active-backup is active/backup .. requires ISL for HA and so on ..
but broadcast.. yes .. that sends the packets twice (thrice etc.), each
for and through every slave.. so theoretically the performance is the
same as if it was on a single link. practically there is some minor
overhead since the HW needs to queue the packet twice. But it might not
be that bad .. Need to test and measure…
Is active-backup more HA than broadcast ?
Practically
no it is not. maybe even broadcast is better … But theoretically (as
the viewpoint) active-backup implements HA technology – by failover ..
and broadcast is just … brute force ..
For
broadcast mode the packets will be duplicated if a hub or crossover
cabling is used. Normally pro-switches should clear out the duplicates.
But even with duplicates protocols like ssh etc works brilliantly.