[AG-TECH] multicast "iffy" across the Great Divide

David Mitchell mitchell at ucar.edu
Thu Apr 11 14:56:02 CDT 2002

Don Morton wrote:
> is anybody aware of problems that seem to have been around
> since at least yesterday (when our multicast got fixed)
> whereby, at least in venues, west coast sites (i.e. those
> approximately west of the continental divide) and east
> coast sites get "split" on a periodic basis?

We're definitely having problems at NCAR also. I haven't looked
into it enough to determine any geographic pattern. In our case,
it actually seems to be more like the traffic starts and
stops on a somewhat regular basis (every few minutes). It also
only seems to be affecting actual AG sessions. Our mcast beacon
looks OK.

I've been playing with the 'show ip mroute count' to try and
find out where the failure is, but haven't been able to
track it down yet. Last time we were having the problem, I
was able to verify that the Abilene routers in Denver and
KC were not forwarding any significant number of video packets
from ANL when they problably should have been. I wasn't
able to determine where the traffic was stopping, though. The
delay on the Abilene 'looking glass' page is understandably
significant, so it's tough trying to debug that way.

At this point, it seems like we need to open a ticket with
the I2 folks to look into it, maybe. Any volunteers to head
this and follow thru on it?

-David Mitchell

> in the "open test" session today, we had constant connectivity
> with uc davis and unm, but would lose such connectivity
> with more eastern sites very periodically, including ndsu
> (marty, i'm virtually sitting on my hands, refraining from
> making a joke about this!! :)), nsf, and anl.
> actually, i guess unm must be "just east" of the divide, since
> the rio grande runs through albuquerque.....
> i notice in the lobby we experience same sort of behaviour....
> --
>    Don Morton                   http://MRoCCS.cs.umt.edu/~morton/
>    Department of Computer Science       The University of Montana
>    Missoula, MT 59812 | Voice (406) 243-4975 | Fax (406) 243-5139

| David Mitchell (mitchell at ucar.edu)       Network Engineer IV  |
| Tel: (303) 497-1845                      National Center for  |
| FAX: (303) 497-1818                      Atmospheric Research |

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