leres@helios.ee.lbl.gov (Craig Leres) (01/07/89)
Gunnar Lindberg writes: > I guess this depends on what SunOS you run, but for 3.x (x >= 4) the > discless clients simply broadcast an "icmp(ICMP_MASKREQ)" on the net > and use the first reply. File servers don't - instead they depend on This isn't quite correct. I don't remember if 3.3 or 3.4 was the first version to support subnets (whichever it was, it the support was in the kernel, not the documentation) but all pre-3.5 systems that support subnets will gleefully accept and use any icmp netmask reply they receive. This generally means that they will use the LAST reply they receive. (Unless, of course, they get a bogus reply that renders their ethernet interface useless.) In 3.5, code was added to ignore obviously bogus netmask replies. Also, this version won't accept a netmask reply if the netmask has already been set. So it will use the FIRST reply and if you explicitly ifconfig the netmask, you don't have to worry about it changing on you. > 2) If the network is large, many hosts may try to answer, which > gives quite a peak in network traffic (first one ARP for > each reply, than the reply itself). This was discussed in > "comp.sys.sun" a while ago. In pre-4.0 systems, the symptom of too many replies was "nd boot error N" where N is an errno value (typically 12 or "not enough core"). Craig
pl@uunet.uu.net (Pertti Lehtinen) (01/16/89)
We also findout that atleast systems running OS4.0.1 very likely set their subnetmasks according broadcasts. It seems that if someone sends different mask than host has, host changes its mask, which causes nearly all network traffic to stop from/to that host. Very nasty this is with numerous workstations, because you aren't anymore able to log in. So all workstations have to be rebooted. So, be careful, no strange broadcasts, please. pl@tut.fi Pertti Lehtinen Tampere University of Technology Software Systems Laboratory