Re: IBM Token Ring problem -- "large" data amount problems
Paul Norton (pnorton@ccnusa.com)
Thu, 16 Jul 1998 08:44:10 -0700 (PDT)
Up until very, very recently you were limited to a 2,000 byte MTU with
the ibmtr driver. I have a patch in pre-2.1.109 that removes that
limitation and allows an MTU of up to 17,848 provided you have enough
shared ram allocated on the adapter. If you specify an MTU greater
than 2000 with the older driver you'll probably be O.K. receiving
frames greater that 2,000 bytes as leftover shared ram is allocated as
receive buffers, but the transmit buffer size is only 2,048 bytes in
size. That means if the kernel assembles a frame larger than 2,048
bytes (you told it it could via the MTU) then you'll get that error
when it tries to copy the frame into the adapter buffer.
Try setting the MTU to 2000. As I mentioned above, you'll probably
still be O.K. receiving 4K frames and the 2,000 byte MTU will prevent
the kernel from trying to assemble a frame for transmission larger
than the adapter can handle.
Scott Smyth writes:
> It looks like they were doing 4K packets using the token ring.
> The MTU was set correctly on the linux box, but the other token
> ring cards were set a little high. Does that sound consistent
> with what you are suggesting?
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