[AG-TECH] Net Split?

Don Morton morton at cs.umt.edu
Thu Mar 29 23:21:48 CST 2001

So, there I was in Bridgeport Room on Wednesday afternoon,
testing with Bob Huebert in Fairbanks.  Then, all of a sudden,
Gary Orser from Bozeman popped in, and we started to have a
conversation.  As it turns out, Gary couldn't figure out
who else I was talking to, and Bob thought I was out of my
mind.  In other words, I could interact with both Bozeman
and Fairbanks, but neither of them had any interaction with
each other.  It seemed quite strange, and we were all wondering
what the possible cause might be.

Some specifics...

- I was, as usual, using the ANL bridge (I "think" this means I
  was unicasting to ANL, who in turn multicasted me via the bridge)

- Both Bozeman and Fairbanks were multicasting

- The multicast beacon showed that both Bozeman and Fairbanks
  were getting out to numerous sites, but the intersection of
  their beacons showed a grey "N/A."  

- From time to time Bozeman's audio would drop from my rat and
  even their "handle" in my rat would disappear, for maybe 30-60
  seconds at a time (and his video would freeze).  So, I couldn't 
  hear them but, Gary tells me he could hear and see me the whole 
  time (poor guy).

- Fairbanks brought in one of their network guys during all this, who
  tried some pings and found that "packet filtering" was occuring at
  our Gigapop in Seattle (I think that's where it is).  Gary and I
  both recalled that Montana institutions had, a couple of weeks earlier,
  initiated some sort of block on ICMP.  This may have no relevance 
  whatsoever, but I thought I'd at least mention it.

So - is this somewhat "normal" behaviour?  Is there anything we could
have done to rectify the situation?  In some cases it was quite
humourous - both Bob and Gary would try talking to me at the same
time, having no concept that they were walking over each other
(old CB lingo for you old-timers out there!).

   Don Morton                     http://www.cs.umt.edu/u/morton/
   Department of Computer Science       The University of Montana
   Missoula, MT 59812 | Voice (406) 243-4975 | Fax (406) 243-5139

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