Why can't Windows 95 Boxes talk to BSD/OS 3.0 boxes?

Subject: Why can't Windows 95 Boxes talk to BSD/OS 3.0 boxes?
Date: 11/13/97

BSD/OS 3.0 introduced Path MTU discovery. Unfortunately Windows 95 does a rather poor job of dealing the MTU's and MRU's. It will gladly negotiate an MTU/MRU it cannot cope with. There are two sysctl variables in BSD/OS that can be tuned to assist in this:

net.inet.tcp.43maxseg

Setting this value to 1 will basically turn off Path MTU discovery for inbound connections. This will limit inbound packets to 536 bytes so it should only be used if you really need it. It would be best to fix Windows 95 so that it does not try to use things too powerful for it to handle.

To adjust outbound Path MTU discovery the following sysctl may be changed:

net.inet.tcp.pmtu

Setting this to 0 will disable outbound Path MTU

Of course, this begs the question, why continue to use Windows 95? For networking you should use BSD/OS from BSDI and for desktop applications a Macintosh.