All things related to multicast

[Caren Litvanyi <>]

Hello mcast folks; I thought people here might be interested in the
following, sorry if you've seen it on other lists already.

The following URL summarizes the results of a survey concerning 
people's ability to use multicast (or not) for accessgrid sessions.
It made the rounds on the ag-tech and beacon mailing lists a couple
weeks ago, but I didn't see anything about it in the archive here.
  http://www.andrewpatrick.ca/multicast-survey/
(by Andrew S. Patrick, Senior Scientist, Information Security Group,
Institute for Information Technology, National Research Council of
Canada). 

It is all interesting stuff, but one part that caught my eye
from Internet2/Abilene's point of view was this:
    'Perhaps a related theme was that many multicast problems
    arise at the local level, often at the scale of the 
    individual LAN (mentioned 4 times). For example, one 
    participant wrote: "Multicast on the WAN is ok, on our 
    Lan is a problem."'

Last Fall, Alan asked the list for LAN war stories and got a few
interesting responses, but I was not really able to incorporate
the issues raised in any troubleshooting that we teach as part of
the I2 multicast hands-on workshops.  They seemed somewhat vendor-
specific, with the only solution being to recommend a different
vendor.  We stay away from vendor advice or bashing as best we can
in our workshops.

Other potential problems I have heard involve HSRP or VRRP
interaction with PIM.  I do not have the gear to build this
scenario in a lab.  Can anyone here relate specific experience
with HSRP breaking multicast?  Or how they got multicast working
with HSRP?  Or can report "it just works"?

I would be very grateful to people who can relate scenarios 
where some local/LAN network configuration or design "breaks"
otherwise properly configured multicast, and how you discovered
and fixed the problem.  So this is sort of a re-issue of Alan's
request for LAN issues.  Particularly if you were able to work
around them with some configuration or topology change.  I have
not run a very large campus LAN since about 1999, so I don't have
recent experience to help people in this area, and am somewhat
at a loss.

Also, any other discussion on the survey results would be very
welcome.  I emailed the author and he would like to hear a
summary of any comments here.  Note the actual text responses
are available as a link, "50 responses".

Thanks!
Caren
------------
Caren Litvanyi, network engineer
Global Research NOC at Indiana University

o:812-856-4576  c:720-839-7739