0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 =====================================================
0004 Notes on the DEC FDDIcontroller 700 (DEFZA-xx) driver
0005 =====================================================
0006
0007 :Version: v.1.1.4
0008
0009
0010 DEC FDDIcontroller 700 is DEC's first-generation TURBOchannel FDDI
0011 network card, designed in 1990 specifically for the DECstation 5000
0012 model 200 workstation. The board is a single attachment station and
0013 it was manufactured in two variations, both of which are supported.
0014
0015 First is the SAS MMF DEFZA-AA option, the original design implementing
0016 the standard MMF-PMD, however with a pair of ST connectors rather than
0017 the usual MIC connector. The other one is the SAS ThinWire/STP DEFZA-CA
0018 option, denoted 700-C, with the network medium selectable by a switch
0019 between the DEC proprietary ThinWire-PMD using a BNC connector and the
0020 standard STP-PMD using a DE-9F connector. This option can interface to
0021 a DECconcentrator 500 device and, in the case of the STP-PMD, also other
0022 FDDI equipment and was designed to make it easier to transition from
0023 existing IEEE 802.3 10BASE2 Ethernet and IEEE 802.5 Token Ring networks
0024 by providing means to reuse existing cabling.
0025
0026 This driver handles any number of cards installed in a single system.
0027 They get fddi0, fddi1, etc. interface names assigned in the order of
0028 increasing TURBOchannel slot numbers.
0029
0030 The board only supports DMA on the receive side. Transmission involves
0031 the use of PIO. As a result under a heavy transmission load there will
0032 be a significant impact on system performance.
0033
0034 The board supports a 64-entry CAM for matching destination addresses.
0035 Two entries are preoccupied by the Directed Beacon and Ring Purger
0036 multicast addresses and the rest is used as a multicast filter. An
0037 all-multi mode is also supported for LLC frames and it is used if
0038 requested explicitly or if the CAM overflows. The promiscuous mode
0039 supports separate enables for LLC and SMT frames, but this driver
0040 doesn't support changing them individually.
0041
0042
0043 Known problems:
0044
0045 None.
0046
0047
0048 To do:
0049
0050 5. MAC address change. The card does not support changing the Media
0051 Access Controller's address registers but a similar effect can be
0052 achieved by adding an alias to the CAM. There is no way to disable
0053 matching against the original address though.
0054
0055 7. Queueing incoming/outgoing SMT frames in the driver if the SMT
0056 receive/RMC transmit ring is full. (?)
0057
0058 8. Retrieving/reporting FDDI/SNMP stats.
0059
0060
0061 Both success and failure reports are welcome.
0062
0063 Maciej W. Rozycki <macro@orcam.me.uk>
