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diff --git a/Documentation/networking/decnet.txt b/Documentation/networking/decnet.txt new file mode 100644 index 000000000000..c6bd25f5d61d --- /dev/null +++ b/Documentation/networking/decnet.txt @@ -0,0 +1,234 @@ + 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> + |