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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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