Motorola RFS7000 Reference Manual page 404

12-18 Motorola RF Switch CLI Reference Guide
How src-dst-mac mode works
When the switch sends a packet out of a SA, it selects the egress port as a function of the
packet's source MAC, destination MAC, and the set of ports in the SA which are running.
It XORs the bottom bits of the two MACs and indexes it into a table of the running ports.
How src-dst-ip mode works
When the switch sends an IP packet, the egress port is chosen as a function of the packet's
source IP, destination IP and the set of running ports. It XORs the bottom byte of the two
IP addresses and indexes then into the same table of running ports that
src-dst-mac
mode uses.
If the packet is NOT an IP packet, it uses the same calculation as src-dst-mac mode.
Why is src-dst-ip mode preferred
src-dst-ip mode distributes packets better when most packets, going through the gateway,
are IP packets. In the presence of an IP gateway, the IP packets forwarded from one MU
to hosts that is beyond the gateway all have the same MAC pair <MU MAC, Gateway
MAC> no matter what host the MU is accessing.
But in src-dst-mac balancing, the same link is selected always.