A peer on another discussion forum suggests the following:
'I doubt that you can find one [an LACP calculator] due to the fact that LAG hashing is hardcoded in switch controller and therefore is chipset specific (even the same vendor can use multiple different ones).
"Hash can be computed based on MAC address, IP address or L4 port (at least those are available in modern Broadcom chipsets) so there are plenty of possibilities.
"And since every chipset vendor considers its design as confidential, it will be hard to discover unless you'll find someone that has programmers documentation to a particular chip.
Hello Stuart, It is true... You can't really be confident and say, this port in this etherchannel will be selected, unless you know the values and hashes to be able to work it out- (too much work ). And I'd also add that it depends on the vendors 'hash' that they use to calculate the values.
Not all vendors have the same hash. And ports have different field values associated too which can make it unpredictable.
EtherChannel reduces part of the binary pattern that the addresses in the frame form to a numerical value that selects one of the links in the channel in order to distribute frames across the links in a channel. EtherChannel frame distribution uses a Cisco-proprietary hashing algorithm. The algorithm is deterministic; if you use the same addresses and session information, you always hash to the same port in the channel. This method prevents out-of-order packet delivery.
The Cisco-proprietary hash algorithm computes a value in the range 0 to 7. With this value as a basis, a particular port in the EtherChannel is chosen. The port setup includes a mask which indicates which values the port accepts for transmission. With the maximum number of ports in a single EtherChannel, which is eight ports, each port accepts only one value. If you have four ports in the EtherChannel, each port accepts two values, and so forth.