Some experiences using ISC SLIP

[Michael Richardson]

A day or two ago I wrote:
>  I spend part of Thursday and Friday testing out a SLIP connection
>between fts1 (aka fts.ocunix.on.ca) and latour (aka
>latour.sandelman.ocunix.on.ca).
>  fts1 is a 25Mhz AMI Mark II 386 board running ISC 2.2
>  latour is a Sun 3/60 running SunOS 4.1(.0) with the streams based code from
>Rayan Zachariassen (UofT).
>  Both have 8Meg of ram and a T2500.

>  The biggest problem I had was with MTU sizes. RFC 1055, and my Sun
>slip stuff recommend a 1006 byte MTU in order to be compatible -- I
>can see the reasoning for increasing this with MNP modems. 

>  How can I decrease it with the ISC slip implementation? How can I
>even find out what it is? /etc/conf/mdevice.d/slip/Space.c 

  The above file revealed nothing at all. 
  This problem is really annoying me. I was about to increase the MTU
to  8192 on the Sun end (which just involves editing
/usr/include/sys/slip.h and recompiling) when I realized that it may
now be too big the other way. 
  Short of poking around the live kernel (which I may start doing in a
moment) how can I find out the value of ifnet->if_mtu? Neither
ifconfig nor netstat seem to allow me to do that.
  Can anyone offer any advice on poking around ISC 386/ix kernels?

  :!mcr!:
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