HP 316095-B21 - StorageWorks Edge Switch 2/24 User manual

glossary
hp StorageWorks
directors and edge switches
Product Version: FW V05.01.00-24/HAFM SW V07.01.00-09
First Edition (June 2003)
Part Number: AA-RU5JA-TE
This glossary defines terms used in manuals that support HP StorageWorks directors
and edge switches.

© Copyright 2001-2003 Hewlett-Packard Development Company, L.P.
Hewlett-Packard Company makes no warranty of any kind with regard to this material, including, but not limited to,
the implied warranties of merchantability and fitness for a particular purpose. Hewlett-Packard shall not be liable for
errors contained herein or for incidental or consequential damages in connection with the furnishing, performance,
or use of this material.
This document contains proprietary information, which is protected by copyright. No part of this document may be
photocopied, reproduced, or translated into another language without the prior written consent of Hewlett-Packard.
The information contained in this document is subject to change without notice.
Hewlett-Packard Company shall not be liable for technical or editorial errors or omissions contained herein. The
information is provided “as is” without warranty of any kind and is subject to change without notice. The warranties
for Hewlett-Packard Company products are set forth in the express limited warranty statements for such products.
Nothing herein should be construed as constituting an additional warranty.
Printed in the U.S.A.
Directors and Edge Switches Glossary
First Edition (June 2003)
Part Number: AA-RU5JA-TE

3Directors and Edge Switches Glossary
glossary
Glossary
Glossary
This glossary defines terms used in manuals that support the following HP
StorageWorks storage area network (SAN) products:
■Director 2/64
■Director 2/140
■Edge Switch 2/16
■Edge Switch 2/24
■Edge Switch 2/32
The glossary includes terms that relate specifically to the supported products. It
does not include many terms that are generally well-known in the SAN industry.
access control
Method of control (with associated permissions) by which a set of devices can access other
devices across a network. See also persistent binding and zoning.
active configuration
In S/390 mode, the director or switch configuration that is determined by the status of the
connectivity attributes.
active FRU
A redundant field-replaceable unit that is currently operating as the active and not the backup
FRU. See also backup FRU.
active port address matrix
In S/390 mode, an active port address matrix is the port address matrix that is currently active or
operational on an attached director or switch. See also connectivity capability.
active zone set
Single zone set that is active in a multiswitch fabric. It is created when you enable a specified
zone set. This zone set is compiled by checking for undefined zones or aliases.
address name
See port name.

Glossary
4 Directors and Edge Switches Glossary
agent
Software that processes queries on behalf of an application and returns replies.
alarm
Simple network management protocol (SNMP) message notifying an operator of a network or
device problem.
allowed connection
In S/390 mode in a director or switch, the attribute that, when set, establishes dynamic
connectivity capability. See also blocked connection, connectivity attribute, dynamic
connectivity, and unblocked connection.
alias server
Fabric software facility that supports multicast group management.
allowed port connection
In S/390 mode, this attribute establishes dynamic connectivity capability.
area
The second byte of the node port (N_Port) identifier.
arbitrated loop
One of the three connection topologies offered by Fibre Channel protocol. Up to 126 node ports
and one fabric port can communicate without the need for a separate switched fabric.
arbitrated loop physical address
(AL_PA) — A 1-byte value used in the arbitrated loop topology that identifies loop ports
(L_Ports). This value then becomes the last byte of the address identified for each public L_Port
on the loop.
arbitration
Process of choosing one device from a collection of devices that request service simultaneously.
attribute
In S/390 mode, the connection status of the address on a configuration matrix: allowed, blocked,
or prohibited.
audit log
Log summarizing actions (audit trail) made by the user.
authentication
Verification of identity for a person or process.
backbone
Cable on which two or more stations or networks may be attached, typically used to link
computer networks at one site with those at another. Smaller branch networks are sometimes
called ribs.

Glossary
5Directors and Edge Switches Glossary
backplane
The backplane provides 48 VDC power distribution and connections for all logic cards.
backup FRU
When an active field-replaceable unit (FRU) fails, an identical backup FRU takes over operation
automatically (failover) to maintain director and Fibre Channel link operation. See also active
FRU.
BB_Credit
See buffer-to-buffer credit.
beaconing
Use of light-emitting diodes on ports, port cards, field-replaceable units, and directors to aid in
the fault-isolation process. When enabled, active beaconing causes LEDs to flash for selected
components.
BER
See bit error rate.
bezel
A removable panel that covers empty drive bays and port cards.
bidirectional
In Fibre Channel, the capability to simultaneously communicate at maximum speeds
(100 Mbps) in both directions over a link.
bit error rate
(BER) — Ratio of received bits that contain errors to total of all bits transmitted.
blocked connection
In S/390 mode, in a director or switch, the attribute that, when set, removes the communication
capability of a specific port. A blocked address is disabled so that no other address can be
connected to it. A blocked attribute supersedes a dedicated or prohibited attribute on the same
address. See also allowed connection, unblocked connection, connectivity attribute, dynamic
connection, and dynamic connectivity.
blocked port
Devices communicating with the port are prevented from logging into the director or
communicating with other devices attached to the director. A blocked port continuously
transmits the offline sequence.
bridge
Device that connects and passes packets between two network segments that use the same
communications protocol.

Glossary
6 Directors and Edge Switches Glossary
bridge port
(B_Port) — (1) In Fibre Channel protocol, a fabric inter-element port used to connect bridge
devices with E_Ports on a switch. B_Ports provide a subset of E_Port functionality. (2) A term
for a physical interface between the fabric (switch) and a bridge device. The interface is
identical to an expansion port (E_Port), but it does not participate in full expansion port
protocols. As such, it does not assign domain IDs or participate in routing protocol. See also
expansion port, fabric port, generic port, node port, and segmented E_Port.
broadcast
Send a transmission to all node ports (N_Ports) on a fabric. See also broadcast frame and
multicast.
broadcast frame
Data packet, also known as a broadcast packet, whose destination address specifies all
computers on a network. See also broadcast and multicast.
buffer
Storage area for data in transit. Buffers compensate for differences in processing speeds
between devices. See also buffer-to-buffer credit
buffer-to-buffer credit
(BB_Credit) — The maximum number of frames a port can transmit without receiving a receive
ready signal from the receiving device.
CHPID
See channel path identifier.
call-home
Product feature that requires installation of HP Proactive Service software and enables the
HAFM server to automatically transmit system events (failure information) to aN HP customer
support center. The HP support center server accepts calls from the HAFM server, logs reported
events, and can notify one or more support center representatives.
cell
In S/390 mode, in a port address matrix, a cell is the intersection point between a horizontal port
address and a vertical port address. A selected cell is indicated by the cell cursor.
channel
Point-to-point link that transports data from one point to the other.
channel path
A single interface between a central processor and one or more control units along which
signals and data can be sent to perform I/O requests.
channel path identifier
(CHPID) — In a channel subsystem, a value assigned to each installed channel path of the
system that uniquely identifies that path to the system.

Glossary
7Directors and Edge Switches Glossary
channel wrap test
A diagnostic procedure that checks S/390 host-to-director connectivity by returning the output
of the host as input. The test is host-initiated, and transmits Fibre Channel frames to a director
port. A director port enabled for channel wrapping echoes the frame back to the host.
Class 2 Fibre Channel service
Provides a connectionless (not dedicated) service with notification of delivery or nondelivery
between two N_Ports. In-order delivery of frames is not guaranteed.
Class 3 Fibre Channel service
Provides a connectionless (not dedicated) service without notification of delivery or nondelivery
between two N_Ports. Also known as datagram.
Class F Fibre Channel service
Used by switches to communicate across interswitch links (ISLs) to configure, control, and
coordinate a multiswitch fabric.
class of Fibre Channel service
Defines the level of connection dedication, acknowledgment, and other characteristics of a
connection. Class 2, Class 3, and Class F services are supported.
community name (SNMP)
A name that represents a simple network management protocol (SNMP) community that the
agent software recognizes as a valid source for SNMP requests. A product recognizes a
management station as a valid recipient for trap information when the station’s community
names are configured.
community profile
Information that specifies which management objects are available to what management
domain or SNMP community name.
concurrent firmware upgrade
Firmware is upgraded without disrupting switch operation.
concurrent maintenance
Ability to perform maintenance tasks, such as removal or replacement of field-replaceable units
(FRUs), while normal operations continue without interruption. See also nondisruptive
maintenance.
configuration data
Configuration data includes identification data, port configuration data, operating parameters,
SNMP configuration, and zoning configuration. A configuration backup file is required to
restore configuration data if the control processor (CTP) card in a nonredundant director is
removed and replaced.

Glossary
8 Directors and Edge Switches Glossary
connectionless
Nondedicated link. Typically used to describe a link between nodes that allows the switch to
forward Class 2 or Class 3 frames as resources (ports) allow. Contrast this type of link to the
dedicated bandwidth that is required in a Class 1 Fibre Channel Service point-to-point link.
connectivity attribute
In S/390 mode, the characteristic that determines port address status for the director or switch.
See also allowed connection, blocked connection, connectivity capability, connectivity control,
dynamic connection, dynamic connectivity, and unblocked connection.
connectivity capability
(1) The capability that allows attachment of a device to a system without requiring physical
reconfiguration of either the device or the interconnections. (2) The director or switch capability
that allows logical manipulation of link connections to provide physical device attachment. See
also active port address matrix, connectivity attribute, and connectivity control.
connectivity control
In S/390 mode, in a director or switch, the method used to change port address connectivity
attributes and determine the communication capability of the link attached to the port. See also
active port address matrix, connectivity attribute, and connectivity capability.
connector
See optical fiber connector.
control processor card
(CTP card) — Circuit card that contains the director microprocessor. The CTP card also
initializes hardware components of the system after power-on. A 10 Mbps RJ-45 twisted pair
connector is located on the CTP card to connect to an Ethernet LAN and communicate with the
HAFM server or a specific management station.
control unit
A device that controls the reading, writing, or displaying of data at one or more input/output
units.
control unit port
An internal director port on the CTP card that communicates with the attached IBM S/390 or
similar processor channels to report error conditions and link initialization.
CRC
See cyclic redundancy check.
CTP card
See control processor card.
CUP
See control unit port.

Glossary
9Directors and Edge Switches Glossary
cyclic redundancy check
(CRC) — System of error checking performed at both the sending and receiving station using
the value of a particular character generated by a cyclic algorithm. When the values generated at
each station are identical, data integrity is confirmed.
DASD
Direct access storage device, such as a disk drive.
datagram
See Class 3 Fibre Channel service.
data directory
Directory that contains critical information for all managed products (including directors and
switches). Information stored here includes:
■All configuration data
■All log files
■Call-home settings
■Firmware library
■Zoning library
default
Pertaining to an attribute, value, or option that is assumed when none is explicitly specified.
default zone
Contains all attached devices that are not members of a separate zone.
destination identifier
Address identifier that indicates the targeted destination of a data frame.
device
Product (server or storage), connected to a managed director, that is not controlled directly by
the Product Manager application. See also node.
diagnostics
Procedures used by computer users and service personnel to diagnose hardware or software
error conditions.
dialog box
Dialog box is a window containing informational messages or data fields to be modified or
filled in with desired options.
D_ID
See destination identifier.

Glossary
10 Directors and Edge Switches Glossary
director
An intelligent Fibre Channel switching device providing any-to-any port connectivity between
nodes (end devices) on a switched fabric. The director sends data transmissions (data frames)
between nodes in accordance with the address information present in the frame headers of those
transmissions.
DNS name
Domain name system (or domain name service). Host or node name for a device or managed
product that is translated to an internet protocol (IP) address through a domain name server.
domain
A Fibre Channel term describing the most significant byte in the node port (N_Port) identifier
for the Fibre Channel device. It is not used in the Fibre Channel small computer system
interface (FC-SCSI) hardware path ID. It is required to be the same for all SCSI targets logically
connected to a Fibre Channel adapter.
domain ID
Number (1 through 31) that uniquely identifies a switch in a multiswitch fabric. A distinct
domain ID is automatically allocated to each switch in the fabric by the principal switch.
domain name service
See DNS name.
dynamic connection
A connection between two ports, established or removed by the directors and, when active,
displays as one continuous link. See also connectivity attribute, blocked connection,
connectivity capability, dynamic connectivity, and unblocked connection.
dynamic connectivity
The capability that allows connections to be established and removed at any time.
E_D_TOV
See error-detect time-out value.
E_Port
See expansion port.
Embedded Web Server
(EWS) — Web-based interface that allows administrators or operators with a browser-capable
PC and Internet connection to monitor and manage a director. The interface provides a GUI
similar to the Product Manager application and supports director configuration, statistics
monitoring, and basic operation.
error-detect time-out value
(E_D_TOV) — User-specified value that defines the time a director or switch waits for an
expected response before declaring an error condition.

Glossary
11Directors and Edge Switches Glossary
error message
Software message that indicates an error was detected. See also information message and
warning message.
Ethernet
A widely implemented local area network (LAN) protocol that uses a bus or star topology and
serves as the basis for the IEEE 802.3 standard, which specifies the physical and software
layers. Baseband LAN allows multiple station access to the transmission medium at will
without prior coordination and which avoids or resolves contention.
Ethernet hub
A customer-supplied device used to LAN-connect the HAFM server and the directors it
manages.
event code
A three-digit numeric code that displays in the event log and identifies a specific event that
occurred. This code provides information on system failures, such as hardware failures; failure
locations; or general information on normal system events.
event log
Record of significant events that have occurred at the director or switch or through the HAFM
Management Services application, such as FRU failures, degraded operation, and port problems.
expansion port
(E_Port) — Physical interface on a Fibre Channel switch within a fabric that attaches to an
expansion port (E_Port) on another Fibre Channel switch to form a multiswitch fabric. See also
segmented E_Port.
explicit fabric login
Data field size, supported by an F_Port, that is agreed upon during fabric login.
fabric
Fibre Channel entity that interconnects node ports (N_Ports) and is capable of routing
(switching) Fibre Channel frames using the destination ID information in the Fibre Channel
frame header accompanying the frames.
fabric address notification
(FAN) — A message that informs all NL_Ports of the address of the FL_Port. Allows LIP
processing to not be disruptive to FC traffic on devices that support FAN. See also loop
initialization primitive.
fabric element
An active switch, director, or node in a Fibre Channel switched fabric.

Glossary
12 Directors and Edge Switches Glossary
fabric login
The process by which node ports (N_Ports) establish their operating parameters. During fabric
login, the presence or absence of a fabric is determined and paths to other N_Ports are mapped.
Specific operating characteristics for each port, such as buffer-to-buffer credit (BB_Credit) and
data frame size, are also established.
fabric port
(F_Port) — Physical interface within the fabric that connects to an N_Port through a
point-to-point full duplex connection.
fabric services
The services that implement the various Fibre Channel protocol services, which are described in
the standards. These services include the fabric controller (login server), name server, and
management server.
failover
Automatic and nondisruptive transition of functions from an active FRU that has failed to a
backup FRU.
FAN
See fabric address notification.
FCC-IOC
See Fibre Channel input/output controller.
feature key
A unique key that allows additional product features to be enabled. This key is entered into the
Configure Feature Key dialog box in the Product Manager application to activate optional
hardware and software features. Upon purchasing a new feature, customers will receive the
associated feature key.
fiber
Physical media types supported by the Fibre Channel specification, such as optical fiber, copper
twisted pair, and coaxial cable.
Fibre Channel
Integrated set of standards recognized by the American national Standards Institute (ANSI),
which defines specific protocols for flexible information transfer. Logically, a point-to-point
serial data channel, structured for high performance.
Fibre Channel fabric element
Any device linked to a fabric. Information about these devices is recorded in a management
information base (MIB), which can be accessed by fabric management software.
Fibre Channel input/output controller
(FCC-IOC) — A device that controls the embedded Fibre Channel port and configures the
port’s ASICs.

Glossary
13Directors and Edge Switches Glossary
fiber optics
Branch of optical technology concerned with the transmission of light pulses through fibers
made of transparent materials such as glass, fused silica, and plastic.
fiber port module card
A 1 gigabit per second module that contains four generic ports (G_Ports). Each fiber module
card provides connections through duplex small form factor pluggable (SFP) fiber optic
transceivers.
FICON
An IBM set of products and services introduced in 1999 that is based on the Fibre Channel
Standard. FICON technology uses fiber optic cables as the data transmission medium and
significantly improves I/O performance (including 1 Gbps bidirectional data transfer).
FICON Management Server
An optional feature that can be enabled on the director or switch through the Product Manager
application. When enabled, host control and management of the director or switch is provided
through an S/390 Parallel Enterprise or zSeries server attached to a director or switch port.
field-replaceable unit
(FRU) — Assembly removed and replaced in its entirety when any one of its components fails.
See also active FRU.
firmware
Embedded program code that resides and executes on directors, switches, and hubs.
FPM card
See fiber port module card.
F_Port
See fabric port.
FRU
See field-replaceable unit.
gateway
A multi-homed host used to route network traffic from one network to another, and to pass
network traffic from one protocol to another.
gateway address
A unique string of numbers (in the format xxx.xx.xxx.xxx) that identifies a gateway on the
network.
generic port
(G_Port) — Physical interface on a director that can function either as a fabric port (F_Port) or
an expansion port (E_Port) depending on the port type to which it connects.

Glossary
14 Directors and Edge Switches Glossary
G_Port
See generic port.
HAFM application
See High Availability Fabric Manager application.
HAFM server
See High Availability Fabric Manager server.
hardware log
Record of FRU insertions and removals for a director or switch.
hardware management console
The console runs the Hardware Management Console application (HWMCA), and is the
operations and management PC platform for S/390 and zSeries servers.
HBA
See host bus adapter.
heterogeneous fabric
A fabric containing open-fabric-compliant products from various vendors (HP and non-HP).
See also homogeneous fabric.
high availability
A performance feature characterized by hardware component redundancy and hot-swappability
(enabling non-disruptive maintenance). High-availability systems maximize system uptime
while providing superior reliability, availability, and serviceability.
High Availability Fabric Manager application
(HAFM) — Application that implements the management user interface for HP Fibre Channel
switching products and as a launching point for the Product Manager application. The
application runs locally on the HAFM server or on a remote workstation.
High Availability Fabric Manager server
Notebook computer shipped with a director to run the HAFM and Product Manager
applications.
hop
Data transfer from one fabric node to another node.
homogeneous fabric
A fabric consisting of only HP products. See also heterogeneous fabric.
hop count
The number of hops a unit of information traverses in a fabric.
host bus adapter
(HBA) — Logic card that provides a link between the server and storage subsystem and
integrates the operating systems and I/O protocols to ensure interoperability.

Glossary
15Directors and Edge Switches Glossary
hot-swapping
Removing and replacing a device’s components while the device continues to operate normally.
hub
In Fibre Channel protocol, a device that connects nodes into a logical loop by using a physical
star topology. In an Ethernet system, a device used to connect the HAFM server and the
directors it manages.
IML
See initial machine load.
inband management
Management of the director or switch through a Fibre Channel connection to a port card. See
also out-of-band management.
information message
Software message that indicates to a user that a function is performing normally or has
completed normally. See also error message and warning message.
initial machine load
(IML) — Hardware reset for all installed CTP cards on the director. It does not affect other
hardware. It is initiated by pushing the white button on a director’s CTP card.
initial program load
(IPL) — Process of initializing the device and causing the operating system to start. Initiated
through a menu in the Product Manager, this option performs a hardware reset on the active
CTP only.
initial program load configuration
(IPL configuration) — In S/390 mode, information containing default configurations stored in a
director or switch’s nonvolatile memory. The director or switch loads the file for operation when
powered on.
input/output configuration
The collection of channel paths, control units, and I/O devices that attaches to the S/390 or
zSeries processor.
input/output configuration program
A program that defines all available I/O devices and channel paths to an IBM S/390 or zSeries
processor system. Replaced by the Hardware Configuration Definition Program starting with
MVS/ESA Version 4.0.
interface
Hardware, software, or both hardware and software that link systems, programs, or devices.
internet protocol address
(IP address) — Unique string of numbers (in the format xxx.xxx.xxx.xxx) that identifies a
device on a network.

Glossary
16 Directors and Edge Switches Glossary
interoperability
Ability to communicate, execute programs, or transfer data between various functional units
over a network.
interoperability mode
(interop mode) — An operating mode, set through management software, that allows products
to operate in homogeneous or heterogeneous fabrics.
interswitch link
(ISL) — Physical expansion port (E_Port) connection between two directors in a fabric.
IOCDS
A data set that contains an I/O configuration definition built by the IOCP.
IOCP
See input/output configuration program.
IP address
See internet protocol address.
IPL
See initial program load.
ISL
See interswitch link.
jumper cable
Optical cable that provides physical attachment between two devices or between a device and a
distribution panel. See also trunk cable.
latency
The amount of time it takes for data transmission to pass through a switching device. When
used in reference to a Fibre Channel switching device, latency refers to the amount of time
elapsed between receipt of a data transmission at a switch’s incoming F_Port (from the
originating node port) to retransmission of that data at the switch’s outgoing F_Port (to the
destination N_Port).
LIN
See link incident.
link
Physical connection between two devices on a switched fabric.
link incident
(LIN) — Interruption to a Fibre Channel link due to loss of light or other causes.

Glossary
17Directors and Edge Switches Glossary
link incident log
Log, displayed through the Product Manager application, that provides a history of Fibre
Channel link incidents (with associated port numbers) for an individual director or switch. See
also audit log, event log, hardware log, and threshold alert log.
load balancing
Ability to evenly distribute traffic over multiple interswitch links within a fabric. Load
balancing on HP directors takes place automatically.
logical port address
The port numbering system for a director with the FICON Management Server active.
logical unit number
(LUN) — In Fibre Channel addressing, a logical unit number is a number assigned to a storage
device, which, in combination with the storage device’s node port’s World Wide Name,
represents a unique identifier for a logical device on a storage area network.
loop initialization primitive
(LIP) — In an arbitrated loop device, a process by which devices connected to hub ports
(H_Ports) on the arbitrated loop device notify other devices and the switch of their presence in
the loop by sending LIP sequences and subsequent frames through the loop. This process allows
linked arbitrated loop devices to perform fabric loop port (FL_Port) arbitration as they link
through hub ports.
loopback plug
In a fiber optic environment, a type of duplex connector used to wrap the optical output signal of
a device directly to the optical input.
loopback test
Test that checks attachment or control unit circuitry, without checking the mechanism itself, by
returning the output of the mechanism as input.
LUN
See logical unit number.
MAC address
See Media Access Control address.
maintenance analysis procedure
(MAP) — A set of procedures that guide maintenance personnel through step-by-step
instructions for hardware fault isolation, repair, and verification.
maintenance port
Connector on the director where a PC running an ASCII terminal emulator can be attached or a
dial-up connection can be made for specialized maintenance support.

Glossary
18 Directors and Edge Switches Glossary
managed product
Hardware product that can be managed with the HAFM application. For example, the
Director 2/64 and the Edge Switch 2/32 are managed products. See also device.
Management Information Base
(MIB) — Related set of software objects (variables) containing information about a managed
device and accessed via SNMP from a network management station.
Management Services application
Software application that provides back-end product-independent services to the HAFM
application. Management Services runs only on the HAFM server and cannot be downloaded to
remote workstations.
management session
A management session exists when a user logs on to the HAFM server. The HAFM application
can support multiple concurrent management sessions. The user must specify the network
address of the HAFM server at logon time.
MAP
See maintenance analysis procedure.
Media Access Control address
(MAC) — Hardware address of a node (device) connected to a network.
MIB
See Management Information Base.
multicast
Delivery of a single transmission to multiple destination N_Ports. Can be one-to-many or
many-to-many. All members of the group are identified by one IP address. See also broadcast.
multiswitch fabric
Fibre Channel fabric created by linking more than one director or switching device within a
fabric.
name server
Program that translates names from one form into another. For example, the domain name
server (DNS) translates domain names into IP addresses.
name server zoning
N_Port access management that allows N_Ports to communicate if and only if they belong to a
common name server zone.

Glossary
19Directors and Edge Switches Glossary
network address
Name or address that identifies a managed product on a transmission control protocol/internet
protocol (TCP/IP) network. The network address can be either an IP address in dotted-decimal
notation (containing four three-digit octets in the format xxx.xxx.xxx.xxx), or a domain name
(as administered on a customer network).
never principal
The setting that prevents the product from becoming the principal switch for a fabric.
nickname
Alternate name assigned to a World Wide Name for a node or director in the fabric.
node
In Fibre Channel terminology, node refers to an end device (server or storage device) that is or
can be connected to a switched fabric.
node port
(N_Port) — Physical interface within an end device that can connect to a fabric port (F_Port) on
a switched fabric or directly to another N_Port (in point-to-point communications).
node port identifier
(N_Port ID) — In Fibre Channel protocol, a unique address identifier by which an N_Port is
uniquely known. It consists of a domain (most significant byte), an area, and a port, each 1 byte
long. The N_Port ID is used in the source identifier (S_ID) and destination identifier (D_ID)
fields of a Fibre Channel frame.
nondisruptive maintenance
Ability to service FRUs (including maintenance, installation, removal and replacement) while
normal operations continue without interruption. See also concurrent maintenance.
N_Port
See node port.
offline sequence
(OLS) — Sequence sent by the transmitting port to indicate that it is attempting to initialize a
link and has detected a problem in doing so.
offline state
When the switch or director is in the offline state, all the installed ports are offline. The ports
transmit an offline sequence (OLS) and they cannot accept a login connection from an attached
device. See also online state.
OLS
See offline sequence.

Glossary
20 Directors and Edge Switches Glossary
online state
When the switch or director is in the online state, all of the unblocked ports are allowed to log in
to the fabric and begin communicating. Devices can connect to the switch or director if the port
is not blocked and can communicate with another attached device if both devices are in the
same zone, or if the default zone is enabled. See also offline state.
Open Systems Management Server
An optional feature that can be enabled on the director or switch through the Product Manager
application. When enabled, host control and management of the director or switch are provided
through an open systems interconnection (OSI) device attached to a director or switch port.
Open Trunking
Open Trunking is a licensed optional feature that enables load balancing of traffic flows. Open
Trunking monitors the average speed of data traffic through a flow. In the event of traffic
congestion, or if traffic on an ISL is disproportionate, a traffic flow is rerouted to a less
congested ISL. See also interswitch link.
Operating System/390
(OS/390) — An integrated, open-enterprise server operating system developed by IBM that
incorporates a leading-edge and open communications server, distributed data and file services,
parallel Sysplex support, object-oriented programming, distributed computing environment, and
open application interfaces.
optical cable
Fiber, multiple fibers, or a fiber bundle in a structure built to meet optical, mechanical, and
environmental specifications. See also jumper cable, optical cable assembly, and trunk cable.
optical cable assembly
Optical cable that is connector-terminated. See also jumper cable and optical cable.
optical fiber connector
Hardware component that transfers optical power between two optical fibers or bundles and is
designed to be repeatedly connected and disconnected.
out-of-band management
Transmission of management information using frequencies or channels (Ethernet) other than
those routinely used for information transfer (Fibre Channel). See also inband management
packet
Logical unit of information (usually in the form of a data frame) transmitted on a network. It
contains a header (with all relevant addressing and timing information), the actual data, and a
trailer (which contains the error checking function, usually in the form of a cyclic redundancy
check).