Document revision date: 30 March 2001

CSMA/CD drivers support the following features:

• Ethernet and IEEE 802.3 packet format
• Physical layer identified as type 10Base5 (10-Mbps baseband (ThickWire)), 10Base2 (ThinWire), and 10BaseT (twisted pair)
• Fast Ethernet and IEEE 802.3u packet format
• Fast Ethernet physical layer identified as type 100BaseT
• Gigabit Ethernet and IEEE 802.3z packet format
• Gigabit Ethernet's physical layer is identified as type 1000BaseT for unshielded twisted pair (UTP), category 5, 1000Base-SX for multimode fiber-optic cables.

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 commands and responses (XID) and TEST commands, and the XID and TEST 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
  The IEEE 802.3 Standard states that the size of the destination and source addresses be 2 or 6 bytes, as decided by the manufacturer. The OpenVMS LAN drivers and controllers only support 6-byte 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)

System software and user applications communicate with other systems through the LAN controllers using the QIO interface defined by the OpenVMS LAN driver software. The description of this interface is described later in this chapter. The LAN driver software allows communication with these differing 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 LANs (Alpha Only)

Fast Ethernet (802.3u) is an extension of the IEEE 802.3 standard. It typically runs over twisted-pair wiring (100BaseT). It increases the data transmission rate from 10 to 100Mbps and decreases the maximum length of a network segment. Fast Ethernet controllers allow either 10 or 100Mbps operation for compatibility with existing 10Mbps controllers on the same network segment. The DE500-FA Fast Ethernet controller provides a fiber-optic connection (100BaseFX).

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 standards. It provides full-duplex performance with network servers, using only two of the four pairs of wires.
100BaseT4	Works with twisted-pair cabling standards. It uses four pairs of wiring with one pair for transmission, another for reception, and two pairs that can be used to either transmit or receive data. It does not support full-duplex operations.
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.

The OpenVMS operating system supports the following Fast Ethernet adapters on Alpha PCI-based systems:

DE500-XA
DE500-AA
DE500-BA
DE500-FA

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 1000Mbps. 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 Mbps operation for compatibility with existing 10 or 100 Mbps controllers on the same network seqment.

Table 9-4 shows the types of cabling used for Gigabit Ethernet.

Table 9-4 Gigabit Ethernet Cabling

Cable	Description
1000Base-SX	Works with fiber optic cabling. Used mainly for shorter backbone applications. With multimode, it supports distances of up to 550 meters.
1000Base-LX	Works with fiber optic cabling. Used mainly for longer single-mode building of fiber backbones and single-mode campus backbones. With single mode, it supports distances of up to 5 kilometers.
1000Base-CX	Works with shielded copper cabling. Used mainly for interconnection of equipment clusters where the physical interface is short. It supports, for example, a switching closet or computer room with interconnections to 25-meter distances.
1000BaseT	Works with unshielded copper cabling. Used mainly for horizontal copper cabling 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 LAN ATM Network Support (Alpha Only)

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 9-5 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 9-5 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.

9.6.2 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.

9.7 Supporting and Configuring LAN Emulation over ATM (Alpha Only)

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 M/bs) is an ATM device for PCI-bus systems that is supported by SYS$HWDRIVER.EXE.

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

The DGLTA (155 M/bs) 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).

9.7.1 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.

9.7.2 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.

9.7.3 Booting

OpenVMS Alpha does not support ATM adapters as boot devices.

9.7.4 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.

9.8 Ports and LAN Configuration

A port in a LAN configuration consists of a protocol type, a service access point (SAP) or protocol identifier, and a controller. There are as many ports on a LAN controller as there are protocol types, SAPs, and protocol identifiers. Each port is independent of other ports running on the same LAN controller.

Application programs use either the LAN driver's QIO interface or VCI interface to perform I/O operations to and from other nodes on the LAN. This chapter describes the QIO interface. Figure 9-2 shows the relationship of most Ethernet controllers to the processor and to the user application program.

Figure 9-2 Typical Ethernet Configuration

The following sequence initializes and starts a port on a LAN device driver:

1. Use the Assign I/O Channel ($ASSIGN) system service to assign I/O channels to one or more of the LAN device names and devices specified in Table 9-1 and Table 9-2. $ASSIGN creates a new unit control block (UCB), to which the channel for the port is assigned.
2. Start up the port with the set mode function and startup function modifier (see Section 9.16.3.1). You must supply the required P2 buffer parameters listed in Table 9-16.
3. Perform read, write, and sense mode operations as needed.
4. Shut down the port with the set mode function and shutdown function modifier (see Section 9.16.3.4).
5. Use the Deassign I/O Channel ($DASSGN) system service to deassign the I/O channel.

The sample programs described in Section 9.18.2 illustrate how to perform these procedures for Ethernet and IEEE 802 ports.

9.9 Ethernet Addresses

The LAN is a medium for creating a network; it is not a network by itself. The LAN controller and the local system constitute a node. Nodes on the LAN are identified by unique Ethernet addresses. A message can be sent to one, several, or all nodes on the LAN simultaneously, depending on the Ethernet address used. You do not have to specify the Ethernet address of your own node to communicate with other nodes on the same Ethernet. However, you do need to know the Ethernet address of the node with which you want to communicate.

9.9.1 Format of Ethernet Addresses

An Ethernet address is 48 bits in length. Ethernet addresses are represented by the Ethernet standard as six pairs of hexadecimal digits (six bytes), separated by hyphens (for example, AA-01-23-45-67-FF). The bytes are displayed from left to right in the order in which they are transmitted; bits within each byte are transmitted from right to left. In this example, byte AA is transmitted first; byte FF is transmitted last. (See the description of NMA$C_PCLI_PHA in Table 9-16, Section 9.16.3.1, for the internal representation of addresses.)

Upon application, IEEE assigns a block of addresses to a producer of LAN nodes. Thus, every manufacturer has a unique set of addresses to use. Normally, one address out of the assigned block of physical addresses is permanently associated with each controller (usually in read-only memory). This address is known as the hardware address of the controller. Each individual controller has a unique hardware address.

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