Linux-Hams archive - June 1997: Re: Oops...

Re: Oops...

Joerg Reuter (terhi.victor@logonet.com)
Sat, 07 Jun 1997 20:32:16 +0200

> In the message I posted a minute ago I wrote:
>
> > The heart of the question is, if I want to be able to run ethernet-sized IP
> > frames over ax25, do I only need to set the interface MTU, or must I set the
> > /proc/sys/net/<port>/standard_window_size parameter as well?
> ^^^^^^^^^^^^^^^^^^^^
>
> I *meant* "maximum_packet_length".

The maximum_packet_length applies to virtual connect mode only.
For mode dg with 1005 bytes of data field per UI frame just set the MTU
to 1005.

An MTU 1005 with maximum_packet_length set to 256 will enable fragmentation
on the AX.25 layer (which is a Good Thing (tm) when IRTT and Window
are carefully chosen). Maximum_packet_length set to a higher value
will result in overlong I frames, which is a IMHO a Bad Thing (tm), as
most AX.25 and KISS implementations do not support a data field longer
than 256.

Thus, just leave standard_window_size alone and the Kernel AX.25 will
do the right thing.

73,
Joerg Reuter ampr-net: ake.mynlikxu@telekarelia.fi
Internet: terhi.victor@logonet.com
www : http://www.rat.de/jr/

Fur? I'd rather grow my own!