Hello Mhiyoshi,
>> I would like to know the basic understanding and the method of calculation.
let's consider at first a two members etherchannel and let we number the member links with an index
index 0 member 1
index 1 member 2
let's say we have an IP flow
source address = 10.10.75.1
Destination address = 10.20.25.3
to decide to what member link to send the packets of this flow the operation to be performed in a boolean EXOR of less significant bit
1 => 0000 000|1
3 => 0000 001|1
1 exor 1 = 0 => use member1
A same reasoning is used if the number of member of links is greater then two
if you have 4 links you need to exor the last two digits
if you have 8 links you need to exor the last three digits
this kind of operation can be performed on MAC addresses too.
bundles with a number of links that is not even can be accomodated by making the calculation on an higher number of digits and by mapping the results to the member links more then one time.
this is the meaning of the table that appears in the link that you have provided, notice that the sharing is less fair for example with 7 links:
2:1:1:1:1:1:1
you have 8 slots so one member link is used two times for two different results of the calculation
Actually the document suggests that the calculation is performed always on the last three digits with a bit to bit Exor
because 8 is the max. number of member links ( note that modern LACP may go beyond )
Hope to help
Giuseppe
be also aware that high end switches like C6500 are able to use different load balancing methods for different type of traffic so they use IP SA and IP DA for IPv4 traffic, mac addresses for non IP traffic.
