The RIPE NCC Test Traffic boxes form a very useful measurement
platform, distributed over a large number of provider networks.
IP Multicast monitoring is inherently difficult, as you cannot
easily probe connectivity from a single point of view - some problems
need testing and monitoring from multiple different locations
to identify "black holes" on some paths.
When troubleshooting connectivity issues spanning multiple networks,
things are a lot easier if a neutral entity does the monitoring
and pinpointing of problem areas.
I think the RIPE NCC Test Traffic network is uniquely qualified
to do this.
b. Arguments opposing the proposal:
Some arguments have been brought forward that there are not enough
multicast-capable networks to make this a worthwile action.