Vax 4.2 UDP Bradcast woes followup...

[romig at osu-eddie.UUCP]

From: romig (Steve Romig)

About two weeks ago I posted a description of a problem we were/are
having with broadcast UDP's between a {Sun, Pyramid} and a Vax, all 
running 4.2.  Short description:  Broadcast UDP's worked fine between
the Suns and the Pyramid, both directions.  Rwho and ruptime work just
fine, and some simple programs using broadcast packets also work fine.
On the Suns and the Pyramid, the command "/etc/ifconfig <interface>"
claims <UP, NOTRAILERS, BROADCAST, RUNNING>.  On the Vax, it just claimed
<UP, NOTRAILERS>.

The only problem mentioned to me so far is that some forms of "ifconfig"
have a bug wherein it zeroes some of the bits in the interface's flag
word when you give it new options to turn on.  This means that the line
"/etc/ifconfig ec0 `hostname` -trailers up" turns off trailers and turns
on UP, but it also happens to turn off RUNNING and BROADCAST.  We fixed
ifconfig, and rebooted, and everything *ALMOST* works.  Thanks to *all*
(many responsese) who sent me mail - I appreciate it very much!  If these
problems sound familiar to anyone out there, let me know - the fix is 
simple (gotta read the flag word for the interface into the temporary
flag word you are munging with the flags before writing it back out 
again...).

The problem now is that the Suns and the Pyramid seem to be able to 
receive broadcast packets from the Vax, but the Vax does not seem to be
able to receive broadcast packets from them.  Fer example, rwho on
a Sun will tell you who is running on the Suns, Pyramid, and Vax.
Rwho on the Vax says nothing.  Also, servers on the Vax don't seem
able to receive broadcast packets from the Vax, although Sun-Sun and
Pyramid-Pyramid broadcasting works fine.

Again, help, comments, etc. would be appreciated.  I will again give
my findings over to the net.

Thanks again to those who helped on the ifconfig problem!

				--- Steve Romig
				...!cbosgd!osu-eddie!romig
				romig at ohio-state.csnet