OpenVMS I/O User's Reference Manual

Document revision date: 15 July 2002

OpenVMS I/O User's Reference Manual

Contents

Index

Note

The EL device is the emulated LAN device associated with the physical ATM device.

9.2.3 Supported Industry Standards

Ethernet drivers support the following features:

Ethernet and IEEE 802.3 packet format
Physical layer identified as type 10Base5 (ThickWire), 10Base2 (ThinWire), and 10BaseT (twisted pair)
Fast Ethernet and IEEE 802.3u packet format
Fast Ethernet physical layer identified as type 100BaseTX
Gigabit Ethernet and IEEE 802.3z packet format
Gigabit Ethernet's physical layer is identified as type 1000BaseT for unshielded twisted pair (UTP), 1000Base-SX for multimode fiber-optic cables.
Gigabit Ethernet maximum frame size of 9018 bytes (limited to 7552 bytes in OpenVMS Version 7.3-1 and earlier)

FDDI drivers support the following features:

FDDI packet format
Transmission and reception of frame control (FC) priority

Token Ring drivers support the following features:

IEEE 802.5 packet format

ATM drivers over ELAN support the following features:

Ethernet and IEEE 802.3 packet format
UNI Version 3.0 or 3.1 signaling protocol
LAN emulation (LANE) Version 1.0
Maximum frame sizes of 1516, 4544, and 9234 bytes

All LAN drivers support the following features:

802.2 packet format
IEEE 802.2 Class I service including the unnumbered information (UI), exchange identification (XID) commands and responses, and TEST commands and responses
IEEE 802.2 Class II service may be specified where the functions are provided by the user application
6-byte destination and source address fields

Contrary to the IEEE 802.2 Standard, the Global DSAP (FF) must be enabled as a Group SAP to receive messages with the Global DSAP in the destination SAP field.

FDDI conforms to the ANSI Standards defined in the following documents:

ANSI X3.139-1987 FDDI Media Access Control (MAC)
ANSI X3.148-1988 FDDI Physical Layer Protocol (PHY)
ANSI X3.166-1990 FDDI Physical Layer Medium Dependent (PMD)

9.3 LAN Controller Characteristics

System software and user applications communicate with other systems through the LAN controllers using the QIO interface defined by the OpenVMS LAN driver software. This interface is described later in this chapter. The LAN driver software allows communication with the different LAN technologies in a consistent manner.

The LAN controllers implement the Ethernet, FDDI, Token Ring, and ATM specifications. The Ethernet specification is described in The Ethernet-Data Link Layer and Physical Specification. The FDDI specifications are available from ANSI. The Token Ring specifications are available from IEEE. The ATM LAN Emulation specifications are available from the ATM Forum. The Classical IP over ATM specification (RFC 1577) is available from the Internet Engineering Task Force (IETF).

Ethernet includes Fast Ethernet (802.3u) and Gigabit Ethernet (802.3z). See Section 9.4 and Section 9.5 for more information.

Ethernet, FDDI, Token Ring, and ATM networks can be configured to form a single extended LAN using FDDI-Ethernet bridges, FDDI and Ethernet switches, Token Ring bridges and routers, and ATM switches. This allows applications running on a system connected by a LAN controller of one technology to communicate with applications running on another system connected by a different type of LAN controller.

9.4 Fast Ethernet LAN Devices (Alpha Only)

Fast Ethernet (802.3u) is an extension of the IEEE 802.3 standard. It typically runs over twisted-pair wiring. It increases the data transmission rate from 10 to 100 Mb/s and decreases the maximum length of a network segment. Fast Ethernet controllers allow either 10 or 100 Mb/s operation for compatibility with existing 10 Mb/s controllers.

Table 9-3 shows the types of cabling used for Fast Ethernet.

Table 9-3 Fast Ethernet Cabling
Cable Description

100BaseTX Works with twisted-pair cabling. It provides full-duplex communication, using only two of the four pairs of wires.

100BaseFX Uses fiber optic cabling. Used mainly for backbones by connecting Fast Ethernet repeaters placed around a building. It gives protection from electromagnetic noise and increases security. It also allows longer distances between network devices.

**Table 9-3 Fast Ethernet Cabling**
Cable	Description
100BaseTX	Works with twisted-pair cabling. It provides full-duplex communication, using only two of the four pairs of wires.
100BaseFX	Uses fiber optic cabling. Used mainly for backbones by connecting Fast Ethernet repeaters placed around a building. It gives protection from electromagnetic noise and increases security. It also allows longer distances between network devices.

9.4.1 Fast Ethernet NIC---DE500

Table 9-4 lists and describes the devices and drivers of the Fast Ethernet adapters on Alpha PCI-based systems that the OpenVMS operating system supports.

Table 9-4 DE500 Adapters
Device Driver Description

DE500--XA SYS$EWDRIVER.EXE 10,100 Mb UTP, no auto-negotiation

DE500--AA SYS$EWDRIVER.EXE 10,100 Mb UTP

DE500--BA SYS$EWDRIVER_DE500BA.EXE 10,100 Mb UTP

DE500--FA SYS$EWDRIVER_DE500BA.EXE Multimode fiber, 100 Mb

**Table 9-4 DE500 Adapters**
Device	Driver	Description
DE500--XA	SYS$EWDRIVER.EXE	10,100 Mb UTP, no auto-negotiation
DE500--AA	SYS$EWDRIVER.EXE	10,100 Mb UTP
DE500--BA	SYS$EWDRIVER_DE500BA.EXE	10,100 Mb UTP
DE500--FA	SYS$EWDRIVER_DE500BA.EXE	Multimode fiber, 100 Mb

9.4.2 Fast Ethernet NIC---DE600

The Intel 82558 and 82559 are PCI Ethernet chips, which are used in the DE60x series of Compaq Ethernet NICs. These NICs are equivalent to the Compaq standard numbered NICs, NC31xx series.

Each NIC is a 10BaseT or 100BaseTX PCI Ethernet NIC. The LAN driver that controls the NIC is SYS$EIDRIVER.EXE.

Table 9-5 lists and describes the devices and drivers of each Fast Ethernet adapter.

Table 9-5 DE600 Adapters
Device Driver Description

DE600--AA SYS$EIDRIVER.EXE 10,100 Mb, UTP

DE602--AA SYS$EIDRIVER.EXE 10,100 Mb, UTP, dual

DE602--BA SYS$EIDRIVER.EXE 10,100 Mb, UTP. dual

DE602--BB SYS$EIDRIVER.EXE 10,100 Mb, UTP, dual

DE602--TA SYS$EIDRIVER.EXE 10,100 Mb, UTP, daughter card

DE602--FA SYS$EIDRIVER.EXE 100 Mbit multimode fiber, daughter card

Embedded 82559ER SYS$EIDRIVER.EXE 10,100 Mbit UTP

**Table 9-5 DE600 Adapters**
Device	Driver	Description
DE600--AA	SYS$EIDRIVER.EXE	10,100 Mb, UTP
DE602--AA	SYS$EIDRIVER.EXE	10,100 Mb, UTP, dual
DE602--BA	SYS$EIDRIVER.EXE	10,100 Mb, UTP. dual
DE602--BB	SYS$EIDRIVER.EXE	10,100 Mb, UTP, dual
DE602--TA	SYS$EIDRIVER.EXE	10,100 Mb, UTP, daughter card
DE602--FA	SYS$EIDRIVER.EXE	100 Mbit multimode fiber, daughter card
Embedded 82559ER	SYS$EIDRIVER.EXE	10,100 Mbit UTP

9.5 Gigabit Ethernet LAN Devices (Alpha Only)

Gigabit Ethernet (802.3z) is an extension of the IEEE 802.3 standard. It runs over fiber-optic cabling and twisted-pair wiring. It increases the data transmission rate to 1000 Mb/s. The frame formats are identical to Ethernet and Fast Ethernet which allows good interoperability across these technologies. Gigabit Ethernet is suitable as a high-speed backbone interconnect but may be used to connect high-performance workstations or systems that need the increased bandwidth. Twisted-pair Gigabit controllers allow either 10, 100, or 1000 Mb/s operation for compatibility with existing 10 or 100 Mb/s networks.

Table 9-6 shows the types of cabling used for Gigabit Ethernet.

Table 9-6 Gigabit Ethernet Cabling
Cable Description

1000Base-SX Works with multimode fiber optic cabling. Used mainly for shorter backbone applications. It supports distances of up to 550 meters.

1000Base-LX Works with singlemode fiber optic cabling. Used mainly for longer fiber backbones and campus backbones. It supports distances of up to 5 kilometers.

1000BaseT Works with unshielded copper cabling. Used mainly for short distance applications. It supports a signal transmission over four pairs of category 5 unshielded twisted pair (UTP), covering distances up to 100 meters, or networks with a diameter of 200 meters.

**Table 9-6 Gigabit Ethernet Cabling**
Cable	Description
1000Base-SX	Works with multimode fiber optic cabling. Used mainly for shorter backbone applications. It supports distances of up to 550 meters.
1000Base-LX	Works with singlemode fiber optic cabling. Used mainly for longer fiber backbones and campus backbones. It supports distances of up to 5 kilometers.
1000BaseT	Works with unshielded copper cabling. Used mainly for short distance applications. It supports a signal transmission over four pairs of category 5 unshielded twisted pair (UTP), covering distances up to 100 meters, or networks with a diameter of 200 meters.

OpenVMS supports the DEGPA Gigabit Ethernet LAN controller on Alpha PCI-based systems.

9.6 Gigabit Ethernet NIC---DEGPA

The DEGPA series of Compaq Gigabit Ethernet NICs uses the Tigon2 PCI Gigabit Ethernet chip. Each NIC is a 10BaseT, 100BaseTX, 1000BaseTX, or 1000BaseSX PCI Ethernet NIC. The LAN driver that controls the DEGPA NIC is SYS$EW1000A.EXE.

Table 9-7 lists and describes the devices and drivers of the DEGPA.

Table 9-7 DEGPA Devices
Device Driver Description

DEGPA--SA SYS$EW1000A.EXE Multimode fiber

DEGPA--TA SYS$EW1000A.EXE 10,100,1000 Mb UTP

**Table 9-7 DEGPA Devices**
Device	Driver	Description
DEGPA--SA	SYS$EW1000A.EXE	Multimode fiber
DEGPA--TA	SYS$EW1000A.EXE	10,100,1000 Mb UTP

9.6.1 DEGPA Internal Counters

With LANCP, the command SHOW DEVICE/INTERNAL_COUNTERS EWc displays the entire set of internal counters maintained by the driver. Some counters are special debug counters. These are not displayed unless the additional qualifier /DEBUG is specified. The debug counters include the address of the status block, statistics block, and the contents of significant CSRs. The significant CSRs are read just prior to returning the internal counters to LANCP and when the system is shutting down.

The LAN$SDA SDA extension also displays the complete set of internal counters with the command LAN INTERNAL/DEVICE=EWc. This extension includes the debug counters.

The following sections present various groupings of internal counters. The definition of these counters may change from one driver version to the next.

9.6.2 Basic Counters

Table 9-8 describes the basic counters displayed by the DEGPA Gigabit Ethernet NIC.

Table 9-8 DEGPA Status and Counters
Status/Counters Meaning

Driver version The driver version number is numbered 1...n that usually is identical to the x--n ID displayed by an ANA/IMAGE of the driver image. It includes variant information, if any. The full driver version includes the target OpenVMS release and is displayed by SDA LAN/DEV=EWA in the quadword driver version field.

Firmware version The version number is in hexadecimal; it is read from right to left.

Device interrupts The number of times the interrupt service routine was called.

Events completed The number of events completed from the event ring.

Link transitions The total number of link state up and link state down events.

Transmit timeouts The number of times the driver has timed out a transmit and has reset the device and completed outstanding I/O requests with error status.

Initialization timeouts The number of times the driver has timed out an initialization request and has reset the device and completed outstanding I/O requests with error status.

Resets issued The number of times the driver has reset the device.

Initialization done The number of times the driver performed the device initialization procedure (done when the first user is started).

Initialization (with or without map registers) The number of unit initializations executed, since unit initialization is only executed once, this counter will be one. Which counter is set depends whether map registers were used to map the device data structures.

User change requests The number of user startup and shutdown requests processed by the driver, generally one or two when a user starts up, and one when a user stops.

PTE to PFN translations The number of times a global page was encountered during a chained transmit request, causing the driver to convert an invalid PTE to a valid PFN.

Transmits queued The number of transmit requests queued because the link was not available or because too many transmit requests were already outstanding.

Transmit errors (too few segments) The number of transmit requests completed with error status (SS$_INCSEGTRA) because the application did not specify the transmit buffer completely.

Transmit copies (too many segments) The number of transmit requests that exceeded the maximum number of chain segments that the driver can handle; the counter then copied some of them to a temporary buffer so that it could transmit the packet.

Jumbo transmits issued The number of transmit requests with a packet length exceeding 1514 bytes, excluding CRC.

Transmits issued (using map registers) The number of transmit requests that were described to the device using map registers because part of the request existed in memory outside the DMA window.

Jumbo receives issued The number of jumbo receive buffers allocated and given to the device.

Receives issued (using map registers) The number of receive buffers that were described to the device using map registers, because part of the request existed in memory outside the DMA window, because the receive buffer crossed a page boundary, or because the receive buffer was a jumbo buffer.

Soft errors The number of times errors were recovered in the driver by resetting the device.

Commands outstanding The number of commands outstanding to the device.

Commands queued The number of commands that have been queued to the device.

Command pending mask The commands that the driver has not yet issued to the device.

Invalid command The event code of the last event.

Unexpected event The event code of the last event that was not recognized.

Rescheduled forks The number of times that a rescheduled fork was done. In transmit and receive processing, the driver limits the amount of time spent in the fork process before rescheduling.

Standard receive buffers The number of 1518 byte receive buffers owned by the device.

Standard receive buffer deallocations The number of 1518 byte buffer deallocations done by the driver because the number of outstanding buffers exceeded the maximum number allowed by the driver.

Jumbo receive buffers (current) The number of 7552 byte receive buffers owned by the device.

Jumbo receive buffers (minimum) The minimum number of 7552 byte receive buffers owned by the device. This is set to 1 initially. After the first jumbo receive, the driver sets the minimum to 32.

Jumbo receive buffer allocations The number of jumbo receive buffer allocations done by the driver.

Jumbo receive buffer deallocations The number of 7552 byte buffer deallocations done by the driver because the number of outstanding buffers exceeded the maximum number allowed by the driver.

Standard buffer size (bytes) The size of the standard receive buffers. It is the CSMA/CD packet size, 1518 bytes including header and CRC, plus the overhead of the receive buffer structure (640 bytes).

Standard packet size (bytes) This is the CSMA/CD size (1518 bytes).

Jumbo buffer size (bytes) The size of the jumbo receive buffers. The device allows up to 9018-byte packets, including header and CRC, plus the 640-byte receive buffer structure overhead. But the driver limits the buffer size to the maximum size supported by the pool lookaside lists, which is 8192 bytes in current and recent OpenVMS releases. In a future release, the buffer size will be 9018 plus 640 bytes of overhead, rounded up to the next 64-byte boundary, to accommodate the full jumbo packet size.

Requested speed The speed requested by a user.

Requested link value The link control bits set by the driver to use during link initialization.

Current link state The current link state determined by the device.

Jumbo packets The size of jumbo frames, which is 7552 bytes. The SYSGEN parameter LAN_FLAGS bit 6 or the LANCP command SET DEV/[NO]JUMBO determines whether the maximum user data size for VCI applications is the standard size (1518 bytes less header and CRC) or jumbo size. The default is disabled, LAN_FLAGS bit 6 set to zero.

Link autonegotiation Determines whether the link state that the driver requests the device to use allows autonegotiation. The SYSGEN parameter LAN_FLAGS bit 5 or the LANCP command SET DEV/[NO]AUTO determines the setting. The default is enabled.

DMA operation Displays the result of the determination by the device whether it is in a 32-bit or 64-bit PCI bus.

Current PCI state The current value of the PCI state register which controls the DMA hardware and other PCI characteristics.

Transmit coalesce value Transmit interrupts are generated every 32 "coalesce value" transmit completions, but no later than 50 "interrupt delay" microseconds after completion of a packet.

Receive coalesce value Receive interrupts are generated every 32 "coalesce value" receive completions, but no more than 50 "interrupt delay" microseconds after receipt of a packet.

Transmit interrupt delay Transmit interrupts are generated every 32 "coalesce value" transmit completions, but no more than 50 "interrupt delay" microseconds after completion of a packet.

Receive interrupt delay Receive interrupts are generated every 32 "coalesce value" receive completions, but no more than 50 "interrupt delay" microseconds after receipt of a packet.

Current EXE$GL_ABSTIM_TICS The current time in 10-millisecond ticks of the counters request from LANCP.

Statistics EXE$GL_ABSTIM_TICS The time in 10-millisecond ticks of the last statistics update from the device.

**Table 9-8 DEGPA Status and Counters**
Status/Counters	Meaning
Driver version	The driver version number is numbered 1...n that usually is identical to the x--n ID displayed by an ANA/IMAGE of the driver image. It includes variant information, if any. The full driver version includes the target OpenVMS release and is displayed by SDA LAN/DEV=EWA in the quadword driver version field.
Firmware version	The version number is in hexadecimal; it is read from right to left.
Device interrupts	The number of times the interrupt service routine was called.
Events completed	The number of events completed from the event ring.
Link transitions	The total number of link state up and link state down events.
Transmit timeouts	The number of times the driver has timed out a transmit and has reset the device and completed outstanding I/O requests with error status.
Initialization timeouts	The number of times the driver has timed out an initialization request and has reset the device and completed outstanding I/O requests with error status.
Resets issued	The number of times the driver has reset the device.
Initialization done	The number of times the driver performed the device initialization procedure (done when the first user is started).
Initialization (with or without map registers)	The number of unit initializations executed, since unit initialization is only executed once, this counter will be one. Which counter is set depends whether map registers were used to map the device data structures.
User change requests	The number of user startup and shutdown requests processed by the driver, generally one or two when a user starts up, and one when a user stops.
PTE to PFN translations	The number of times a global page was encountered during a chained transmit request, causing the driver to convert an invalid PTE to a valid PFN.
Transmits queued	The number of transmit requests queued because the link was not available or because too many transmit requests were already outstanding.
Transmit errors (too few segments)	The number of transmit requests completed with error status (SS$_INCSEGTRA) because the application did not specify the transmit buffer completely.
Transmit copies (too many segments)	The number of transmit requests that exceeded the maximum number of chain segments that the driver can handle; the counter then copied some of them to a temporary buffer so that it could transmit the packet.
Jumbo transmits issued	The number of transmit requests with a packet length exceeding 1514 bytes, excluding CRC.
Transmits issued (using map registers)	The number of transmit requests that were described to the device using map registers because part of the request existed in memory outside the DMA window.
Jumbo receives issued	The number of jumbo receive buffers allocated and given to the device.
Receives issued (using map registers)	The number of receive buffers that were described to the device using map registers, because part of the request existed in memory outside the DMA window, because the receive buffer crossed a page boundary, or because the receive buffer was a jumbo buffer.
Soft errors	The number of times errors were recovered in the driver by resetting the device.
Commands outstanding	The number of commands outstanding to the device.
Commands queued	The number of commands that have been queued to the device.
Command pending mask	The commands that the driver has not yet issued to the device.
Invalid command	The event code of the last event.
Unexpected event	The event code of the last event that was not recognized.
Rescheduled forks	The number of times that a rescheduled fork was done. In transmit and receive processing, the driver limits the amount of time spent in the fork process before rescheduling.
Standard receive buffers	The number of 1518 byte receive buffers owned by the device.
Standard receive buffer deallocations	The number of 1518 byte buffer deallocations done by the driver because the number of outstanding buffers exceeded the maximum number allowed by the driver.
Jumbo receive buffers (current)	The number of 7552 byte receive buffers owned by the device.
Jumbo receive buffers (minimum)	The minimum number of 7552 byte receive buffers owned by the device. This is set to 1 initially. After the first jumbo receive, the driver sets the minimum to 32.
Jumbo receive buffer allocations	The number of jumbo receive buffer allocations done by the driver.
Jumbo receive buffer deallocations	The number of 7552 byte buffer deallocations done by the driver because the number of outstanding buffers exceeded the maximum number allowed by the driver.
Standard buffer size (bytes)	The size of the standard receive buffers. It is the CSMA/CD packet size, 1518 bytes including header and CRC, plus the overhead of the receive buffer structure (640 bytes).
Standard packet size (bytes)	This is the CSMA/CD size (1518 bytes).
Jumbo buffer size (bytes)	The size of the jumbo receive buffers. The device allows up to 9018-byte packets, including header and CRC, plus the 640-byte receive buffer structure overhead. But the driver limits the buffer size to the maximum size supported by the pool lookaside lists, which is 8192 bytes in current and recent OpenVMS releases. In a future release, the buffer size will be 9018 plus 640 bytes of overhead, rounded up to the next 64-byte boundary, to accommodate the full jumbo packet size.
Requested speed	The speed requested by a user.
Requested link value	The link control bits set by the driver to use during link initialization.
Current link state	The current link state determined by the device.
Jumbo packets	The size of jumbo frames, which is 7552 bytes. The SYSGEN parameter LAN_FLAGS bit 6 or the LANCP command SET DEV/[NO]JUMBO determines whether the maximum user data size for VCI applications is the standard size (1518 bytes less header and CRC) or jumbo size. The default is disabled, LAN_FLAGS bit 6 set to zero.
Link autonegotiation	Determines whether the link state that the driver requests the device to use allows autonegotiation. The SYSGEN parameter LAN_FLAGS bit 5 or the LANCP command SET DEV/[NO]AUTO determines the setting. The default is enabled.
DMA operation	Displays the result of the determination by the device whether it is in a 32-bit or 64-bit PCI bus.
Current PCI state	The current value of the PCI state register which controls the DMA hardware and other PCI characteristics.
Transmit coalesce value	Transmit interrupts are generated every 32 "coalesce value" transmit completions, but no later than 50 "interrupt delay" microseconds after completion of a packet.
Receive coalesce value	Receive interrupts are generated every 32 "coalesce value" receive completions, but no more than 50 "interrupt delay" microseconds after receipt of a packet.
Transmit interrupt delay	Transmit interrupts are generated every 32 "coalesce value" transmit completions, but no more than 50 "interrupt delay" microseconds after completion of a packet.
Receive interrupt delay	Receive interrupts are generated every 32 "coalesce value" receive completions, but no more than 50 "interrupt delay" microseconds after receipt of a packet.
Current EXE$GL_ABSTIM_TICS	The current time in 10-millisecond ticks of the counters request from LANCP.
Statistics EXE$GL_ABSTIM_TICS	The time in 10-millisecond ticks of the last statistics update from the device.

9.6.3 Medium Access Control (MAC) Counter Statistics

Table 9-9 describes the definitions of MACs counter statistics that are derived from the RFC 1643 standards.

Table 9-9 MAC Counter Statistics
Counter Statistics Meaning

Alignment errors The number of packets received with CRC errors and that are not an integral number of bytes long. These packets are discarded and are then counted by the device.

FCS errors The number of packets received with CRC errors and that are an integral number of bytes long. These packets are discarded and are then counted by the device.

Single collisions The number of successfully transmitted packets which encountered exactly one collision during transmission (successful after retransmit). These occur in half-duplex mode only.

Multiple collisions The number of successfully transmitted packets that encountered more than one collision during transmission (successful after multiple retransmits). These occur in half-duplex mode only.

SQE test errors The number of SQE test errors generated after successful transmission. These are also called heartbeat errors. Some network hardware does not support this test function, so this error happens on every transmit. These occur in half-duplex mode only.

Deferred transmits The number of successful transmits that were delayed because the medium was busy. These occur in half-duplex mode only.

Late collisions The number of times a collision was detected longer than 512 bit-times into the transmission of a packet. The transmit fails. These occur in half-duplex mode only.

Excessive collisions The number of transmits which failed due to excessive collisions. These occur in half-duplex mode only.

Internal MAC transmit errors The number of transmits that failed because of an internal MAC sublayer error that is not late collision, excessive collisions, or carrier sense error.

Carrier sense errors The number of transmits that failed because carrier was not present during any or all of the transmission attempt.

Frame too long errors The number of received frames that were longer than the jumbo packet size. These packets are discarded and are then counted by the device.

Internal MAC receive errors The number of receive packets discarded because of an internal MAC sublayer error that is not frame too long, alignment error, or FCS error. These packets are discarded and are then counted by the device.

**Table 9-9 MAC Counter Statistics**
Counter Statistics	Meaning
Alignment errors	The number of packets received with CRC errors and that are not an integral number of bytes long. These packets are discarded and are then counted by the device.
FCS errors	The number of packets received with CRC errors and that are an integral number of bytes long. These packets are discarded and are then counted by the device.
Single collisions	The number of successfully transmitted packets which encountered exactly one collision during transmission (successful after retransmit). These occur in half-duplex mode only.
Multiple collisions	The number of successfully transmitted packets that encountered more than one collision during transmission (successful after multiple retransmits). These occur in half-duplex mode only.
SQE test errors	The number of SQE test errors generated after successful transmission. These are also called heartbeat errors. Some network hardware does not support this test function, so this error happens on every transmit. These occur in half-duplex mode only.
Deferred transmits	The number of successful transmits that were delayed because the medium was busy. These occur in half-duplex mode only.
Late collisions	The number of times a collision was detected longer than 512 bit-times into the transmission of a packet. The transmit fails. These occur in half-duplex mode only.
Excessive collisions	The number of transmits which failed due to excessive collisions. These occur in half-duplex mode only.
Internal MAC transmit errors	The number of transmits that failed because of an internal MAC sublayer error that is not late collision, excessive collisions, or carrier sense error.
Carrier sense errors	The number of transmits that failed because carrier was not present during any or all of the transmission attempt.
Frame too long errors	The number of received frames that were longer than the jumbo packet size. These packets are discarded and are then counted by the device.
Internal MAC receive errors	The number of receive packets discarded because of an internal MAC sublayer error that is not frame too long, alignment error, or FCS error. These packets are discarded and are then counted by the device.

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