[evla-sw-discuss] Multicast TTL

[James Robnett]

We should make sure that all multicast traffic has a TTL of 5.

When we started using multicast the distance from EVLA transmitters to
AOC listeners was 4 hops.

2 years ago we consolidated the EVLA router and core switch into one
box which reduced that to 3 hops.   Yesterday we replaced the AOC
core switch but left the old one for the time being which increased
the hop count back to 4 which meant anything with a TTL of 3 no longer
made it to the AOC.

If we want to limit mcast packets to just the VLA site the hop count
should be 2,  if we want to allow packets to any NRAO site it should be
9 (maybe 10 I'd have to double check some routes).

James