PLEASE leave your multicast sessions up!

[Bill Nickless]

Network people at several institutions, including Access Grid sites and
service providers, are trying to debug the wide area IP multicast problems.
 Access Grid requires high bandwidth IP multicast, which pushes the current
best practices of networking to the edge.

I received this from a network person trying to debug the IP multicast
infrastructure for Access Grid:

>What can I say, APPS and SYS ADMIN's always abandon us network folks
>in our time of need. Looks like they are gone and the test system has
>been shutdown on our end. I don't have a login that I can use to try
>and fire it up and I don't have another platform set-up to initiate
>sessions so it looks like we are done until some time tomorrow. Until
>then,

Remember what I wrote yesterday--there is NO state preserved for network
debugging when the multicast client on your workstation is stopped.  None
at all.  In order to find where the IP multicast problems are lurking
through all the various networks, you as an Access Grid person MUST leave
the multicast clients (like vic and vat) up and running--both receiving
*and* transmitting.

Often network people work strange hours, or can only get to interesting
problems like this after fighting daytime fires.  Sometimes network people
have to telephone other network people, call in personal favors, and send
email back and forth with router configurations and status.  This can take
time.  It is impossible if the IP multicast clients are turned off in the
middle of all this behind-the scenes activity.

Please, please, PLEASE leave your multicast sessions running so that the
network people have something to trace with.  Day and night, over the
weekend, etc.

On the other hand....

If you're one of the VERY helpful people who has already been leaving their
vic and vac up and running day and night for us--I thank you from the
bottom of my heart, and may your tribe increase!  (Consider yourself
positively reinforced.)
--
Bill Nickless    http://www.mcs.anl.gov/people/nickless      +1 630 252 7390
PGP:0E 0F 16 80 C5 B1 69 52 E1 44 1A A5 0E 1B 74 F7     nickless at mcs.anl.gov