math behind data-link interface policies

I am trying to evaluate the pros and cons of the different policies for  data-link interfaces.

What is the math behind the 3 options?

from:  dladm(1M)

     -P policy              Specifies the port  selection  policy

     --policy=policy        to use for load spreading of outbound

                            traffic. The policy  specifies  which

                            dev object is used to send packets. A

                            policy consists of a list of  one  or

                            more  layers  specifiers separated by

                            commas. A layer specifier is  one  of

                            the following:

                            L2    Select outbound device  accord-

                                  ing  to  source and destination

                                  MAC addresses of the packet.

                            L3    Select outbound device  accord-

                                  ing  to  source and destination