Supported Networks

Digital UNIX Version 4.0 supports interfacing to the following networks:

• ATM

• Ethernet

• Fast Ethernet

• FDDI

• Token Ring

ATM

Digital UNIX Version 4.0 supports PCI and TURBOchannel machines on 155.5 MB per second Asynchronous Transfer Mode (ATM) networks. ATM is a high-speed, connection-based, cell-switched network that−−unlike traditional packet switched networks−−can carry different kinds of traffic (voice, video, and data) simultaneously. In addition, ATM provides predictable services to those classes of traffic that require bounded latencies and dedicated bandwidths, and−−because ATM separates the physical interface from the datalink layer−−the same cell and packet formats can be used over a wide variety of physical interfaces from 1 MB per second to 10 GB per second.

Digital UNIX Version 4.0's implementation of ATM consists of permanent virtual circuit support; switched virtual circuit support through ATM Forum UNI 3.0 and 3.1 signalling for point-to-point connections; Classic IP (as defined by RFC 1577, RFC 1483, and RFC 1626) for a single Logical IP Subnet (LIS); and ATM Forum Interim Local Management Interface (ILMI) for dynamic network address registration. For more information on ATM, see the Network Programmer's Guide.

Ethernet

Digital UNIX Version 4.0 supports 10 MB per second Ethernet networks on all Alpha platforms.

At the physical and IP levels, Digital UNIX Version 4.0 supports an Ethernet network with a Maximum Transfer Unit (MTU) of 1500 bytes at a maximum of 10 MB per second.

In conformance with Ethernet standards, Digital UNIX Version 4.0 always ensures a minimum packet size of 60 bytes.

The default MTU at the IP level is 1500 bytes at a maximum of 10 MB per second, although this value can be decreased using the ifconfig command.

Fast Ethernet

Digital UNIX Version 4.0 supports 100 MB per second Fast Ethernet (IEEE 802.3 100Base-TX) networks on all PCI-based Alpha hardware platforms.

MTU sizes at the physical and IP levels are the same as those for regular 10 MB per second Ethernet.

FDDI

Digital UNIX Version 4.0 supports 100 MB per second FDDI networks in conformance with RFC 1042 and RFC 1188 on all Alpha hardware platforms.

At the physical level, Digital UNIX Version 4.0 supports an FDDI network with a Maximum Transfer Unit (MTU) of 4500 bytes at a maximum of 100 MB per second. At the IP level, the MTU is 4352 bytes at a maximum of 100 MB per second.

The default MTU at the IP level is always 4352 bytes at a maximum of 100 MB per second, although this value can be decreased using the ifconfig command.

Token Ring

Digital UNIX Version 4.0 supports 4 MB per second and 16 MB per second Token Ring networks and source routing in conformance with RFC 1042 on TURBOchannel, ISA, EISA, and PCI-based Alpha hardware platforms.

Support for Token Ring networks extends networking support to the PC community, since most PC networks are Token Ring and most PCs do not have Ethernet or FDDI adapters.

At the physical level, Digital UNIX Version 4.0 supports a Token Ring network with a Maximum Transfer Unit (MTU) of 4472 bytes at a maximum of 4 MB per second and 17800 bytes at a maximum of 16 MB per second. At the IP level, the MTU is 4092 bytes at a maximum of 4 MB per second and 8188 bytes at a maximum of 16 MB per second.

The default MTU at the IP level is always 4092 for both 4 and 16 MB per second, although this value can be increased or decreased using the ifconfig command.