Attempt fix for connectivity issues

Suspected cause: multicasting not working for nodes with
an interface 0 due to lack of 'mirroring_add 0 0' line in
hp4commands.txt

hp4/hp4commands.txt

+mirroring_add 0 0
 mirroring_add 1 1
 mirroring_add 2 2
 mirroring_add 3 3