[AG-TECH] Multicasting questions

[Jon I Johansson]

Hello,

I'm just putting the hardware for our room based node together
(in my cubicle, the room isn't going to be ready for a while; 
sigh ...). I started up multicast beacons on the machines and
they seem to work fine, they showed up on the beaconserver
page at http://beaconserver.accessgrid.org:9999/loss.html.
I'm currently running one beacon client on a machine with
IP address 129.128.11.103.

The first thing I notice when I look at the Loss page is that
I have lots of green entries along the horizontal axis
(is this for my packets being received by another machine in
the multicast group?) but nothing along the vertical axis
(others send but I receive nothing?). 
I thought I saw a link to a description of this table but I can't
find it now, but as I look at the Task Manager I have 100 times
more multicast information being sent than received. Is my 
interpretation correct? Is there any "usual" reason for this
behavior?

In looking at the Delay page I seem to have a half second delay.
Should this worry me? There seem to be plenty of delay entries
on that page that have a fairly consistent delay in a row, is 
that just a sign of poor clock synchronization? I am using AtomTime
to get the time from an NTP server, and I've tried the default
time server and our local one with the same results.

I'll try to leave my beacon client running for a while if it
is useful for anyone to look at the results.

Now for the harder questions:

How much impact can I expect the multicasting from an AG node
to have on the rest of the network? Is it worthwhile or necessary
to have a dedicated line for the AG node to isolate the traffic?
I'm going through the tutorials that I can find on this but 
I don't have much experience with networking issues so any guidance
on pitfalls and useful approachs for would be greatly appreciated.

Thank you,
Jon.

-- 
Jon I Johansson             *  Research Computing Support
jon.johansson at ualberta.ca   *  Computing and Network Services
Tel.: (780) 492-9304        *  University of Alberta
Fax.: (780) 492-1729        *  Edmonton, Alberta, CANADA