A
ACC
Accept Link Service reply. Accept is the normal reply to an Extended Link Service request (such as FLOGI) and indicates that the request has been completed.
ACK
Acknowledgement Frame. An ACK is used for end-to-end flow control. An ACK is sent to verify receipt of one or more frames in Class 1 and Class 2 Services.
Address Identifier
A 3-byte value typically assigned by the Fabric used to address an N_Port. Used in frames in the S_ID (source identifier) and D_ID (destination identifier) fields.
AL_PA
Arbitrated Loop Physical Address. A 1-byte value used in the Arbitrated Loop topology used to identify L_Ports. This value will then also become the last byte of the address identifier for each public L_Port on the loop
AL_TIME
Arbitrated Loop Timeout value. Twice the amount of time it would take for a Transmission Word to propagate around a worst-case Loop, i.e. a Loop with 134 L_Ports and 10 km links between each L_Port, with a 6 Transmission Word delay through each L_Port. This value is set at 15 ms.
Arbitrated Loop
One of the three Fibre Channel topologies. Up to 126 NL_Ports and 1 FL_Port are configured in a unidirectional loop. Ports arbitrate for access to the Loop based on their AL_PA. Ports with lower AL_PA's have higher priority than those with higher AL_PA's.
ARB
Arbitrate Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is transmitted as the Fill Word by an L_Port to indicate that the L_Port is arbitrating to access to the Loop.
B
BB_Credit
Buffer-to-buffer credit value. Used for buffer-to-buffer flow control, this determines the number of frame buffers available in the port it is attached to, i.e., the maximum number of frames it may transmit without receiving an R_RDY.
C
Class 1 Service
A method of communicating between N_Ports in which a dedicated connection is established between them. The ports are guaranteed the full bandwidth of the connection and frames from other N_Ports may be blocked while the connection exists. In-order delivery of frames is guaranteed. Uses end-to-end flow control only.
Class 2 Service
A method of communicating between N_Ports in which no connection is established. Frames are acknowledged by the receiver. Frames are routed through the Fabric, and each frame may take a different route. In-order delivery of frames is not guaranteed. Uses both buffer-to-buffer flow and end-to-end flow control.
Class 3 Service
A method of communicating between N_Ports similar to Class 2 service, except there is no acknowledgment of received frames. Frames are routed through the Fabric as in Class 2, and in-order delivery is not guaranteed. Uses only buffer-to-buffer flow control.
CLS
Close Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is Primitive Signal is sent by an L_Port which is currently communicating on the Loop (i.e., it has won access to the loop or was opened by another L_Port which had won access to the Loop) to close communication with the other L_Port.
D
D_ID
Destination identifier. A 3-byte field in the frame header used to indicate the address identifier of the N_Port the frame is to be delivered to.
Disparity
The difference between the number of 1's and 0's in a Transmission Character. A Transmission Character with more 1's than 0's is said to have positive running disparity. A Transmission Character with more 0's than 1's is said to have negative running disparity. A Transmission Character with an equal number of 1's and 0's is said to have neutral disparity.
E
E_D_TOV
Error Detect Timeout value. A timer used to represent the longest possible time for a frame to make a roundtrip through the Fabric. This value is negotiated at N_Port Login and will typically be on the order of a few seconds. E_D_TOV is used to decide when some particular error recovery action must be taken.
EE_Credit
End-to-end credit value. Used for end-to-end flow control, determines the maximum number of frames that may remain unacknowledged.
EOF
End of Frame delimiter. This Ordered Set is always the last Transmission Word of a Frame. It is used to indicate that a Frame has ended and indicates whether the Frame is valid or invalid.
Exchange
The highest level Fibre Channel mechanism used for communication between N_Ports. Exchanges are composed of one or more related sequences. Exchanges may be bidirectional or unidirectional.
F
Fabric
One of the three Fibre Channel topologies. In the Fabric topology, N_Ports are connected to F_Ports on a switch. Depending on vendor support, fabric switches may be interconnected to support up to 16 million+ N_Ports on a single network.
F_BSY
Fabric Port Busy Frame. This Frame is issued by the Fabric to indicate that a particular cannot be delivered because the Fabric or the destination N_Port is too busy.
FC-AL
Fibre Channel Arbitrated Loop. Refers to the ANSI FC-AL document which specifies operation of the Arbitrated Loop topology.
FC-PH
Fibre Channel Physical and Signaling Interface. Refers to the ANSI FC-PH document which specifies the FC-0, FC-1, and FC-2 layers of the Fibre Channel protocol. FC-0 Fibre Channel layer 0. Specifies the physical signalling used in Fibre Channel, as well as cable plants, media types, and transmission speeds.
FC-1
Fibre Channel layer 1. Specifies the IBM patented 8B/10B data encoding used in Fibre Channel.
FC-2
Fibre Channel layer 2. Specifies the frame format, Sequence/Exchange management, and Ordered Set usage in Fibre Channel.
FC-3
Fibre Channel layer 3. Specifies services provided for multiple N_Ports in a single node.
FC-4
Fibre Channel layer 4. Specifies mapping of Upper Level Protocols such as SCSI and IP onto the Fibre Channel Protocol.
Fill Word
The Primitive Signal is used by L_Ports to be transmitted in between Frames. This may be Idle or ARBx, depending on which, if any, L_Ports are Arbitrating for Loop access, and will not necessarily be the same for all L_Ports on the Loop at any given time.
FL_Port
Fabric-Loop port. An F_Port which is capable of supporting an attached Arbitrated Loop. An FL_Port on a Loop will have the AL_PA hex'00', giving the Fabric highest priority access to the Loop. An FL_Port is the gateway to the Fabric for NL_Ports on a Loop.
F/NL_Port
An NL_Port which is capable of providing certain Fabric services to other NL_Ports on a Loop in the absence of a Fabric. This NL_Port will respond to requests to open communication with AL_PA hex'00', even though it may actually have another value for its AL_PA.
F_Port
Fabric port. A port on a fabric switch to which N_Ports may be directly connected. An F_Port is uses the address identifier hex'FFFFFE'.
Frame
The basic unit of communication between two N_Ports. Frames are composed of a starting delimiter (SOF), a header, the payload, the Cyclic Redundancy Check (CRC), and an ending delimiter (EOF). The SOF and EOF contain the Special Character and are used to indicate where the frame begins and ends. The 24-byte header contains information about the frame, including the S_ID, D_ID, routing information, the type of data contained in the payload, and sequence/exchange management information. The payload contains the actual data to be transmitted, and may be 0-2112 bytes in length. The CRC is a 4-byte field used for detecting bit errors in the received frame.
F_RJT
Fabric Port Reject Frame. This Frame is issued by the Fabric to indicate that delivery of a particular frame is being denied. Some reasons for issuing an F_RJT include: Class not supported; invalid header field(s); and N_Port unavailable.
G H I
Idle
An Ordered Set transmitted continuously over a link when no data are being transmitted. Idle is transmitted to maintain an active link over a fibre and lets the receiver and transmitter maintain bit, byte, and word synchronization.
Intermix
A service in which Class 2 and Class 3 frames may be delivered to an N_Port which has a Class 1 dedicated connection open. The Class 2 and 3 frames are delivered during times which no Class 1 frames are being delivered on the connection.
J K L
Link Service
Link Services are facilities used between an N_Port and a Fabric or between two N_Ports and are used to for such purposes as Login, Sequence and Exchange management, and maintaining connections.
LIP
Loop Initialization Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to (re)initialize the Loop.
LIFA
Loop Initialization Fabric Assigned Frame. This is the first Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which have been assigned their AL_PA by the Fabric will select their AL_PA's in this frame as it makes its way around the Loop.
LIHA
Loop Initialization Hard Assigned Frame. This is the third Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which have been programmed to select a particular AL_PA (if available) by the manufacturer will select their AL_PA's in this frame as it makes its way around the Loop.
LILP
Loop Initialization Loop Position Frame. This is the second Frame transmitted in the Loop initialization process after all L_Ports have selected an AL_PA (after LISA has been around the loop). This Frame is transmitted around the Loop so that all L_Ports may know the relative position of all other L_Ports around the Loop. Support for this Frame by an L_Port is optional.
LIPA
Loop Initialization Previously Assigned Frame. This is the second Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which had an AL_PA prior to the Loop initialization will select their AL_PA's in this frame as it makes its way around the Loop.
LIRP
Loop Initialization Report Position Frame. This is the first Frame transmitted in the Loop initialization process after all L_Ports have selected an AL_PA (after LISA has been around the loop). This Frame is transmitted around the Loop so that all L_Ports report their relative physical position on the loop. Support for this Frame by an L_Port is optional.
LISA
Loop Initialization Soft Assigned Frame. This is the fourth Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which did not select an AL_PA in any of the previous Loop Initialization Frames (LIFA, LIPA, or LIHA) will select their AL_PA's in this frame as it makes its way around the Loop.
LISM
Loop Initialization Select Master Frame. This Frame applies only to the Arbitrated Loop topology. It is the first frame transmitted in the initialization process in which L_Ports select an AL_PA. It is used to select a temporary Loop master, or the L_Port that will subsequently initiate transmission of the remaining initialization frames (LIFA, LIPA, LIHA, LISA, LIRP, and LILP).
LPB
Loop Port Bypass Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to bypass the L_Port it is directed to. For example, if Port A suspects that Port B is malfunctioning, Port A can send an LPB to Port B so that Port B will only retransmit everything it receives, and will not be active on the Loop.
LPE
Loop Port Enable Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to enable an L_Port which has been bypassed with the LPB Primitive Sequence.
L_Port
Loop port. Generic term for an NL_Port or FL_Port, i.e., any Fibre Channel port which supports the Arbitrated Loop topology.
LPSM
Loop Port State Machine. This is a state machine maintained by an L_Port to track its behavior through different phases of Loop operation, i.e., how it behaves when it is arbitrating for Loop access, how it behaves when it has control of the Loop, etc.
LR
Link Reset Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. The expected response to a port sending LR is the LRR Primitive Sequence.
LRR
Link Reset Response Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent in response to the LR Primitive Sequence. The expected response to a port sending LRR is Idle.
M
MRK
Mark Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is transmitted by an L_Port for synchronization purposes and its use is vendor specific.
N
NL_Port
Node-Loop port. An N_Port which can operate on the Arbitrated Loop topology.
Nonparticipating Mode
An L_Port will enter the nonparticipating mode if there are more than 127 devices on a Loop, and it thus cannot acquire an AL_PA. An L_Port may also voluntarily enter the nonparticipating mode if it is still physically connected to the Loop, but wishes not to participate. An L_Port in the nonparticipating mode is not capable of generating Transmission Words on the Loop and may only retransmit words received on its inbound fibre.
NOS
Not Operational Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent to indicate that that transmitting port has detected a link failure or is offline. The expected response to a port sending NOS is the OLS Primitive Sequence.
N_Port
Node port. A port on a computer, disk drive, etc. through which the device does its Fibre Channel communication.
N_Port Name
An 8-byte manufacturer-assigned value which uniquely identifies the N_Port throughout the world.
O
OLS
Offline Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent to indicate that the transmitting port is attempting to initialize the link, has recognized the NOS Primitive Sequence, or is going offline. The expected response to a port sending OLS is the LR Primitive Sequence.
OPN
Open Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. The OPN Primitive Signal is sent by an L_Port that has won the arbitration process to open communication with with one or more other ports on the Loop.
Ordered Set
A 4-byte Transmission Word which has the Special Character as its first Transmission Character. An Ordered Set may be a Frame Delimiter, a Primitive Signal, or a Primitive Sequence. Ordered Sets are used to distinguish Fibre Channel control information from data.
Originator
The N_Port which originated an Exchange.
OX_ID
Originator Exchange Identifier. A 2-byte field in the frame header used by the originator of an Exchange to identify frames as being part of a particular Exchange.
P
Participating Mode
The normal operating mode for an L_Port on a Loop. An L_Port in this mode has acquired an AL_PA and is capable of communicating on the Loop.
Primitive Sequence
An Ordered Set transmitted repeatedly and used to establish and maintain a link. LR, LRR, NOS, and OLS are Primitive Sequences used to establish an active link in a connection between two N_Ports or an N_Port and an F_Port. LIP, LPB, and LPE are Primitive Sequences used in the Arbitrated Loop topology for initializing the Loop and enabling or disabling an L_Port.
Primitive Signal
An Ordered Set used to indicate an event. Idle and R_RDY are used in all three topologies. ARB, OPN, CLS, and MRK are used only in the Arbitrated Loop topology.
Private Loop
An Arbitrated Loop which stands on its own, i.e., it is not connected to a Fabric.
Private NL_Port
An NL_Port which only communicates with other ports on the loop, not with the Fabric. Note that a Private NL_Port may exist on either a Private Loop or a Public Loop.
Public Loop
An Arbitrated Loop which is connected to a Fabric.
Public NL_Port
An NL_Port which may communicate with other ports on the Loop as well as through an FL_Port to other N_Ports connected to the Fabric.
Q R
Responder
The N_Port to with which an Exchange originator wishes to communicate.
RX_ID
Responder Exchange Identifier. A 2-byte field in the frame header used by the responder of the Exchange to identify frames as being part of a particular Exchange.
S
Sequence
A group of related frames transmitted unidirectionally from one N_Port to another.
SEQ_ID
Sequence Identifier. A 1-byte field in the frame header used to identify which Sequence of an Exchange a particular frame belongs to.
Sequence Initiator
The N_Port which began a new Sequence and transmits frames to another N_Port.
Sequence Recipient
The N_Port to which a particular Sequence of data frames is directed.
S_ID
Source Identifier. A 3-byte field in the frame header used to indicate the address identifier of the N_Port the frame was sent from.
SOF
Start of Frame delimiter. This Ordered Set is always the first Transmission Word of a Frame. It is used to indicate that a Frame will immediately follow and indicates which class of service the Frame will use.
Special Character
A special 10-bit Transmission Character which does mot have a corresponding 8-bit value, but is still considered valid. The Special Character is used to indicate that a particular Transmission Word is an Ordered Set. The Special Character is the only Transmission Character to have 5 1's or 0's in a row. The Special Character is also referred to as K28.5 when using K/D format.
T
Transmission Character
A (valid or invalid) 10-bit character transmitted serially over the fibre. Valid Transmission Characters are determined by the 8B/10B encoding specification.
Transmission Word
A string of four consecutive Transmission Characters.
U
ULP
Upper Level Protocol. The protocol which runs on top of Fibre Channel through the FC-4 layer. Typical ULPs running over Fibre Channel are Small Computer System Interface (SCSI), Internet Protocol (IP), High Performance Parallel Interface (HIPPI), and Intelligent Peripheral Interface (IPI).
ACC
Accept Link Service reply. Accept is the normal reply to an Extended Link Service request (such as FLOGI) and indicates that the request has been completed.
ACK
Acknowledgement Frame. An ACK is used for end-to-end flow control. An ACK is sent to verify receipt of one or more frames in Class 1 and Class 2 Services.
Address Identifier
A 3-byte value typically assigned by the Fabric used to address an N_Port. Used in frames in the S_ID (source identifier) and D_ID (destination identifier) fields.
AL_PA
Arbitrated Loop Physical Address. A 1-byte value used in the Arbitrated Loop topology used to identify L_Ports. This value will then also become the last byte of the address identifier for each public L_Port on the loop
AL_TIME
Arbitrated Loop Timeout value. Twice the amount of time it would take for a Transmission Word to propagate around a worst-case Loop, i.e. a Loop with 134 L_Ports and 10 km links between each L_Port, with a 6 Transmission Word delay through each L_Port. This value is set at 15 ms.
Arbitrated Loop
One of the three Fibre Channel topologies. Up to 126 NL_Ports and 1 FL_Port are configured in a unidirectional loop. Ports arbitrate for access to the Loop based on their AL_PA. Ports with lower AL_PA's have higher priority than those with higher AL_PA's.
ARB
Arbitrate Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is transmitted as the Fill Word by an L_Port to indicate that the L_Port is arbitrating to access to the Loop.
B
BB_Credit
Buffer-to-buffer credit value. Used for buffer-to-buffer flow control, this determines the number of frame buffers available in the port it is attached to, i.e., the maximum number of frames it may transmit without receiving an R_RDY.
C
Class 1 Service
A method of communicating between N_Ports in which a dedicated connection is established between them. The ports are guaranteed the full bandwidth of the connection and frames from other N_Ports may be blocked while the connection exists. In-order delivery of frames is guaranteed. Uses end-to-end flow control only.
Class 2 Service
A method of communicating between N_Ports in which no connection is established. Frames are acknowledged by the receiver. Frames are routed through the Fabric, and each frame may take a different route. In-order delivery of frames is not guaranteed. Uses both buffer-to-buffer flow and end-to-end flow control.
Class 3 Service
A method of communicating between N_Ports similar to Class 2 service, except there is no acknowledgment of received frames. Frames are routed through the Fabric as in Class 2, and in-order delivery is not guaranteed. Uses only buffer-to-buffer flow control.
CLS
Close Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is Primitive Signal is sent by an L_Port which is currently communicating on the Loop (i.e., it has won access to the loop or was opened by another L_Port which had won access to the Loop) to close communication with the other L_Port.
D
D_ID
Destination identifier. A 3-byte field in the frame header used to indicate the address identifier of the N_Port the frame is to be delivered to.
Disparity
The difference between the number of 1's and 0's in a Transmission Character. A Transmission Character with more 1's than 0's is said to have positive running disparity. A Transmission Character with more 0's than 1's is said to have negative running disparity. A Transmission Character with an equal number of 1's and 0's is said to have neutral disparity.
E
E_D_TOV
Error Detect Timeout value. A timer used to represent the longest possible time for a frame to make a roundtrip through the Fabric. This value is negotiated at N_Port Login and will typically be on the order of a few seconds. E_D_TOV is used to decide when some particular error recovery action must be taken.
EE_Credit
End-to-end credit value. Used for end-to-end flow control, determines the maximum number of frames that may remain unacknowledged.
EOF
End of Frame delimiter. This Ordered Set is always the last Transmission Word of a Frame. It is used to indicate that a Frame has ended and indicates whether the Frame is valid or invalid.
Exchange
The highest level Fibre Channel mechanism used for communication between N_Ports. Exchanges are composed of one or more related sequences. Exchanges may be bidirectional or unidirectional.
F
Fabric
One of the three Fibre Channel topologies. In the Fabric topology, N_Ports are connected to F_Ports on a switch. Depending on vendor support, fabric switches may be interconnected to support up to 16 million+ N_Ports on a single network.
F_BSY
Fabric Port Busy Frame. This Frame is issued by the Fabric to indicate that a particular cannot be delivered because the Fabric or the destination N_Port is too busy.
FC-AL
Fibre Channel Arbitrated Loop. Refers to the ANSI FC-AL document which specifies operation of the Arbitrated Loop topology.
FC-PH
Fibre Channel Physical and Signaling Interface. Refers to the ANSI FC-PH document which specifies the FC-0, FC-1, and FC-2 layers of the Fibre Channel protocol. FC-0 Fibre Channel layer 0. Specifies the physical signalling used in Fibre Channel, as well as cable plants, media types, and transmission speeds.
FC-1
Fibre Channel layer 1. Specifies the IBM patented 8B/10B data encoding used in Fibre Channel.
FC-2
Fibre Channel layer 2. Specifies the frame format, Sequence/Exchange management, and Ordered Set usage in Fibre Channel.
FC-3
Fibre Channel layer 3. Specifies services provided for multiple N_Ports in a single node.
FC-4
Fibre Channel layer 4. Specifies mapping of Upper Level Protocols such as SCSI and IP onto the Fibre Channel Protocol.
Fill Word
The Primitive Signal is used by L_Ports to be transmitted in between Frames. This may be Idle or ARBx, depending on which, if any, L_Ports are Arbitrating for Loop access, and will not necessarily be the same for all L_Ports on the Loop at any given time.
FL_Port
Fabric-Loop port. An F_Port which is capable of supporting an attached Arbitrated Loop. An FL_Port on a Loop will have the AL_PA hex'00', giving the Fabric highest priority access to the Loop. An FL_Port is the gateway to the Fabric for NL_Ports on a Loop.
F/NL_Port
An NL_Port which is capable of providing certain Fabric services to other NL_Ports on a Loop in the absence of a Fabric. This NL_Port will respond to requests to open communication with AL_PA hex'00', even though it may actually have another value for its AL_PA.
F_Port
Fabric port. A port on a fabric switch to which N_Ports may be directly connected. An F_Port is uses the address identifier hex'FFFFFE'.
Frame
The basic unit of communication between two N_Ports. Frames are composed of a starting delimiter (SOF), a header, the payload, the Cyclic Redundancy Check (CRC), and an ending delimiter (EOF). The SOF and EOF contain the Special Character and are used to indicate where the frame begins and ends. The 24-byte header contains information about the frame, including the S_ID, D_ID, routing information, the type of data contained in the payload, and sequence/exchange management information. The payload contains the actual data to be transmitted, and may be 0-2112 bytes in length. The CRC is a 4-byte field used for detecting bit errors in the received frame.
F_RJT
Fabric Port Reject Frame. This Frame is issued by the Fabric to indicate that delivery of a particular frame is being denied. Some reasons for issuing an F_RJT include: Class not supported; invalid header field(s); and N_Port unavailable.
G H I
Idle
An Ordered Set transmitted continuously over a link when no data are being transmitted. Idle is transmitted to maintain an active link over a fibre and lets the receiver and transmitter maintain bit, byte, and word synchronization.
Intermix
A service in which Class 2 and Class 3 frames may be delivered to an N_Port which has a Class 1 dedicated connection open. The Class 2 and 3 frames are delivered during times which no Class 1 frames are being delivered on the connection.
J K L
Link Service
Link Services are facilities used between an N_Port and a Fabric or between two N_Ports and are used to for such purposes as Login, Sequence and Exchange management, and maintaining connections.
LIP
Loop Initialization Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to (re)initialize the Loop.
LIFA
Loop Initialization Fabric Assigned Frame. This is the first Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which have been assigned their AL_PA by the Fabric will select their AL_PA's in this frame as it makes its way around the Loop.
LIHA
Loop Initialization Hard Assigned Frame. This is the third Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which have been programmed to select a particular AL_PA (if available) by the manufacturer will select their AL_PA's in this frame as it makes its way around the Loop.
LILP
Loop Initialization Loop Position Frame. This is the second Frame transmitted in the Loop initialization process after all L_Ports have selected an AL_PA (after LISA has been around the loop). This Frame is transmitted around the Loop so that all L_Ports may know the relative position of all other L_Ports around the Loop. Support for this Frame by an L_Port is optional.
LIPA
Loop Initialization Previously Assigned Frame. This is the second Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which had an AL_PA prior to the Loop initialization will select their AL_PA's in this frame as it makes its way around the Loop.
LIRP
Loop Initialization Report Position Frame. This is the first Frame transmitted in the Loop initialization process after all L_Ports have selected an AL_PA (after LISA has been around the loop). This Frame is transmitted around the Loop so that all L_Ports report their relative physical position on the loop. Support for this Frame by an L_Port is optional.
LISA
Loop Initialization Soft Assigned Frame. This is the fourth Frame transmitted in the Loop initialization process after a temporary Loop master has been selected. L_Ports which did not select an AL_PA in any of the previous Loop Initialization Frames (LIFA, LIPA, or LIHA) will select their AL_PA's in this frame as it makes its way around the Loop.
LISM
Loop Initialization Select Master Frame. This Frame applies only to the Arbitrated Loop topology. It is the first frame transmitted in the initialization process in which L_Ports select an AL_PA. It is used to select a temporary Loop master, or the L_Port that will subsequently initiate transmission of the remaining initialization frames (LIFA, LIPA, LIHA, LISA, LIRP, and LILP).
LPB
Loop Port Bypass Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to bypass the L_Port it is directed to. For example, if Port A suspects that Port B is malfunctioning, Port A can send an LPB to Port B so that Port B will only retransmit everything it receives, and will not be active on the Loop.
LPE
Loop Port Enable Primitive Sequence. This Primitive Sequence applies only to the Arbitrated Loop topology. It is transmitted by an L_Port to enable an L_Port which has been bypassed with the LPB Primitive Sequence.
L_Port
Loop port. Generic term for an NL_Port or FL_Port, i.e., any Fibre Channel port which supports the Arbitrated Loop topology.
LPSM
Loop Port State Machine. This is a state machine maintained by an L_Port to track its behavior through different phases of Loop operation, i.e., how it behaves when it is arbitrating for Loop access, how it behaves when it has control of the Loop, etc.
LR
Link Reset Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. The expected response to a port sending LR is the LRR Primitive Sequence.
LRR
Link Reset Response Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent in response to the LR Primitive Sequence. The expected response to a port sending LRR is Idle.
M
MRK
Mark Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. It is transmitted by an L_Port for synchronization purposes and its use is vendor specific.
N
NL_Port
Node-Loop port. An N_Port which can operate on the Arbitrated Loop topology.
Nonparticipating Mode
An L_Port will enter the nonparticipating mode if there are more than 127 devices on a Loop, and it thus cannot acquire an AL_PA. An L_Port may also voluntarily enter the nonparticipating mode if it is still physically connected to the Loop, but wishes not to participate. An L_Port in the nonparticipating mode is not capable of generating Transmission Words on the Loop and may only retransmit words received on its inbound fibre.
NOS
Not Operational Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent to indicate that that transmitting port has detected a link failure or is offline. The expected response to a port sending NOS is the OLS Primitive Sequence.
N_Port
Node port. A port on a computer, disk drive, etc. through which the device does its Fibre Channel communication.
N_Port Name
An 8-byte manufacturer-assigned value which uniquely identifies the N_Port throughout the world.
O
OLS
Offline Primitive Sequence. This Primitive Sequence is used during link initialization between two N_Ports in the Point-to-point topology or an N_Port and an F_Port in the Fabric topology. It is sent to indicate that the transmitting port is attempting to initialize the link, has recognized the NOS Primitive Sequence, or is going offline. The expected response to a port sending OLS is the LR Primitive Sequence.
OPN
Open Primitive Signal. This Primitive Signal applies only to the Arbitrated Loop topology. The OPN Primitive Signal is sent by an L_Port that has won the arbitration process to open communication with with one or more other ports on the Loop.
Ordered Set
A 4-byte Transmission Word which has the Special Character as its first Transmission Character. An Ordered Set may be a Frame Delimiter, a Primitive Signal, or a Primitive Sequence. Ordered Sets are used to distinguish Fibre Channel control information from data.
Originator
The N_Port which originated an Exchange.
OX_ID
Originator Exchange Identifier. A 2-byte field in the frame header used by the originator of an Exchange to identify frames as being part of a particular Exchange.
P
Participating Mode
The normal operating mode for an L_Port on a Loop. An L_Port in this mode has acquired an AL_PA and is capable of communicating on the Loop.
Primitive Sequence
An Ordered Set transmitted repeatedly and used to establish and maintain a link. LR, LRR, NOS, and OLS are Primitive Sequences used to establish an active link in a connection between two N_Ports or an N_Port and an F_Port. LIP, LPB, and LPE are Primitive Sequences used in the Arbitrated Loop topology for initializing the Loop and enabling or disabling an L_Port.
Primitive Signal
An Ordered Set used to indicate an event. Idle and R_RDY are used in all three topologies. ARB, OPN, CLS, and MRK are used only in the Arbitrated Loop topology.
Private Loop
An Arbitrated Loop which stands on its own, i.e., it is not connected to a Fabric.
Private NL_Port
An NL_Port which only communicates with other ports on the loop, not with the Fabric. Note that a Private NL_Port may exist on either a Private Loop or a Public Loop.
Public Loop
An Arbitrated Loop which is connected to a Fabric.
Public NL_Port
An NL_Port which may communicate with other ports on the Loop as well as through an FL_Port to other N_Ports connected to the Fabric.
Q R
Responder
The N_Port to with which an Exchange originator wishes to communicate.
RX_ID
Responder Exchange Identifier. A 2-byte field in the frame header used by the responder of the Exchange to identify frames as being part of a particular Exchange.
S
Sequence
A group of related frames transmitted unidirectionally from one N_Port to another.
SEQ_ID
Sequence Identifier. A 1-byte field in the frame header used to identify which Sequence of an Exchange a particular frame belongs to.
Sequence Initiator
The N_Port which began a new Sequence and transmits frames to another N_Port.
Sequence Recipient
The N_Port to which a particular Sequence of data frames is directed.
S_ID
Source Identifier. A 3-byte field in the frame header used to indicate the address identifier of the N_Port the frame was sent from.
SOF
Start of Frame delimiter. This Ordered Set is always the first Transmission Word of a Frame. It is used to indicate that a Frame will immediately follow and indicates which class of service the Frame will use.
Special Character
A special 10-bit Transmission Character which does mot have a corresponding 8-bit value, but is still considered valid. The Special Character is used to indicate that a particular Transmission Word is an Ordered Set. The Special Character is the only Transmission Character to have 5 1's or 0's in a row. The Special Character is also referred to as K28.5 when using K/D format.
T
Transmission Character
A (valid or invalid) 10-bit character transmitted serially over the fibre. Valid Transmission Characters are determined by the 8B/10B encoding specification.
Transmission Word
A string of four consecutive Transmission Characters.
U
ULP
Upper Level Protocol. The protocol which runs on top of Fibre Channel through the FC-4 layer. Typical ULPs running over Fibre Channel are Small Computer System Interface (SCSI), Internet Protocol (IP), High Performance Parallel Interface (HIPPI), and Intelligent Peripheral Interface (IPI).
The IBM patented encoding method used for encoding 8-bit data bytes to 10-bit Transmission Characters. Data bytes are converted to Transmission Characters to improve the physical signal such that the following benefits are achieved: bit synchronization is more easily achieved, design of receivers and transmitters is simplified, error detection is improved, and control characters (i.e., the Special Character) can be distinguished from data characters.
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