Subject: DEC Alpha OSF/1 3.2C mrouted problems

From: "Alan J. Flavell" <[email-masked]>
Date: Sun, 19 Oct 1997 16:42:29 +0100 (BST)

Dear Colleagues,

We've been running mrouted on a DEC Alpha OSF/1 platform for a
considerable time now, with a tunnel from a Sun workstation in our
computing service.   (I'm from the Physics dept, if that's of 
interest ;-)

A little while back, we upgraded the OS to 3.2C, and re-fitted the 3.5
multicast modifications, and continued to run mrouted 3.8 as before.  This
went without apparent incident. 

In the last few days, though, we got our tunnel moved off that old Sun to
a higher performance beast.  And immediately our workstation's OS started
crashing.  It's crashed now nine times in the space of about two days,
once three times within an hour. 

The information in the crash-data files isn't always the same, so it seems
it may be consequential damage from some problem that hadn't given an
obvious error.  I have to say frankly that as a "jack of all trades and
master of none" I have very little experience in debugging this kind of
thing. 

We aren't (from the crash-data reports) anywhere near running out
of swap space.

One frequent crash report is:

  trap: invalid memory read access from kernel mode 

Others are:
  panic (cpu 0): m_copym length    
  panic (cpu 0): freeing free mbuf 

p.s there _is_ only one cpu (i.e 0).

Researching the problem via a search engine, this vaguely resembles a
situation reported for Digital Unix 4.0B, but we are running (and
currently have no plans to go beyond) 3.2C. 

I suppose we could consider running mrouted on some other architecture. 
Strange that this problem only started when we moved our feed. 

We in turn are feeding a tunnel to another DEC Alpha station with a very
similar configuration, and that one hasn't crashed.  Whatever it is that's
killing us, we aren't passing it along to the other dependent mrouted. 

Any advice would be welcomed.  The problem mrouted is a4.ph.gla.ac.uk, if
anyone feels a need to throw mrinfo etc. at it.  Its tunnel is being fed
now (I think I'm expressing this roughly correct) by the mrouted function
of a BayNetworks (ex wellfleet) router at the campus's computer centre.

best regards

---

From: "Alan J. Flavell" <[email-masked]>
Date: Fri, 24 Oct 1997 16:15:52 +0100 (BST)

I recently wrote to this list about crashes due to mrouted
on the above platform...

On Sun, 19 Oct 1997, Alan J. Flavell wrote:
...
> once three times within an hour. 
..
>   panic (cpu 0): freeing free mbuf 

I didn't receive any replies, so I took some more time to look around
the software archives, and at

  ftp://ftp.adelaide.edu.au/pub/av/multicast/OSF1/

I found there were two archive files:

    ipm35_decosf_v32.tar.Z . . . . .  [Nov 27  1995]    403k
    ipm35_decosf_v32_1.tar.Z . . . .  [Dec 12  1996]    394k

I had been getting my software from an archive near to me, usually
the MICE archive at Edinburgh.  That contained something different:

ftp://mice.ed.ac.uk/pub/videoconference/ipmulticast/DEC/Digital_Unix_3.2/ipm35_decosf_v32.tar.gz

Nov 29  1995  GNU Compr. Tar   ipm35_decosf_v32.tar.gz  291Kb     

which seems to be an alternative packaging of the earlier version.

Also, at

http://nic.merit.edu/~mbone/index/titles.html

the relevant link is pointing to the _OLDER_ version at the
Adelaide site.

I retrieved the newer version from the Adelaide site, and lo and
behold, its README contains the following note:

  CHANGES from the previous ipm35_decosf_v32 and this ipm35_decosf_v32_1
  kits:

        o 3.8 mrouted and tools (vs 3.6 in previous kit)
        o Several *critical* fixes in ip_mroute.o, igmp.o, route.o files
                - fix panics due to bug in timer processing
                - viftable counter fixes
                - packet corruption fixes
                - properly calling expire_upcalls

and also says

  Note that this kit has been tested by field test sites from Digital UNIX
  3.2a through 3.2d releases.

Great: so I de-installed the old multicast mods, installed these
in their place, and rebuilt the kernel.

So far, on the basis of only a day or so running, all is working well.

I don't recall seeing this discussed, and I didn't find anything via
web search tools etc., so I thought I should place it on record, and
hope that anyone who knows better will speak up.

I'm copying this explicitly to the email addresses given on the web pages
at the two archive sites cited, so that they may consider what to do about
it.

Best regards.

---

From: Graeme Wood <[email-masked]>
Date: Fri, 24 Oct 1997 16:47:00 +0100 (BST)

> at the two archive sites cited, so that they may consider what to do about

I'll update my link with the newer version. (I assume that is what you are
hinting at :) )

Graeme

=============================================================================
Graeme Wood                                 Email: [email-masked]
Unix Systems Support                        Phone: +44 131 650 5003
The University of Edinburgh                 Fax:   +44 131 650 6552
=============================================================================

---

From: "Alan J. Flavell" <[email-masked]>
Date: Fri, 7 Nov 1997 22:10:35 +0000 (GMT)

Further burrowing in mbone software versions has produced another
little surprise.

I had found (thanks to Graeme) the mrouted version 3.8.4 for DEC OSF/1,
and thought I was doing the right thing to use the version of mtrace that
came with it.  I don't see anything in Graeme's archive to say otherwise. 

Also the information at www.merit.net seemed to be saying that 
the mtrace tool came with the mrouted package (which indeed a
version of it does).

However, if one goes to ftp.parc.xerox.com in the directory
pub/net-research/ipmulti/ then it transpires that mtrace has been split
off from the mrouted package and given its own version number, 5.1. 

Of course the file last-change date could be misleading, but I have the
impression not only that the "5.1" version is quite a bit more-recent than
what was included with the (3.8.4) mrouted, but also (unless I'm fooling
myself!)  that it's behaving better than the older version. 

I see that mtrace 5.1 is available as binaries for four different
platforms, as well as source. 

Any corrections to my "discoveries" gratefully received.

all the best

---

From: Bill Fenner <[email-masked]>
Date: Fri, 7 Nov 1997 16:07:15 PST

>I had found (thanks to Graeme) the mrouted version 3.8.4 for DEC OSF/1,

Boy, do I wish people would stop giving random version numbers to
their mrouted releases.  This is the first time I've heard of "version 3.8.4".
Vendors, please check the LICENSE file before releasing things...

>off from the mrouted package and given its own version number, 5.1. 

Yes, this is true.  Since I know nothing about the 3.8.4 mrouted, I
can't say what mtrace might be included with it, but the 5.1 mtrace
release does indeed have several improvements over the 3.8 mtrace.

  Bill

---

From: Graeme Wood <[email-masked]>
Date: Sat, 8 Nov 1997 09:04:13 +0000 (GMT)

It has been on my archive for ages.  You can find it in
ftp://mice.ed.ac.uk/pub/videoconference/util/mtrace/.

Graeme

> release does indeed have several improvements over the 3.8 mtrace.

I think it is the one that shipped in the original 3.8 distribution.