forys@boulder.UUCP (03/29/87)
The setup; We have an 11/785 running 4.3final (patch level 8) as our
gateway (delua/deuna) on a Class B, subnetted network (netmask=0xffffff00).
All but 1 machine on the subnet doesnt understand Class B subnets so we
use the subarp hack on this gateway. The problem is that this gateway
also propagates rwho packets to/from the subnet to give users that `one
big happy network' feeling. :-)
Well, when I ifconfig the broadcast addr to `128.138.0.0' (this is what they
*have* to be so that all the 4.2-style machines understand), the broadcast
packets didnt know which interface to use, hence the packets never got out.
Now, while changing the broadcast address to "128.138.subnet.0" worked (i.e.
the broadcast packets got out), the other machines would not interpret them
as broadcast packets because of the subnet number.
The only way I was able to make all this work was by setting the broadcast
addresses to `128.138.sub.0' and changing the destination field on every
broadcast IP packet destined for our net to `128.138.0.0' in "/sys/netinet/
ip_output.c". Has anyone come across this problem? Is there a *nicer* way
to handle it? Have I missed something obvious?? ...thanks!
---
Jeff Forys @ UC/Boulder Engineering Research Comp Cntr (303-492-6096)
forys@Boulder.Colorado.Edu -or- ..!{hao|nbires}!boulder!forys