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4. 3c359.txt

3COM PCI TOKEN LINK VELOCITY XL TOKEN RING CARDS README

Release 0.9.0 - Release   
	Jul 17th 2000 Mike Phillips 

	1.2.0 - Final
	Feb 17th 2002 Mike Phillips 
	Updated for submission to the 2.4.x kernel.

Thanks:
	Terry Murphy from 3Com for tech docs and support,
	Adam D. Ligas for testing the driver.
 
Note:
	This driver will NOT work with the 3C339 Token Ring cards, you need
to use the tms380 driver instead.

Options:

The driver accepts three options: ringspeed, pkt_buf_sz and message_level.

These options can be specified differently for each card found. 

ringspeed:  Has one of three settings 0 (default), 4 or 16.  0 will 
make the card autosense the ringspeed and join at the appropriate speed, 
this will be the default option for most people.  4 or 16 allow you to 
explicitly force the card to operate at a certain speed.  The card will fail 
if you try to insert it at the wrong speed. (Although some hubs will allow 
this so be *very* careful).  The main purpose for explicitly setting the ring
speed is for when the card is first on the ring.  In autosense mode, if the card
cannot detect any active monitors on the ring it will open at the same speed as
its last opening. This can be hazardous if this speed does not match the speed
you want the ring to operate at.  

pkt_buf_sz:  This is this initial receive buffer allocation size.  This will
default to 4096 if no value is entered. You may increase performance of the 
driver by setting this to a value larger than the network packet size, although
the driver now re-sizes buffers based on MTU settings as well. 

message_level: Controls level of messages created by the driver. Defaults to 0:
which only displays start-up and critical messages.  Presently any non-zero 
value will display all soft messages as well.  NB This does not turn 
debugging messages on, that must be done by modified the source code.

Variable MTU size:

The driver can handle a MTU size up to either 4500 or 18000 depending upon 
ring speed.  The driver also changes the size of the receive buffers as part
of the mtu re-sizing, so if you set mtu = 18000, you will need to be able
to allocate 16 * (sk_buff with 18000 buffer size) call it 18500 bytes per ring 
position = 296,000 bytes of memory space, plus of course anything 
necessary for the tx sk_buff's.  Remember this is per card, so if you are
building routers, gateway's etc, you could start to use a lot of memory
real fast.

2/17/02 Mike Phillips