HOWTO for using RTnet over FireWire (ETH1394)
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=============================================
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To use RTnet over FireWire, one needs another package, i.e. RT-FireWire, which
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can be checked out via "svn checkout svn://svn.berlios.de/rtfirewire/trunk".
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RT-FireWire package is developed by RT-FireWire project team, see the project
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homepage for more interesting information (http://rtfirewire.berlios.de).
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It is recommended to compile and test the RT-FireWire package first.
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RT-FireWire only compiles with fusion. At the time of writing, it is the CVS
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version of fusion which will become release 0.9. Use --with-rtai=XXX to
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specify the installation location of fusion in your system.
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To compile RTnet's Eth1394 driver with RT-FireWire, one needs to do 2 things
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in configuration:
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1. add --with-rtfw=XXX to specify the source location of RT-FireWire
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2. add --enable-eth1394 to enable the compiling of eth1394
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Of course, don't forget --with-rtai=XXX for RTnet.
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RT-FireWire comes with some basic testing tool, one of which is similiar to
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"rtping" on Ethernet. See the Readme of RT-FireWire for how to play around
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with basic FireWire testing.
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Currently, Eth1394 appears exactly the same as normal Ethernet device. So from
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the application point of view, no medium difference can be seen, which means
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application on Ethernet can be directly moved to FireWire without any porting
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effort.
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So, play around with your new medium i.e. FireWire, with exactly the same tool
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on Ethernet-:).
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Modification to RFC2734
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=======================
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Each IP-capable node must have it own unique hardware address in the network.
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The original IPover1394 spec (RFC2734) employs the 64-bit GUID of each
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FireWire adapter chip as the hardware address. That way, the hardware address
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can be guaranteed to be unique even in the world scale, but the address
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resolution process is not efficient, see below:
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ARP Eth1394 internal
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resolution resolution
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48-bit MAC 16-bit
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IP address -----------> (64-bit GUID) ---------------> FireWire nodeid
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The modified ARP on IPover1394 directly use the FireWire node id as hardware
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address for each Eth1394 nodes. That way, the mapping between IP address and
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hardware address (FireWire node id) only needs one time of resolution, which
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is more efficient than the original one. Note that here we assume that we use
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static allocation of 1394 address space to IPover1394, i.e. on each node, the
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address space for Eth1394 would be exactly the same, see "eth1394.h". So, the
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16 bits would be enough to represent the hardware address. Now the address
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resolution process is more efficient, as below:
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ARP resolution
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48-bit IP address ---------------> MAC (FireWire nodeid)
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To give exactly the same look as normal Ethernet devices, the MAC address of
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Eth1394 is extended to 6-bytes by filling 0 after the 2 bytes FireWire node
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id. This way all the highlevel stuff which is already working on Ethernet,
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like RTnet's TDMA, RTcfg, can be directly moved to Eth1394.
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Good Luck!
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2005-08-02 Zhang Yuchen <yuchen623-at-gmail.com>
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