IBM 2109 Model M12 User Manual page 82

IOD. See in-order delivery.
IP. See internet protocol.
IPA. Initial process associator.
ISL. See inter-switch link.
ISL Trunking. A feature that enables distribution of
traffic over the combined bandwidth of up to four
inter-switch links (ISLs) (between adjacent switches),
while preserving in-order delivery. A set of trunked ISLs
is called a trunking group; each port employed in a
trunking group is called a trunking port. See also master
port.
isolated E_port. An expansion port (E_port) that is
online but not operational between switches due to
overlapping domain ID or nonidentical parameters such
as error delay timeout values (E_D_TOVs). See also
expansion port.
IU. See information unit.
K28.5. A special 10-bit character used to indicate the
beginning of a transmission word that performs fibre
channel control and signaling functions. The first seven
bits of the character are the comma pattern. See also
comma.
kernel flash. Flash memory that stores the bootable
kernel code and is visible within the memory space of
the processor. Data is stored as raw bits.
key pair. In public key cryptography, a pair of keys
consisting of a public and private key of an entity. The
public key can be publicized, but the private key must
be kept secret.
LAN. See local area network.
latency. The period of time required to transmit a
frame, from the time it is sent until it arrives.
LED. See light-emitting diode.
light-emitting diode (LED). A semiconductor chip that
gives off visible or infrared light when activated.
link. As applies to fibre channel, a physical connection
between two ports, consisting of both transmit and
receive fibers. See also circuit.
link services. A protocol for link-related services.
LIP. See loop initialization primitive.
LM_TOV. See loop master timeout value.
local area network (LAN). A computer network
located on a user's premises within a limited
geographical area. (T)
62
IBM TotalStorage SAN Switch: 2109 Model M12 User's Guide
logical unit number (LUN). An identifier used on a
small computer systems interface (SCSI) bus to
distinguish among up to eight devices (logical units) with
the same SCSI ID.
long wavelength (LWL). A type of fiber optic cabling
that is based on 1300 mm lasers and supports link
speeds of 1.0625 Gbps. Can also refer to the type of
GBIC or SFP. See also short wavelength.
loop. A configuration of devices that are connected to
the fabric by way of a fabric loop port (FL_port)
interface card.
loop circuit. A temporary bidirectional communication
path established between loop ports (L_ports).
loop failure. Loss of signal within a loop for any
period of time, or loss of synchronization for longer than
the timeout value.
loop_ID. A hexadecimal value representing one of the
127 possible arbitrated loop physical address (AL_PA)
values in an arbitrated loop.
loop initialization. The logical procedure used by a
loop port (L_port) to discover its environment. Can be
used to assign arbitrated loop physical address (AL_PA)
addresses, detect loop failure, or reset a node.
loop initialization primitive (LIP). The signal used to
begin initialization in a loop. Indicates either loop failure
or resetting of a node.
looplet. A set of devices connected in a loop to a port
that is a member of another loop.
loop master timeout value (LM_TOV). The minimum
time that the loop master waits for a loop initialization
sequence to return.
loop mode. One of the modes for a loop port (L_port).
An L_port is in loop mode when it is in an arbitrated
loop and is using loop protocol. An L_port in loop mode
can also be in participating mode or nonparticipating
mode. See also loop port, fabric mode, participating
mode, and nonparticipating mode.
loop port (L_port). A node port (NL_port) or fabric
port (FL_port) that has arbitrated loop capabilities. An
L_port can be either in fabric mode or loop mode. See
also fabric mode , loop mode, nonparticipating mode,
and participating mode.
loop port state machine (LPSM). The logical entity
that performs arbitrated loop protocols and defines the
behavior of loop ports (L_ports) when they require
access to an arbitrated loop.
L_port. See loop port.
LPSM. See loop port state machine.
LSR. Link state record.