-----------------------------------------------------------------------------
1) This file is a supplement to arcnet.txt. Please read that for general
driver configuration help.
-----------------------------------------------------------------------------
2) This file is no longer Linux-specific. It should probably be moved out of
the kernel sources. Ideas?
-----------------------------------------------------------------------------
Because so many people (myself included) seem to have obtained ARCnet cards
without manuals, this file contains a quick introduction to ARCnet hardware,
some cabling tips, and a listing of all jumper settings I can find. Please
e-mail apenwarr@worldvisions.ca with any settings for your particular card,
or any other information you have!
INTRODUCTION TO ARCNET
----------------------
ARCnet is a network type which works in a way similar to popular Ethernet
networks but which is also different in some very important ways.
First of all, you can get ARCnet cards in at least two speeds: 2.5 Mbps
(slower than Ethernet) and 100 Mbps (faster than normal Ethernet). In fact,
there are others as well, but these are less common. The different hardware
types, as far as I'm aware, are not compatible and so you cannot wire a
100 Mbps card to a 2.5 Mbps card, and so on. From what I hear, my driver does
work with 100 Mbps cards, but I haven't been able to verify this myself,
since I only have the 2.5 Mbps variety. It is probably not going to saturate
your 100 Mbps card. Stop complaining. :)
You also cannot connect an ARCnet card to any kind of Ethernet card and
expect it to work.
There are two "types" of ARCnet - STAR topology and BUS topology. This
refers to how the cards are meant to be wired together. According to most
available documentation, you can only connect STAR cards to STAR cards and
BUS cards to BUS cards. That makes sense, right? Well, it's not quite
true; see below under "Cabling."
Once you get past these little stumbling blocks, ARCnet is actually quite a
well-designed standard. It uses something called "modified token passing"
which makes it completely incompatible with so-called "Token Ring" cards,
but which makes transfers much more reliable than Ethernet does. In fact,
ARCnet will guarantee that a packet arrives safely at the destination, and
even if it can't possibly be delivered properly (ie. because of a cable
break, or because the destination computer does not exist) it will at least
tell the sender about it.
Because of the carefully defined action of the "token", it will always make
a pass around the "ring" within a maximum length of time. This makes it
useful for realtime networks.
In addition, all known ARCnet cards have an (almost) identical programming
interface. This means that with one ARCnet driver you can support any
card, whereas with Ethernet each manufacturer uses what is sometimes a
completely different programming interface, leading to a lot of different,
sometimes very similar, Ethernet drivers. Of course, always using the same
programming interface also means that when high-performance hardware
facilities like PCI bus mastering DMA appear, it's hard to take advantage of
them. Let's not go into that.
One thing that makes ARCnet cards difficult to program for, however, is the
limit on their packet sizes; standard ARCnet can only send packets that are
up to 508 bytes in length. This is smaller than the Internet "bare minimum"
of 576 bytes, let alone the Ethernet MTU of 1500. To compensate, an extra
level of encapsulation is defined by RFC1201, which I call "packet
splitting," that allows "virtual packets" to grow as large as 64K each,
although they are generally kept down to the Ethernet-style 1500 bytes.
For more information on the advantages and disadvantages (mostly the
advantages) of ARCnet networks, you might try the "ARCnet Trade Association"
WWW page:
http://www.arcnet.com
CABLING ARCNET NETWORKS
-----------------------
This section was rewritten by
Vojtech Pavlik <vojtech@suse.cz>
using information from several people, including:
Avery Pennraun <apenwarr@worldvisions.ca>
Stephen A. Wood <saw@hallc1.cebaf.gov>
John Paul Morrison <jmorriso@bogomips.ee.ubc.ca>
Joachim Koenig <jojo@repas.de>
and Avery touched it up a bit, at Vojtech's request.
ARCnet (the classic 2.5 Mbps version) can be connected by two different
types of cabling: coax and twisted pair. The other ARCnet-type networks
(100 Mbps TCNS and 320 kbps - 32 Mbps ARCnet Plus) use different types of
cabling (Type1, Fiber, C1, C4, C5).
For a coax network, you "should" use 93 Ohm RG-62 cable. But other cables
also work fine, because ARCnet is a very stable network. I personally use 75
Ohm TV antenna cable.
Cards for coax cabling are shipped in two different variants: for BUS and
STAR network topologies. They are mostly the same. The only difference
lies in the hybrid chip installed. BUS cards use high impedance output,
while STAR use low impedance. Low impedance card (STAR) is electrically
equal to a high impedance one with a terminator installed.
Usually, the ARCnet networks are built up from STAR cards and hubs. There
are two types of hubs - active and passive. Passive hubs are small boxes
with four BNC connectors containing four 47 Ohm resistors:
| | wires
R + junction
-R-+-R- R 47 Ohm resistors
R
|
The shielding is connected together. Active hubs are much more complicated;
they are powered and contain electronics to amplify the signal and send it
to other segments of the net. They usually have eight connectors. Active
hubs come in two variants - dumb and smart. The dumb variant just
amplifies, but the smart one decodes to digital and encodes back all packets
coming through. This is much better if you have several hubs in the net,
since many dumb active hubs may worsen the signal quality.
And now to the cabling. What you can connect together:
1. A card to a card. This is the simplest way of creating a 2-computer
network.
2. A card to a passive hub. Remember that all unused connectors on the hub
must be properly terminated with 93 Ohm (or something else if you don't
have the right ones) terminators.
(Avery's note: oops, I didn't know that. Mine (TV cable) works
anyway, though.)
3. A card to an active hub. Here is no need to terminate the unused
connectors except some kind of aesthetic feeling. But, there may not be
more than eleven active hubs between any two computers. That of course
doesn't limit the number of active hubs on the network.
4. An active hub to another.
5. An active hub to passive hub.
Remember, that you can not connect two passive hubs together. The power loss
implied by such a connection is too high for the net to operate reliably.
An example of a typical ARCnet network:
R S - STAR type card
S------H--------A-------S R - Terminator
| | H - Hub
| | A - Active hub
| S----H----S
S |
|
S
The BUS topology is very similar to the one used by Ethernet. The only
difference is in cable and terminators: they should be 93 Ohm. Ethernet
uses 50 Ohm impedance. You use T connectors to put the computers on a single
line of cable, the bus. You have to put terminators at both ends of the
cable. A typical BUS ARCnet network looks like:
RT----T------T------T------T------TR
B B B B B B
B - BUS type card
R - Terminator
T - T connector
But that is not all! The two ty
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nls_cp949.c 854KB
advansys.c 724KB
nls_cp936.c 677KB
qlogicfc_asm.c 618KB
nls_cp950.c 580KB
nls_cp932.c 478KB
aic7xxx_old.c 392KB
init301.c 389KB
sym53c8xx.c 368KB
dgrs_firmware.c 351KB
ixj.c 316KB
FlashPoint.c 308KB
ips.c 278KB
aic79xx_core.c 258KB
DAC960.c 257KB
synclink.c 232KB
ncr53c8xx.c 225KB
pcibr.c 220KB
skgepnmi.c 220KB
ide-tape.c 217KB
qla1280.c 217KB
mptscsih.c 210KB
53c7,8xx.c 202KB
s390io.c 198KB
tg3.c 197KB
init.c 191KB
smctr.c 191KB
53c7xx.c 190KB
aic7xxx_core.c 189KB
cyclades.c 186KB
cpqfcTSworker.c 185KB
aironet4500_rid.c 183KB
font_sun12x22.c 182KB
BusLogic.c 180KB
de4x5.c 174KB
osst.c 172KB
serial.c 170KB
airo.c 169KB
ov511.c 169KB
ov511.c 169KB
gdth.c 167KB
mptbase.c 165KB
sbpcd.c 164KB
cs46xx.c 160KB
e1000_hw.c 158KB
awe_wave.c 154KB
pcibr_dvr.c 154KB
ioctl32.c 151KB
sdla_x25.c 151KB
sdla_fr.c 148KB
synclinkmp.c 147KB
iph5526.c 147KB
sym_hipd.c 146KB
megaraid.c 141KB
aic79xx_osm.c 141KB
istallion.c 141KB
wavelan_cs.c 137KB
stallion.c 136KB
ioctl32.c 135KB
cs4281m.c 132KB
dasd.c 131KB
agpgart_be.c 131KB
ia32_ioctl.c 130KB
skge.c 130KB
sdla_chdlc.c 129KB
qlogicisp_asm.c 128KB
sys_ppc32.c 126KB
audio.c 126KB
audio.c 126KB
sis_main.c 126KB
3w-xxxx.c 125KB
perfmon.c 122KB
smc91111.c 122KB
ibmcam.c 120KB
ibmcam.c 120KB
esp.c 120KB
zr36067.c 119KB
trident.c 118KB
wavelan.c 118KB
synclink_cs.c 118KB
base.c 116KB
ppc-opc.c 115KB
ppc-opc.c 115KB
jfs_dmap.c 115KB
softfloat.c 115KB
sys_ia32.c 115KB
ip2main.c 114KB
e100_main.c 114KB
epca.c 114KB
floppy.c 113KB
skxmac2.c 113KB
sys_sparc32.c 113KB
hostap_ioctl.c 112KB
st.c 112KB
tcp_input.c 112KB
orinoco.c 111KB
ali5455.c 111KB
iphase.c 111KB
linux32.c 110KB
ioctl32.c 110KB
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