical connection to the network, forwards
traffic, and provides a clocking signal used to synchronize data transmission between
DCE and DTE devices. (2) The port for connecting a DTE into a data network. The
DCE here can be a LightStream interface or modem.
·
The device at the user end of the
user-to-network interface; usually a processor. A DTE connects to a data
network via data circuit-terminating equipment (DCE), and typically uses
clocking signals generated by the DCE.
·
·
A chassis, card or port as defined in a
LightStream configuration database. Database objects have associated attributes
that describe them.
·
·
A LightStream disk assembly is composed of a
120-Mbyte hard disk drive, a 3.5-inch floppy disk drive, and a disk power
supply. The hard disk holds system and application software and configuration
data. The floppy drive is used for loading software. Each NP in a chassis has
its own disk assembly.
·
·
Data link connection identifier. Frame relay
PVCs are identified by DLCIs. A DLCI in a LightStream network identifies a
unique circuit between two ports.
·
·
Digital signal level 1, a wide-area digital
transmission scheme that carries data at a rate of 1.544 Mbps. DS1 lines can be
leased for private use from common carriers. In conjunction with an external
DSU/CSU, LightStream can use DS1 for low-speed trunks and edge connections.
(DS1 is also referred to as T1.)
·
· Digital signal level 3, a wide-area digital transmission scheme that carries data at a rate of 44.736 Mbps. DS3 lines can be leased for private use from common carriers. LightStream uses DS3 for medium-speed trunks and edge connections. (DS3 is also referred to as T3.)
·
·
Data service unit/channel service unit. A
device that adapts the physical interface (such as V.35) on a bit serial device
(such as a LightStream frame relay or frame forwarding DTE) to a network
interface (such as T1 or E1). Each DSU/CSU serves one LightStream I/O port.
·
· A wide-area digital transmission scheme used predominantly in Europe that carries data at a rate of 2.048 Mbps. E1 lines can be leased for private use from common carriers. LightStream can use E1 for low-speed trunks.
·
·
A wide-area digital transmission scheme used
predominantly in Europe that carries data at a rate of 34.368 Mbps. E3 lines
can be leased for private use from common carriers. LightStream uses E3 for
medium-speed trunks and ATM UNIs.
·
· Edge card control process. Each ECC process on the NP performs per-card processing for an edge card, including protocol management (ATM connection management) and media-specific (Ethernet and FDDI) management tasks, internetworking operations such as packet forwarding and filtering, and network management tasks.
·
· A line card configured to communicate with devices outside the ATM network. LightStream edge cards offer frame forwarding, frame relay, Ethernet, FDDI, OC-3c, and ATM UNI interfaces.
·
·
A non-LightStream entity such as a LAN
segment, host, or router that connects to the LightStream network via an edge
card. Edge devices send and receive the data that passes through the
LightStream network.
·
·
Electrically erasable, programmable read-only
memory. Two EEPROM chips on the LightStream midplane store the node's chassis
ID, modem information and other data, which you can edit using TCS commands.
Flash EEPROMs on the function cards store firmware that is periodically
upgraded by LightStream software releases, but cannot be edited.
·
·
The device at which a virtual circuit begins
or ends. (This term may refer to an edge device, to a specific port on a
LightStream switch, or (most often) to the LightStream switch as a whole.)
·
· A widely used LAN protocol. The LightStream Ethernet implementation, which conforms to IEEE's 802.3 CSMA/CD network standard, is compatible with 10Base-T cabling and can be connected to 10Base2 and 10Base5 cabling via transceivers. It operates at 10 Mbps.
·
· Traffic in excess of the insured rate for a given call. (Specifically, the excess rate equals the maximum rate minus the insured rate.) Excess traffic is delivered only if network resources allow; it may be discarded if the network is congested.
·
· Fiber distributed data interface, a LAN standard specified by ANSI X3T9.5. FDDI transmits data over fiber optic cable and supports up to 100 Mbps of bandwidth. The LightStream FDDI implementation uses SMT 7.3.
·
·
One of the four default user accounts that are
created in the factory on each LightStream switch. The fldsup account is for
use by LightStream field service personnel. Its default interface is the bash
shell.
·
·
A method used to distribute certain control
information and some LAN packets among interconnected LightStream switches.
Flooding of control information within the LightStream network occurs when a
switch receiving new information on a trunk port "floods" or
retransmits the information on all of its other trunk ports. Bridge flooding is
the retransmission of a datagram on all bridge interfaces of the LightStream
switch except the receiving port.
·
·
A stream of data travelling between two
endpoints across a network (for example, from one LAN station to another). One
circuit can support multiple flows.
·
·
A LightStream interface that allows any
traffic based on HDLC or SDLC frames to traverse the LightStream network. FF
circuits are port-to-port, and only one circuit (PVC) is allowed between a pair
of ports. FF is supported by the low-speed interface module, which offers V.35,
RS-449, or X.21 physical interfaces.
·
·
An industry standard switched data link
protocol that handles multiple data streams (VCs) using HDLC encapsulation
between connected devices. FR is supported by LightStream's low-speed interface
module, which offers V.35, RS-449 or X.21 physical interfaces.
·
·
Field-replaceable unit. A component that can
be removed and replaced in the field. LightStream FRUs include switch cards,
function cards, access cards, power trays, blowers, disk assemblies, and the
midplane.
·
·
From switch unit. The subsystem on each line
card that accepts cells from the switch card, verifies their checksums, and
passes them to the reassembly unit. The FSU selectively drops cells if the
network becomes congested.
·
·
File transfer protocol. An application
protocol from the IP family that controls the transfer of files from one
network host to another. FTP is defined in RFC 959.
·
·
A line card or an NP card in a LightStream
switch.
·
·
The framing standard used by the G.804 version
of LightStream's E3 access card. Defines the mapping of ATM cells into the
physical media (E3). The standard is CCITT Recommendation G.804 (1993).
·
·
Gigabits per second.
·
·
Global information distribution, a process
that runs on every NP in the LightStream network. GID maintains a database and
keeps nodes in the network apprised of changes in topology such as ports,
cards, and nodes being added or removed, and trunks going up or down. This
information is supplied by the ND process. GID is sometimes referred to as
GIDD, the global information distribution daemon.
·
·
A protocol for placing packets on a serial
line, with frame characters and checksums. The ISO layer 2 (data link) protocol
for X.25 networks, HDLC is based on IBM's SDLC. LightStream's frame forwarding
interface handles HDLC and SDLC traffic.
·
·
When data travels across the network, it may
pass through many LightStream switches. The journey between each pair of
switches in the path is known as a hop.
·
·
Institute of Electrical and Electronics
Engineers, a professional organization whose activities include the development
of communications standards.
·
· The largest burst of data above the Insured Rate that will be temporarily allowed on a PVC but will not be tagged (CLP bit set to 1) by the traffic policing function for dropping in the case of network congestion. Specified in bytes or cells.
·
· The long-term data throughput, in bits or cells per second, that the LightStream network commits to support under normal network conditions. The insured rate is 100% allocated: the entire amount is deducted from trunk bandwidth along the path of the circuit.
·
· Traffic within the insured rate specified for the PVC. This traffic should not be dropped by the network.
·
·
The combination of a line card and access card
that together allow you to connect a LightStream switch to other devices.
·
· The basic data transport mechanism used between Internet hosts and gateways. It offers a datagram (connectionless) internetwork service that provides features for addressing, type-of-service specification, fragmentation and reassembly, and security. The Internet Protocol suite is often referred to as TCP/IP, because TCP and IP are the two most prominent elements in it. IP is defined in RFC 791.
·
·
An IP address is a 32-bit quantity that
belongs to one of five classes (A, B, C, D, or E). The address consists of a
network number, a subnetwork number, and a host number. The network and
subnetwork numbers together are used for routing, while the host number is used
to address an individual host within the network/subnetwork. A subnet mask is
used to extract network and subnetwork from the IP address by logically ANDing
the IP address with the subnet mask. (For more information, see Appendix B of
the LightStream 2020 Installation and Troubleshooting Manual.)
·
·
Also I-TSS, ITU-TSS, and ITU-TS; the
International Telecommunications Union Telecommunication Standardization
Sector. ITU-T develops worldwide standards for telecommunications technologies,
including ATM. ITU-T has produced ATM standards for the ATM layer, AAL5, the
UNI, physical layer mappings, signalling, and more. ITU-T, formerly known as
CCITT, operates under the umbrella of the United Nations.
·
·
An electrical switch consisting of a set of
pins and a connector that can be attached to the pins in two different ways.
Jumpers on LightStream's low-speed access card control the type of interface
(V.35 or RS-449/X.21) presented by I/O ports.
·
·
Kilobytes.
·
·
Kilobits.
·
·
Kilobits per second.
·
·
Local area network. A high-speed, low-error
data communications facility that operates over distances up to a few thousand
meters. LANs connect workstations, peripherals, terminals, and other devices in
a building or in a geographically limited area. LAN standards specify cabling
and signalling at layers 1 (physical) and 2 (data link) of the OSI network
model. Ethernet, token ring and FDDI are widely used LANs.
·
·
Line card control process. Among other things,
the LCC process establishes VCCs, maintains the link management protocol for
the line card, and continually monitors line quality on each trunk using the
trunk up-down protocol. An instance of the LCC runs on the NP for each LSC,
MSC, and CLC.
·
·
Light-emitting diode. LEDs indicate the status
of cards in the LightStream chassis.
·
·
Together with its access card, a line card
provides I/O services for the LightStream switch. Cell line cards, medium-speed
line cards and low-speed line cards can be configured as edge or trunk cards.
Packet line cards can be configured only as edge cards. Edge cards provide
lines to devices outside the ATM network and trunk cards provide lines to other
switches inside the network.
·
·
Logical link control. A sublayer of the data
link layer that defines the multiplexing fields and gives optional types of
service that can be run over IEEE 802 LANs.
·
·
Local management interface. A frame relay
protocol for getting the status of frame relay circuits from attached frame
relay devices. In a LightStream network, external devices receive information
from LightStream switches.
·
·
A bridge's ability to filter out (drop) frames
of local traffic--that is, frames whose MAC source and destination addresses
are located on the same interface of the bridge, and therefore do not need to
be forwarded across the bridge. LightStream bridging implements local traffic
filtering, which is defined in the IEEE 802.1d standard.
·
·
Low-speed line card. In conjunction with an
access card, supports eight trunk or edge (frame relay or frame forwarding)
ports at individual port speeds up to 3.584 Mbps, or an aggregate rate of 6
Mbps per line card.
·
·
The real-time, UNIX-like operating system that
runs on LightStream NPs. Lynx commands are described in the LightStream 2020
Command and Attribute Reference Guide. LynxOS is a product of Lynx
Real-Time Systems, Inc.
·
·
Medium access control. A sublayer of the data
link layer concerned with access to the shared media of each type of LAN.
·
·
Physical shared media address of a LAN device.
MAC addresses are 6 bytes long. They are controlled by IEEE.
·
·
The service that characterizes a learning
bridge, in which the source address of each received packet is stored. Future
packets for that address are forwarded only to the bridge interface on which
that address is located. Packets for unrecognized addresses are forwarded to
every bridge interface. This scheme helps minimize traffic on the attached
LANs. LightStream bridging implements MAC address learning, which is defined in
IEEE 802.1d.
·
· Specifies the largest burst of data above the Insured Rate that will temporarily be allowed on the PVC but will not be dropped at the edge by the traffic policing function, even if it exceeds the Maximum Rate. This amount of traffic will be allowed in only temporarily; on average, the traffic source needs to be within the Maximum Rate. Specified in bytes or cells.
·
· The maximum insured plus uninsured data throughput rate that the LightStream network will attempt to deliver on a given virtual circuit. The uninsured data may be dropped if the network is congested. This throughput, which cannot exceed the media rate, is the highest that the virtual circuit will ever deliver. MR is measured in bits or cells per second.
·
·
Megabyte.
·
·
Megabit.
·
·
Megabits per second.
·
·
Management information base. A database of
network management information used and maintained by SNMP. Objects in the MIB
are organized as a tree structure; their values can be changed or retrieved
using SNMP commands. For more information, refer to Chapter 4 of the LightStream
2020 Command and Attribute Reference Guide.
·
·
Master management agent. The MMA runs on the
NP; it is the SNMP agent for the NP, and translates between an external network
manager using SNMP and the internal switch management mechanisms.
·
·
Modulator/demodulator. A device that modulates
digital signals onto an analog carrier (line) at the transmitting site and
performs the reverse process at the receiving site. Modems allow data to be
transmitted over voice-grade telephone lines. Each LightStream chassis has a
modem port for connecting to an external modem. The modem port is for remote
monitor and control of the node; it's particularly useful if the node becomes
isolated from the rest of the network.
·
·
Medium-speed line card. In conjunction with an
access card, supports two trunk or edge (ATM UNI) ports at data rates up to T3
or E3.
·
·
Neighborhood discovery, a process that runs on
every NP in the LightStream network. For call routing purposes, every node in
the network needs to know about changes in network topology, such as trunks and
ports going up or down. ND learns about such changes at the chassis level and
forwards this information to the GID process, which sends the information
throughout the network. ND is sometimes referred to as NDD, the neighborhood
discovery daemon.
·
·
A person responsible for the operation,
maintenance, and management of a network.
·
·
A person who performs routine monitoring and
control of a network. Tasks include reviewing and if necessary responding to
traps, monitoring throughput, configuring new circuits and resolving problems.
·
·
Network management system. A device from which
you can configure and manage a network. The NMS for a LightStream network must
be a Sun SPARCstation running LightStream management software. NMS requirements
are listed in the LightStream 2020 Site Planning and Cabling Guide.
·
·
Network-to-network interface. NNI is concerned
with the transfer of information between network nodes belonging to two
different frame relay or ATM networks.
·
·
An endpoint of a network connection, or a
junction common to two or more lines in a network. Nodes can be processors,
controllers, or workstations. Nodes, which vary in routing and in other
functional capabilities, can be interconnected by links and serve as control
points in the network. Each LightStream chassis is one node.
·
·
The network processor card is the LightStream
2020 system's main computational and storage resource. Each LightStream switch
has one or two NPs. The second card, if present, serves as a backup to the
first. Each NP is associated with a floppy disk drive for loading software and
a hard disk drive for storing software and configuration data. Each NP also has
an access card that provides an Ethernet port.
·
·
The NP module includes the NP card, NP access
card, and disk assembly.
·
·
One of the four default user accounts that are
created in the factory on each LightStream switch. The npadmin account is for
privileged users. Its default interface is the CLI.
·
· Optical carrier 3. A physical protocol used by LightStream's OC-3 access cards to put STS frames onto a 155.52-Mbps fiber line. (An STS-3c signal carried on an OC-3 physical medium is often referred to as OC-3c.) LightStream supports both single mode and multimode OC-3 fiber interfaces.
·
·
One of the four default user accounts that are
created in the factory on each LightStream switch. The oper account is for
general users. Its default interface is the CLI.
·
·
Organizationally unique identifier. The three
octets assigned by the IEEE in a block of 48-bit LAN addresses.
·
·
A WAN device that routes packets along the
most efficient path and allows a communications channel to be shared by
multiple connections.
·
·
The full name of a LynxOS (or UNIX ) file or
directory, including all directory and subdirectory names. Consecutive names in
the path are separated by slashes (/), as in /usr/app/base/config.
·
·
Packet line card. In conjunction with an
access card, supports up to eight Ethernet or two FDDI edge ports.
·
·
Physical layer convergence protocol. Defines
the mapping of ATM cells into physical media such as T3 and E3.
·
·
Power-on self test. A set of hardware
diagnostics that runs on each NP, switch card and line card whenever the card
is powered up. If the fault (FLT) LED on a card is on, the card is not working
and may have failed POST.
·
·
A feature that allows faulty components of a
LightStream switch to be diagnosed, removed and replaced while the rest of the
switch continues to operate normally.
·
·
A LightStream switch can have one or two bulk
power trays; both are accessible from the rear of the chassis. In a redundant
system the two power trays load-share, but either can power the whole system.
LightStream offers two power options, one for sites with AC power and one for
sites with DC power.
·
·
Permanent virtual circuit. A VCC created by a
network operator using the configurator. For each PVC, you specify endpoints, a
VCI or DLCI number, and bandwidth allocation attributes such as insured and
maximum data rates. PVCs remain in place until they are explicitly deleted. All
VCCs for LSC, MSC, and CLC edge cards are PVCs.
·
·
A fully redundant LightStream system has two
network processor cards with disks, two switch cards, and two bulk power trays.
The power trays load-share; the extra NP and switch cards serve as hot spares
and become active automatically if needed. A partially redundant system has two
of some subsystems but not others; for example, it might have two NPs, one
switch card, and one power tray.
·
·
Request for comments. RFCs are published by
the Internet Engineering Task Force (IETF) to define internetworking protocols
and standards.
·
·
One of the four default user accounts that are
created in the factory on each LightStream switch. The root account is for use
by the system or network administrator only. Its default interface is the bash
shell.
·
·
LightStream's LAN/WAN internetworking
architecture provides bridging services (autolearning and spanning tree),
custom filtering, broadcast storm control, frame relay service, and frame
forwarding service.
·
·
Radio standard 449. A physical and electrical
OSI layer 1 (physical) interface developed by the Electronic Industries
Association. The standard is EIA-449. LightStream's low-speed interface modules
can provide up to eight RS-449 ports each.
·
·
Memory on a LightStream node whose contents
includes the configuration data for that node. Run-time memory is accessed
while the node operates.
·
·
Service access point. A field defined in IEEE
802.2 that is part of an address specification. Thus, the destination plus the
destination SAP (DSAP) define the recipient of a packet, similarly for the
source SAP (SSAP).
·
·
To limit surges that congest the network,
bursts of user traffic are buffered on an edge card and then sent into the
network in regulated amounts. (Also known as smoothing and metering.)
·
·
The station management task that controls FDDI
interfaces. LightStream FDDI interfaces implement SMT 7.3.
·
· Subnetwork access protocol SAP. A particular value of SAP reserved by IEEE 802.2 for all protocols whose SAP value is not globally assigned.
·
·
Simple network management protocol. The
network management protocol used by LightStream, and the management protocol
most often associated with TCP/IP systems. It provides tools for monitoring and
controlling network devices and for managing configuration, statistics
collection, performance, and security. The LightStream configurator uses SNMP
to send configuration data from the NMS to each switch in the network.
·
·
A scheme that enables SNMP devices to validate
requests from sources such as the NMS or the CLI. A LightStream switch is
configured to recognize several communities. Each community has a name and an
associated access privilege, which is either read-only or read-write. A
LightStream switch responds only to SNMP requests that come from members of
known communities and that have the access privileges required for that
request. You can set the community used by CLI for its requests using the command
set snmp community <name>.
·
· Synchronous optical network. The overall US specifications for the range of telco synchronous optical networking, including many transmission formats and management systems.
·
· Enables a learning bridge to dynamically work around loops in a network topology. Without spanning tree, a learning bridge can't tolerate loops in the network because loops can cause the bridge to receive the same packets on several interfaces, which makes the learning process impossible. Spanning tree bridges exchange BPDU messages to detect loops, then remove the loops by shutting down selected bridge interfaces. LightStream bridging implements the spanning tree protocol, which is defined in the IEEE 802.1d standard.
·
·
LightStream's suite of SNMP-based network
management tools includes a configuration program and a monitoring program with
easy-to-use graphical user interfaces, as well as a command line interface
(CLI).
·
· Synchronous transport signal, level 3, concatenated. A SONET format used by LightStream that specifies the frame structure for the 155.52-Mbps lines used to carry ATM cells.
·
· A convention whereby a network administrator can arbitrarily divide an IP network into multiple subnetworks. Subnets provide a multilevel hierarchical/ routing structure. This concept allows an internet to be shielded from the addressing complexity of attached networks.
·
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Handles communication between other cards in
the LightStream switch. Each LightStream switch has one or two switch cards;
the second card, if present, serves as a backup to the first.
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The IBM-defined network architecture that
allows a variety of IBM devices to exchange data.
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ATM cells whose CLP bits are set to 1. If the
network is congested, tagged traffic may be dropped to ensure delivery of
higher-priority (CLP=0) traffic.
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Test and control system. An independently
powered subsystem used to initialize, monitor and troubleshoot LightStream
hardware. It consists of a hub residing on the switch card and slaves on NPs
and line cards.
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A member of the IP family of protocols, telnet
is used for remote terminal connection in a LightStream network. It enables you
to log in to a remote system and use its resources just as if you were
connected directly (locally) to the system. Telnet is defined in RFC 854.
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At the edge of the LightStream network,
traffic policing discards traffic exceeding the total admissible bandwidth for
a given connection. Traffic that falls outside the committed rate for the
connection is tagged by setting its CLP bit to 1; this traffic may be discarded
en route if congestion develops. (Also known as rate enforcement, usage
parameter control (UPC), admission control, and permit processing.)
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On an Ethernet, a device that lets a station
transmit and receive data. The transceiver provides the interface between the
station's AUI port and the common medium of the Ethernet. The transceiver may
be built into the station, or it may be a separate device. Transceivers are
also known as MAUs, medium access units.
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Connects networks using dissimilar media.
LightStream's translation bridging service, for example, connects Ethernet and
FDDI. The implementation conforms to the IEEE 802.1d standard.
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Each LightStream internal type of service
correlates to a relative priority in queues in the LightStream network. This
priority determines which traffic is serviced first in the case of contention
for a network resource. (Also known as transfer priority and forwarding
priority.)
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Connects networks of the same media type.
LightStream's transparent bridging service, for example, connects Ethernet to
Ethernet and FDDI to FDDI. The implementation conforms to the IEEE 802.1d
standard.
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A message that indicates a LightStream network
event or status. Traps include error messages and reports about port or device
abnormalities. They are usually logged and forwarded to the local console or a
monitoring host as requested.
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The physical and logical connection between
two LightStream switches. Traffic within the LightStream network travels over
trunks.
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A line card configured to communicate with
other LightStream switches. LightStream trunk cards offer V.35, RS-449, X.21,
OC-3c, T3 and E3 interfaces. (LSCs, MSCs, and CLCs can operate as trunk cards.)
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To switch unit. The subsystem on each line
card that appends ATM routing information to outgoing cells and sends the cells
to the switch card.
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Trunk up-down protocol. The TUD protocol
monitors trunks and detects when one goes down or comes up. The switch sends
regular test messages from each trunk port to test trunk line quality. If a
trunk misses a given number of these messages, TUD declares the trunk down.
When a trunk comes back up, TUD recognizes that the trunk is up, declares the
trunk up, and returns it to service.
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User datagram protocol. A member of the IP
familyof protocols, UDP exchanges datagrams without acknowledgements or
guaranteed delivery. UDP is a transport layer interface to the IP layer so that
higher layers can send datagrams that do not guarantee delivery and do not
require the formal establishment of a session with the recipient. UDP is
defined in RFC 768.
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· Traffic within the excess rate (the difference between the insured rate and maximum rate) for the VCC. This traffic can be dropped by the network if congestion occurs.
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· Usage parameter control.
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· User-network interface.
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An ITU-T (formerly CCITT) recommendation
describing a synchronous protocol that conforms to layer 1 (physical) of the
Open Systems Interconnect model. The standard is CCITT Recommendation V.35.
LightStream's low-speed interface modules can provide up to eight V.35 ports
each.
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Virtual circuit. A general term used to
indicate a logical circuit between two end points in a network, for instance a
frame relay virtual circuit.
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(1) Virtual channel connection. A logical
circuit that carries data between two end points in an ATM network. (2) An LED
on each function card indicating that 5-volt power is on.
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· Virtual channel identifier. The VCI is a number used by an ATM device to identify a virtual channel link that makes up a part of the virtual channel connection. Its function is analogous to the DLCI's in frame relay.
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· Virtual channel link. Link (or connection) between two ATM devices (for instance, LightStream switches). A virtual channel connection is made up of one or more virtual channel links.
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A workgroup is a collection of stations on a
LAN that are allowed to communicate with each other. LightStream's workgroup
architecture allows geographically dispersed stations on connected LANs to be
logically grouped, providing easy access within the workgroup while ensuring
privacy between workgroups and limiting the impact of each group's work on the
others. Workgroups are configured on a per-port basis using the LightStream
configurator.
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Virtual LAN internetworking. The set of
features that supports LightStream bridging services by letting LAN stations
communicate as if they were directly connected, without regard for the
structure of the underlying network.
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Virtual path connection. The VPC is a bundle
of virtual channel connections that share one or more contiguous VPLs.
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Virtual path identifier. The VPI is a number
used by an ATM device to identify a virtual path link that makes up a part of a
virtual path connection.
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Virtual path link. Within a virtual path,
multiple unidirectional virtual channel links with the same end points are
regarded as a single entity, a virtual path link. Grouping virtual channel
links in this way reduces the number of connections to be managed, thereby
decreasing network control overhead and cost. A virtual path connection is made
up of one or more virtual path links.
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Wide area network. A data communications
system that serves users over a broad geographic area and often uses
transmission devices provided by common carriers. ATM and time division
multiplexing (TDM) networks are examples of WANs.
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An ITU-T (formerly CCITT) recommendation
defining the interface between a DTE and a DCE, where network access is over
synchronous digital lines. The standard is CCITT Recommendation X.21. The
LightStream X.21 implementation uses the physical (OSI layer 1) X.21 interface
only. LightStream's low-speed interface modules can provide up to eight X.21
ports each. The X.21 protocol is used primarily in Europe and Japan.