I config a 4+1 port etherchannel as:
port-channel load-balance dst-ip
lacp max-bundle 4
What will happen if one of the active interface (for example the 3rd interface) in port-channel1 fail? Will the algorithm re-calculate the hashing? Or just switch the traffic from 3rd port to the backup port?
the most efficient move is the second: the backup link takes the place of the failed link.
It should be possible because LACP messages are exchanged also on hot standby / backup links so the two devices can make a change on the fly with the backup link.
Hope to help