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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

118.0. "FDDI max packet size?" by CRLVMS::VAITZBLIT () Tue Aug 21 1990 11:05

	Hi,

The maximum FDDI packet size is 4495. The spec states that the maximum size
is limited by the nature of the clocking.

For reasons specific to my application and the 3Max FDDI adapter it would be
extremely convinient if the max FDDI packet size were 4096+512=4608

If I change the driver to support the FDDI packet size of 4608, would I break
the physical protocol? Or might it still work with the max packet size of
4608?

Thanks in advance for any comments.

Regards,
Lev.

T.RTitleUserPersonal
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118.1Since this is in violation of the standard, why bother?CVG::PETTENGILLmulpFri Aug 24 1990 01:2111
Ask Dirty Harry says, `How lucky do you feel today?'

Obviously whether you can do it at all depends on the hardware.

If you can do it with the hardware, then the question is, are the clocks
on adjacent stations on you LAN closer in speed than is required by the
FDDI spec.  If not, then the bit rate that the data arrives at one stations
will either overflow or underflow the elasticity buffer and the the packet
will be damaged.  If this does happen at all, then it will tend to happen
a lot.  It isn't enough to worry about the sending and receiving stations,
you must also worry about every station in between.
118.2second the motion!KONING::KONINGNI1D @FN42eqMon Aug 27 1990 15:585
If you do that it won't be supported.

Do you still want to do it?

	paul