When you are defining multicast groups for applications, follow these
recommendations:
Bits 23 to 27 of the multicast address must not have the value 10100. This value is reserved for the Foundation Services.
Bits 0 to 22 of the multicast address should not have the
same value as any of your Foundation Services clusters.
When a message is sent, the IP stack uses the lower 23 bits of the multicast
address to define the destination MAC address. If several multicast addresses
have the same value for the lower 23 bits, even if they have different values
for the upper five bits, the addresses must be filtered at the IP level. The
IP filtering would create a corresponding reduction in performance.
Because of the way that hme and le interfaces filter multicast packets,
one in four clusters share the same multicast filter. To reduce the need to
filter at the IP level, clusters in the same LAN should have sequential cluster
identities.
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