tcp-ip@ucbvax.ARPA (08/16/85)
From: smoot%uo.UTEXAS@ut-sally.ARPA (Smoot Carl-Mitchell) I have backfitted the 4.3 subnet code into the 4.2 kernel. This change implements subnets as described in rfc940. We have been running it on our systems for about 2 weeks with no problems. In addition I also enhanced the ARP code in 4.2 to allow subnet gateways to answer ARP requests for hosts on a directly attached subnet or for a host on a subnet with a route through the gateway. This allows a site to use subnets by running the subnet kernel on gateway hosts only. This is useful in a heterogeneous environment where there are hosts running non-subnet kernels and the kernel sources are not available to modify them to know about subnets. Of course, it only works on ethernets or other LAN technology which supports ARP. The code is currently working on VAX hardware and should work on any other system running 4.2, since the modifications are machine independent. Diff listings of the mods and installation instructions are in the file pub/subnet.tar accessible by anonymous ftp on ut-sally.ARPA (soon to be sally.UTEXAS.EDU). Send any comments, bug fixes to me. I have also notified Berkeley and suggested they incorporate the ARP enhancement in future releases.