debugging SLP problems on Mac OS 9/X
debugging SLP problems on Mac OS 9/X
- Subject: debugging SLP problems on Mac OS 9/X
- From: Smith Kennedy <email@hidden>
- Date: Tue, 8 Feb 2005 19:15:39 -0700
Greetings,
I was wondering if anyone might have any insight into a problem we are
having with Mac systems on our site. The problem seems to involve SLP
on both Mac OS 9 and Mac OS X.
I posted a related message to the client-management ML a while ago, but
got no meaningful replies (thanks to John Welch for trying, though).
A couple of months ago, for several days, there were these "multicast
packet squalls" that would occur periodically, and would be visible on
all our subnets on the site. Each "squall" consists of 250K or so SLP
service request queries being made within 1-2 minutes. All queries in
a particular "squall" would emanate from the same system, and the
system was always a Mac OS 9 or Mac OS X system. However, each squall
might come from a different Mac system (I have counted about 6 so far).
The squall would consume / utilize about 90% of the available network
bandwidth, and would also cause huge CPU loads on other Mac systems. I
am assuming this is because the Macs are always configuring their NICs
to listen for the same SLP multicast queries, so the NICs end up
accepting all the queries for processing rather than dropping them at
the card level. Not sure if this theory is correct. None of the
Windows systems or other computer systems on this site are configured
to care about the 239.255.255.253 multicast address, so they are not
burdened by this problem.
Disabling the SLP Directory Services plugin in "Directory Access.app"
will make the problems go away on the recipient systems. We have done
that, so this problem isn't showing up anymore on our site. But I am
concerned about this being caused by some of our own software systems
(possibly some badly configured Windows software), which is sending out
some bogus SLP messages saying that that host is an SLP DA, then not
responding to DA queries. I want to know the source of the problem,
not just settle for a kludge.
I did some long-running packet captures with EtherPeek, and I do see
some SLP queries coming from the Mac that later has the freakout, which
seem to be asking for a DA, and then, when no replies come back, it
goes nuts querying the network.
My questions are these:
- Does anybody have any hunches why this would be happening?
- Would the Mac OS X system start to do this behavior in response to
some kind of broadcast or multicast? My theory is that there is some
type of message that the Macs are responding to that cause them to
freak out like this, but I am not sure what the cause is. Perhaps I
didn't manage to capture the entire cycle, because it could be the
absence of a response that is making the Macs freak out.
- Is there any way to put the SLP system in Mac OS X into a mode that
will make it dump trace messages to a log? I don't see any messages on
the system.log or console.log when these happen.
Any ideas would be very helpful. Thanks for any info you can offer!
Smith
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