Document revision date: 15 July 2002

Table 9-22 lists and describes the counters for the receive list placement state machine.

Table 9-22 Receive List Placement State Machine

Counter	Meaning
Frames received onto return ring 1..16	The number of frames received onto each of the return rings.
Frames discarded using filters	The number of frames received but discarded after validation by the receive filters.
DMA write queue full	The number of times the DMA write queue was full.
DMA high priority write queue full	The number of times the DMA write high-priority queue was full.
No more receive BDs	The number of times the NIC ran out of receive buffer descriptors.
Inbound discards	The number of inbound packets that were chosen to be discarded even though no errors had been detected to prevent their being deliverable to a higher-layer protocol. One possible reason for discarding such a packet could be to free up buffer space.
Inbound errors	The number of inbound packets that contained errors that prevented them from being deliverable to a higher-layer protocol.
Receive threshold hit	The number of times the receive max coalesce frames threshold was reached, resulting in a status block update and interrupt.

9.7.4.4 Statistics: Send Data Initiator State Machine

Table 9-23 lists and describes the counters for the send data initiator state machine.

Table 9-23 Send Data Initiator State Machine

Counter	Meaning
Frames sent from send ring 1..16	The number of frames sent from each of the send rings.
DMA read queue full	The number of times the DMA read queue was full.
DMA high priority read queue full	The number of times the DMA read high-priority queue was full.
Send data completion queue full	The number of times the send data completion flow-thorough-queue (FTQ) was full.

9.7.4.5 Statistics: Host Coalescing State Machine

Table 9-24 lists the counters for the host coalescing state machine statistics.

Table 9-24 Host Coalescing State Machine

Counter	Meaning
Send producer index updates	The number of times the NIC has seen updates to any send producer ring index.
Ring status updates	The number of times the status block was updated (written to host memory). If the driver is not currently in its interrupt service routine, an interrupt is generated after the update.
Interrupts generated	The number of interrupts generated by the NIC.
Interrupts avoided	The number of interrupts avoided by the NIC (because of interrupt mitigation).
Send threshold hit	The number of times the send max coalesce frames threshold was reached, resulting in a status block update and interrupt.

9.7.5 Fork Delay Debug Data

To help determine whether the buffering requirements of the driver and the NIC are sufficient for the system configuration, the driver records the amount of time from fork scheduled to the time the fork is actually run. The data is recorded in 10-millisecond increments from 10 to 310 milliseconds.

This data can be used in conjunction with the number of packets discarded because there were insufficient buffers to determine whether the buffering settings of the driver (minimum and maximum receive buffers) and the amount of buffering on the NIC are sufficient for normal operation. If packets are being discarded, the buffering should be increased until the number of packets lost is minimal.

9.7.6 Driver Messages

The following is the last 32 driver messages broadcast to the console, describing events such as link transitions, changes to jumbo packet settings, changes to autonegotiation settings, and startup messages.

Driver messages are issued for the following:

• Initialization failures:

  Failed to enable interrupts
  Failed during map register allocation
  Failed to enable interrupts
  Failed to read MAC address

• LAN_FLAGS SYSGEN parameter changes:

  Auto-negotiation disabled per SYSGEN parameter LAN_FLAGS <bit 5>
  Auto-negotiation enabled per SYSGEN parameter LAN_FLAGS <bit 5>
  Jumbo frames enabled per SYSGEN parameter LAN_FLAGS <bit 6>
  Jumbo frames disabled per SYSGEN parameter LAN_FLAGS <bit 6>
  Flow control changed per SYSGEN parameter LAN_FLAGS <bit 7>
  Flow control change disallowed---full-duplex mode required
  Flow control enabled per SYSGEN parameter LAN_FLAGS <bit 7>
  Flow control disabled per SYSGEN parameter LAN_FLAGS <bit 7>

• LANCP speed, duplex mode, auto-negotiation, and flow control changes:

  Link set to speed, duplex, flow control setting
  Link set to auto-negotiate speed, duplex, flow control setting

• Driver detected link state change:

  Link state change---link up: speed, duplex, flow control setting
  Link state change---link down

The driver allows some device-specific parameters to be adjusted. These adjustments are useful for debug purposes or for performance tuning.

You specify device specific functions by using the following LANCP command:

LANCP> SET DEVICE/DEVICE_SPECIFIC=(FUNCTION="func", VALUE=n) EWc

Like other LANCP commands which affect a device, this command requires the SYSPRV privilege.

Table 9-25 lists and describes the device-specific LANCP commands.

Table 9-25 LANCP Device-Specific Commands

Command	Meaning
FUNCTION="CCOU"	Clears all device and driver counters. The value, if supplied, is ignored.
FUNCTION="DXMT", VALUE=n	Changes the transmit delay value, which is the number of microseconds after completion of a transmit request that an interrupt is generated. The current setting is displayed in the internal counters. This function is applicable to Gigabit Ethernet NICs.
FUNCTION="DRCV", VALUE=n	Changes the receive delay value, which is the number of microseconds after completion of a receive that an interrupt is generated. The current setting is displayed in the internal counters. This function is applicable to Gigabit Ethernet NICs.
FUNCTION="CXMT",VALUE=n	Changes the transmit coalesce value, which is the number of transmit buffer descriptors that are processed before an interrupt is generated. An interrupt may be generated earlier if the transmit delay threshold is reached or when an interrupt on behalf of receive or a link state change is generated. The current setting is displayed in the internal counters. This function is applicable to Gigabit Ethernet NICs.
FUNCTION="CRCV", VALUE=n	Changes the receive coalesce value, which is the number of receive buffer descriptors that are filled in before an interrupt is generated. An interrupt may be generated earlier if the receive delay threshold is reached or when an interrupt on behalf of transmit or a link state change is generated. The current setting is displayed in the internal counters. This function is applicable to Gigabit Ethernet NICs.

9.8 FDDI LAN Devices

The PDQ chip is used for a series of FDDI NICs, paired with a different bus interface to cover all of the Alpha I/O buses. Table 9-26 lists the buses, devices, and drivers.

Table 9-26 PDQ FDDI NICs

Bus	Device	Driver
TurboChannel	DEFTA	SYS$FCDRIVER,EXE
FutureBus+	DEFFA	SYS$FADRIVER.EXE
EISA	DEFEA	SYS$FRDRIVER.EXE
PCI	DEFPA	SYS$FWDRIVER.EXE

9.9 TMS380 Token LAN Devices

The TMS380 chip is used for a series of Token Ring NICs, paired with a different bus interface to cover all of the Alpha I/O buses. Table 9-27 lists the buses, devices, and drivers.

Table 9-27 TMS380 Token Ring NICs

Bus	Device	Driver
TurboChannel	DETRA	SYS$ICDRIVER.EXE
EISA	DW300	SYS$IRDRIVER.EXE
ISA	DW110 (P1392+)	SYS$IRDRIVER.EXE
PCI	Racore	SYS$IWDRIVER.EXE
PCI	TC4048	SYS$IWDRIVER.EXE

9.10 LAN ATM Network Support

Asynchronous transfer mode (ATM) is a cell-oriented switching technology that uses fixed-length packets to carry different types of data.

The ATM protocol communicates by first establishing endpoints between two computers with a virtual circuit (VC) through one or more ATM switches. ATM then provides a physical path for data flow between the endpoints by either a permanent virtual circuit (PVC), or a switched virtual circuit (SVC).

Permanent Virtual Circuits (PVCs)

Permanent Virtual Circuits are set up and torn down by prior arrangement. They are established manually by a user before the sending of any data between endpoints on a network. Some PVCs are defined directly on the switch; others are predefined for use in managing switched virtual circuits (SVCs).

Switched Virtual Circuits (SVC)

Switched virtual circuits require no operator interaction to create and manage connections between endpoints. Software sets up and tears down connections dynamically as they are needed through the request of an endpoint.

OpenVMS has deployed ATM networks based on the ATM LANE standards and Classical IP over ATM (RFC 1577). The following ATM adapters on Alpha systems are supported by OpenVMS with the ATM LANE standards:

DGLTA
DGLPB
DGLPA
DAPBA
DAPCA

The following ATM adapters on Alpha systems are supported by OpenVMS with Classical IP over ATM (RFC 1577):

DGLTA
DBLPB
DGLPA

LAN emulation over an ATM network allows existing applications to run essentially unchanged while also allowing the applications to run on computers directly connected to the ATM network. The LAN emulation hides the underlying ATM network at the media access control (MAC) layer, which provides device driver interfaces.

Table 9-28 shows the four components that make up a LAN emulation over ATM network. Of the four components, OpenVMS supports only the LAN emulation client (LEC).

Table 9-28 Components of LAN Emulation over ATM Network

Component	Function
LAN emulation client (LEC)	Provides a software driver that runs on a network client and enables LAN clients to connect to an ATM network.
LAN emulation server (LES)	Maintains a mapping between LAN and ATM addresses by resolving LAN media access control (MAC) addresses with ATM addresses.
Broadcast and Unknown Server (BUS)	Maintains connections with every LAN emulation client (LEC) in the network. For broadcast messages, the BUS sends messages to every attached LEC. The LECs then forward the message to their respectively attached LANs. For multicast messages, the BUS sends messages to only those LECs that have devices in the multicast group. For a LEC that wants to send a regular message whose destination MAC address is unknown, the BUS can be used to determine this address.
LAN emulation Configuration Server (LECS)	Provides a service for LAN emulation clients by helping to determine which emulated LAN each of the LEC's registered users should join, since each client can specify which emulated LAN to join.

The LEC exists on all ATM-attached computers that participate in the LAN emulation configuration. LEC provides the ATM MAC-layer connectionless function that is transparent to the LAN-type applications. The LEC, LES, and BUS can exist on one ATM-attached computer or on separate computers. The server functions usually reside inside an ATM switch, but can be implemented on client systems.

9.10.2 LAN Emulation Topology

Figure 9-1 shows the topology of a typical emulated LAN over ATM.

Figure 9-1 Emulated LAN Topology

Classical IP (CLIP) implements a data-link level device that has the same semantics as an Ethernet interface (802.3). This interface is used by a TCP/IP protocol to transmit 802.3 (IEEE Ethernet) frames over an ATM network. The model that OpenVMS Alpha follows for exchanging IP datagrams over ATM is based on RFC 1577 (Classical IP over ATM).

For information on using LANCP commands to manage Classical IP, refer to the OpenVMS System Management Utilities Reference Manual: A--L.

9.11 Supporting and Configuring LAN Emulation over ATM

OpenVMS provides LAN Emulation Client (LEC) support over ATM. The LAN Emulation Client software supports IEEE/802.3 Emulated LANs, and UNI 3.0 or UNI 3.1 and the following maximum frame size (in bytes): 1516, 4544, and 9234.

The DAPBA (155 Mb/s) and the DAPCA (622 Mb/s) are ATM adapters for PCI-bus systems that are supported by SYS$HWDRIVER4.EXE. The following requirement applies to the DAPBA and DAPCA adapters:

Both adapters require a great deal of non-paged pool, and therefore, care should be taken when configuring them. For each DAPBA, Compaq recommends increasing the SYSGEN parameter NPAGEVIR by 3000000. For each DAPCA, Compaq recommends increasing NPAGEVIR by 6000000. To do this, add the ADD_NPAGEVIR parameter to MODPARAMS.DAT and then run AUTOGEN. For example, add the following command to MODPARAMS.DAT on a system with two DAPBAs and one DAPCA:

ADD_NPAGEVIR = 12000000

The following restrictions apply to the DAPBA and DAPCA adapters:

The adapter cannot be located on a PCI bus that is located behind a PCI-to-PCI bridge. Systems that have this configuration are the following:

Digital Personal AlphaWorkstation 600 (MIATA GL)
AlphaStation 1000A (Noritake)
COMPAQ Professional Workstation XP1000 (MONET)
Alphaserver 2000 and 2100 (SABLE)

SYS$LAN_ATM4.EXE provides OpenVMS ATM infrastructure for the DAPBA and DAPCA adapters. SYS$ELDRIVER4.EXE provides the Emulated LAN support for the DAPBA and DAPCA adapters.

The DGLPB (155 Mb/s) is an ATM device for PCI-bus systems that is supported by SYS$HWDRIVER.EXE.

The DGLPA (155 Mb/s) is an ATM device for PCI-bus systems that is supported by SY$ATMWORKS351.EXE.

The DGLTA (155 Mb/s) is an ATM device for TURBOchannel systems with the exception of the DEC 3000-300 that is supported by SYS$HCDRIVER.EXE.

SYS$LAN_ATM.EXE provides the OpenVMS ATM infrastructure for the DGLPB, DGLPA, and DGLTA adapters. SYS$ELDRIVER.EXE provides the Emulated LAN support for the DGLPB, DGLPA, and DGLTA adapters.

The Emulated LAN driver provides the means for communicating over the LAN ATM. The device type for the Emulated LAN device is DT$_EL_ELAN.

The device name for the Emulated LAN is:

ELcu

where c is the controller and u is the unit number (for example, ELA0).

9.11.1 Specifying the User to Network Interface (UNI)

The ATM software is set to autosense the UNI version by default. Setting bit 3 of the system parameter, LAN_FLAGS, to 1 enables UNI 3.0 over all ATM adapters. Setting bit 4 of the system parameter, LAN_FLAGS, to 1 enables UNI 3.1 over all ATM adapters.

9.11.2 Enabling SONET/SDH

The ATM drivers have the capability of operating with either synchronous optical network (SONET) or synchronous digital hierarchy (SDH) framing. Setting bit 0 of the system parameter, LAN_FLAGS, to 1 enables SDH framing. Setting bit 0 of the system parameter, LAN_FLAGS, to 0 enables SONET framing (default). For this to take affect, the system parameter must be specified correctly before the ATM adapter driver is loaded.

9.11.3 Booting

OpenVMS Alpha does not support ATM adapters as boot devices.

9.11.4 Configuring an Emulated LAN (ELAN)

The LANCP utility sets up an Emulated LAN (ELAN). If the ELAN is defined in the permanent database, these settings take affect at boot time. To define the commands in the permanent database for specific adapters, you invoke the DEFINE DEVICE commands. Once these commands define the adapters in the permanent database, the ELAN can be started during system startup.

You can also invoke the LANCP SET commands to start up an ELAN after the system is booted.

The following example shows the DEFINE DEVICE commands that define the adapter in the permanent database.

$ mcr lancp LANCP> define device ela0/elan=create LANCP> define device ela0/elan=(parent=hwa0,type=csmacd,size=1516) LANCP> define device ela0/elan=(descr="An ATM ELAN") LANCP> define device ela0/elan=enable=startup LANCP> list dev ela0/param Device Characteristics, Permanent Database, for ELA0: Value Characteristic ----- -------------- HWA0 Parent ATM device "An ATM ELAN" Emulated LAN description 1516 Emulated LAN packet size CSMA/CD Emulated LAN type Yes Emulated LAN enabled for startup LANCP> exit $

The following example shows the SET DEVICE commands required for setting up an ELAN with the desired parameters. Note that some of the commands generate a console message.

$ mcr lancp LANCP> set dev ela0/elan=create %%%%%%%%%%% OPCOM 26-MAR-2001 16:57:12.89 %%%%%%%%%%% Message from user SYSTEM on ALPHA1 LANACP LAN Services Found LAN device ELA0, hardware address 00-00-00-00-00-00 LANCP> set dev ela0/elan=(parent=hwa0,type=csmacd,size=1516) LANCP> set dev ela0/elan=(descr="An ATM ELAN") LANCP> set dev ela0/elan=enable=startup %ELDRIVER, LAN Emulation event at 26-MAR-1996 16:57:28.78 %ELDRIVER, LAN Emulation startup: Emulated LAN 1 on device ELA0 LANCP> sho dev ela/char Device Characteristics ELA0: Value Characteristic ----- -------------- Normal Controller mode External Internal loopback mode CSMA/CD Communication medium 16 Minimum receive buffers 32 Maximum receive buffers No Full duplex enable No Full duplex operational Unspecified Line media 10 Line speed (megabits/second) CSMA/CD Communication medium "HWA0" Parent ATM Device "An ATM ELAN" Emulated LAN Description 3999990000000008002B LAN Emulation Server ATM Address A57E80AA000302FF1300 Enabled Emulated LAN State LANCP> exit $

For information about using LANCP and system manager commands with qualifiers for LAN emulation over ATM networks, refer to the OpenVMS System Management Utilities Reference Manual: A--L, and OpenVMS System Manager's Manual.

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