Frequently Asked Questions: ARCNET & Linux


  1. 1. Can I use your ARCNET cards with Linux ?
  2. 2. Where can I find out more about the ARCNET Linux driver?

Can I use your ARCNET cards with Linux ?

The Linux 2.4.0 Kernel, released January 4, 2001, adds PCMCIA and PCI to its ARCNET functionality. This Kernel also offers improved stability for multiprocessor systems and for non-Intel platforms.

Hosts using incompatible Internet standards can talk to each other since Linux automatically routes RFC1051 and RFC1201 packets — allowing them to coexist on one network.

RFC1051 messages cannot exceed one packet in size, but RFC1201 messages can span multiple packets.  Each message type uses a unique system code.   RFC1201 is the basis of the ARCNET Trade Association's ATA878.2 standard that concerns generic fragmentation.

Linux-ARCNET works by employing three modules in one driver to provide:

  • a basic ARCNET driver
  • a protocol driver
  • a driver for a specific controller chip

The first module provides the basic ability to exchange raw ARCNET packets.  The second module encapsulates packets in some protocol — such as TCP/IP. The third module allows communication with a given controller.

The Contemporary Controls PCI and PCMCIA series of adapters, use the COM20020 controller chip.  The PCI20 adapters are autodetected in Linux with the com20020pci driver while the PCM20 units use the com20020pcm driver.

Inserting a PCM20 into a PCMCIA slot, causes the arc0 device to be created. When the card is removed, the arc0 device should disappear.

A common user error with Kernel 2.4 is overlooking the fact that the protocol driver must be loaded separately.  To do this, execute insmod rfc1201.

Note: The above features are also available by upgrading a Linux 2.2 ARCNET driver to the latest "beta" version.

More information about Linux support for ARCNET is available in the technotes section

Where can I find out more about the ARCNET Linux driver?