1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
235 lines
11 KiB
Plaintext
235 lines
11 KiB
Plaintext
Linux DECnet Networking Layer Information
|
|
===========================================
|
|
|
|
1) Other documentation....
|
|
|
|
o Project Home Pages
|
|
http://www.chygwyn.com/DECnet/ - Kernel info
|
|
http://linux-decnet.sourceforge.net/ - Userland tools
|
|
http://www.sourceforge.net/projects/linux-decnet/ - Status page
|
|
|
|
2) Configuring the kernel
|
|
|
|
Be sure to turn on the following options:
|
|
|
|
CONFIG_DECNET (obviously)
|
|
CONFIG_PROC_FS (to see what's going on)
|
|
CONFIG_SYSCTL (for easy configuration)
|
|
|
|
if you want to try out router support (not properly debugged yet)
|
|
you'll need the following options as well...
|
|
|
|
CONFIG_DECNET_ROUTER (to be able to add/delete routes)
|
|
CONFIG_NETFILTER (will be required for the DECnet routing daemon)
|
|
|
|
CONFIG_DECNET_ROUTE_FWMARK is optional
|
|
|
|
Don't turn on SIOCGIFCONF support for DECnet unless you are really sure
|
|
that you need it, in general you won't and it can cause ifconfig to
|
|
malfunction.
|
|
|
|
Run time configuration has changed slightly from the 2.4 system. If you
|
|
want to configure an endnode, then the simplified procedure is as follows:
|
|
|
|
o Set the MAC address on your ethernet card before starting _any_ other
|
|
network protocols.
|
|
|
|
As soon as your network card is brought into the UP state, DECnet should
|
|
start working. If you need something more complicated or are unsure how
|
|
to set the MAC address, see the next section. Also all configurations which
|
|
worked with 2.4 will work under 2.5 with no change.
|
|
|
|
3) Command line options
|
|
|
|
You can set a DECnet address on the kernel command line for compatibility
|
|
with the 2.4 configuration procedure, but in general it's not needed any more.
|
|
If you do st a DECnet address on the command line, it has only one purpose
|
|
which is that its added to the addresses on the loopback device.
|
|
|
|
With 2.4 kernels, DECnet would only recognise addresses as local if they
|
|
were added to the loopback device. In 2.5, any local interface address
|
|
can be used to loop back to the local machine. Of course this does not
|
|
prevent you adding further addresses to the loopback device if you
|
|
want to.
|
|
|
|
N.B. Since the address list of an interface determines the addresses for
|
|
which "hello" messages are sent, if you don't set an address on the loopback
|
|
interface then you won't see any entries in /proc/net/neigh for the local
|
|
host until such time as you start a connection. This doesn't affect the
|
|
operation of the local communications in any other way though.
|
|
|
|
The kernel command line takes options looking like the following:
|
|
|
|
decnet=1,2
|
|
|
|
the two numbers are the node address 1,2 = 1.2 For 2.2.xx kernels
|
|
and early 2.3.xx kernels, you must use a comma when specifying the
|
|
DECnet address like this. For more recent 2.3.xx kernels, you may
|
|
use almost any character except space, although a `.` would be the most
|
|
obvious choice :-)
|
|
|
|
There used to be a third number specifying the node type. This option
|
|
has gone away in favour of a per interface node type. This is now set
|
|
using /proc/sys/net/decnet/conf/<dev>/forwarding. This file can be
|
|
set with a single digit, 0=EndNode, 1=L1 Router and 2=L2 Router.
|
|
|
|
There are also equivalent options for modules. The node address can
|
|
also be set through the /proc/sys/net/decnet/ files, as can other system
|
|
parameters.
|
|
|
|
Currently the only supported devices are ethernet and ip_gre. The
|
|
ethernet address of your ethernet card has to be set according to the DECnet
|
|
address of the node in order for it to be autoconfigured (and then appear in
|
|
/proc/net/decnet_dev). There is a utility available at the above
|
|
FTP sites called dn2ethaddr which can compute the correct ethernet
|
|
address to use. The address can be set by ifconfig either before at
|
|
at the time the device is brought up. If you are using RedHat you can
|
|
add the line:
|
|
|
|
MACADDR=AA:00:04:00:03:04
|
|
|
|
or something similar, to /etc/sysconfig/network-scripts/ifcfg-eth0 or
|
|
wherever your network card's configuration lives. Setting the MAC address
|
|
of your ethernet card to an address starting with "hi-ord" will cause a
|
|
DECnet address which matches to be added to the interface (which you can
|
|
verify with iproute2).
|
|
|
|
The default device for routing can be set through the /proc filesystem
|
|
by setting /proc/sys/net/decnet/default_device to the
|
|
device you want DECnet to route packets out of when no specific route
|
|
is available. Usually this will be eth0, for example:
|
|
|
|
echo -n "eth0" >/proc/sys/net/decnet/default_device
|
|
|
|
If you don't set the default device, then it will default to the first
|
|
ethernet card which has been autoconfigured as described above. You can
|
|
confirm that by looking in the default_device file of course.
|
|
|
|
There is a list of what the other files under /proc/sys/net/decnet/ do
|
|
on the kernel patch web site (shown above).
|
|
|
|
4) Run time kernel configuration
|
|
|
|
This is either done through the sysctl/proc interface (see the kernel web
|
|
pages for details on what the various options do) or through the iproute2
|
|
package in the same way as IPv4/6 configuration is performed.
|
|
|
|
Documentation for iproute2 is included with the package, although there is
|
|
as yet no specific section on DECnet, most of the features apply to both
|
|
IP and DECnet, albeit with DECnet addresses instead of IP addresses and
|
|
a reduced functionality.
|
|
|
|
If you want to configure a DECnet router you'll need the iproute2 package
|
|
since its the _only_ way to add and delete routes currently. Eventually
|
|
there will be a routing daemon to send and receive routing messages for
|
|
each interface and update the kernel routing tables accordingly. The
|
|
routing daemon will use netfilter to listen to routing packets, and
|
|
rtnetlink to update the kernels routing tables.
|
|
|
|
The DECnet raw socket layer has been removed since it was there purely
|
|
for use by the routing daemon which will now use netfilter (a much cleaner
|
|
and more generic solution) instead.
|
|
|
|
5) How can I tell if its working ?
|
|
|
|
Here is a quick guide of what to look for in order to know if your DECnet
|
|
kernel subsystem is working.
|
|
|
|
- Is the node address set (see /proc/sys/net/decnet/node_address)
|
|
- Is the node of the correct type
|
|
(see /proc/sys/net/decnet/conf/<dev>/forwarding)
|
|
- Is the Ethernet MAC address of each Ethernet card set to match
|
|
the DECnet address. If in doubt use the dn2ethaddr utility available
|
|
at the ftp archive.
|
|
- If the previous two steps are satisfied, and the Ethernet card is up,
|
|
you should find that it is listed in /proc/net/decnet_dev and also
|
|
that it appears as a directory in /proc/sys/net/decnet/conf/. The
|
|
loopback device (lo) should also appear and is required to communicate
|
|
within a node.
|
|
- If you have any DECnet routers on your network, they should appear
|
|
in /proc/net/decnet_neigh, otherwise this file will only contain the
|
|
entry for the node itself (if it doesn't check to see if lo is up).
|
|
- If you want to send to any node which is not listed in the
|
|
/proc/net/decnet_neigh file, you'll need to set the default device
|
|
to point to an Ethernet card with connection to a router. This is
|
|
again done with the /proc/sys/net/decnet/default_device file.
|
|
- Try starting a simple server and client, like the dnping/dnmirror
|
|
over the loopback interface. With luck they should communicate.
|
|
For this step and those after, you'll need the DECnet library
|
|
which can be obtained from the above ftp sites as well as the
|
|
actual utilities themselves.
|
|
- If this seems to work, then try talking to a node on your local
|
|
network, and see if you can obtain the same results.
|
|
- At this point you are on your own... :-)
|
|
|
|
6) How to send a bug report
|
|
|
|
If you've found a bug and want to report it, then there are several things
|
|
you can do to help me work out exactly what it is that is wrong. Useful
|
|
information (_most_ of which _is_ _essential_) includes:
|
|
|
|
- What kernel version are you running ?
|
|
- What version of the patch are you running ?
|
|
- How far though the above set of tests can you get ?
|
|
- What is in the /proc/decnet* files and /proc/sys/net/decnet/* files ?
|
|
- Which services are you running ?
|
|
- Which client caused the problem ?
|
|
- How much data was being transferred ?
|
|
- Was the network congested ?
|
|
- If there was a kernel panic, please run the output through ksymoops
|
|
before sending it to me, otherwise its _useless_.
|
|
- How can the problem be reproduced ?
|
|
- Can you use tcpdump to get a trace ? (N.B. Most (all?) versions of
|
|
tcpdump don't understand how to dump DECnet properly, so including
|
|
the hex listing of the packet contents is _essential_, usually the -x flag.
|
|
You may also need to increase the length grabbed with the -s flag. The
|
|
-e flag also provides very useful information (ethernet MAC addresses))
|
|
|
|
7) MAC FAQ
|
|
|
|
A quick FAQ on ethernet MAC addresses to explain how Linux and DECnet
|
|
interact and how to get the best performance from your hardware.
|
|
|
|
Ethernet cards are designed to normally only pass received network frames
|
|
to a host computer when they are addressed to it, or to the broadcast address.
|
|
|
|
Linux has an interface which allows the setting of extra addresses for
|
|
an ethernet card to listen to. If the ethernet card supports it, the
|
|
filtering operation will be done in hardware, if not the extra unwanted packets
|
|
received will be discarded by the host computer. In the latter case,
|
|
significant processor time and bus bandwidth can be used up on a busy
|
|
network (see the NAPI documentation for a longer explanation of these
|
|
effects).
|
|
|
|
DECnet makes use of this interface to allow running DECnet on an ethernet
|
|
card which has already been configured using TCP/IP (presumably using the
|
|
built in MAC address of the card, as usual) and/or to allow multiple DECnet
|
|
addresses on each physical interface. If you do this, be aware that if your
|
|
ethernet card doesn't support perfect hashing in its MAC address filter
|
|
then your computer will be doing more work than required. Some cards
|
|
will simply set themselves into promiscuous mode in order to receive
|
|
packets from the DECnet specified addresses. So if you have one of these
|
|
cards its better to set the MAC address of the card as described above
|
|
to gain the best efficiency. Better still is to use a card which supports
|
|
NAPI as well.
|
|
|
|
|
|
8) Mailing list
|
|
|
|
If you are keen to get involved in development, or want to ask questions
|
|
about configuration, or even just report bugs, then there is a mailing
|
|
list that you can join, details are at:
|
|
|
|
http://sourceforge.net/mail/?group_id=4993
|
|
|
|
9) Legal Info
|
|
|
|
The Linux DECnet project team have placed their code under the GPL. The
|
|
software is provided "as is" and without warranty express or implied.
|
|
DECnet is a trademark of Compaq. This software is not a product of
|
|
Compaq. We acknowledge the help of people at Compaq in providing extra
|
|
documentation above and beyond what was previously publicly available.
|
|
|
|
Steve Whitehouse <SteveW@ACM.org>
|
|
|