Shared ports is what I meant to say. Flow are the layer 2/3/4 traffic going through the ports from ingress to egress on your shared ports. From my understanding of how the the sharing algorithm works is ...
Layer 2 it looks at source and destination mac for each of your tcp or udp connections and shares this across the port shared group... So if there is a 2 port share and you have 2 sets of source and destination macs one set would be on one port and the next set would be on the other port. Layer 3 also looks not only at macs but at ip source and destination so you have one more way to split your traffic apart. Layer 3-4 also looks at layer 4 info to break apart traffic.
So you can see if you were using only layer 2 and had 2 routers on one side and 2 routers on the other side that is only 2 sets of macs at layer 2 and one router set would be on one port and the other router set would be on the other port for each connection the routers generate.
Port sharing never just looks at packet count or bandwidth so that is why you can have larger amounts of traffic on a single interface of a port share group.
Mcast and broadcast frames typical have a common destination mac so that traffic is even less likely to be spread across more than one port for each of the flows being generated be your routers or clients.
People think of port sharing as a way to get more bandwidth but it truely depends on what type of Ethernet traffic you are pushing across your switch.
These are my findings from being a layer 2 network providor using extreme for 20 plus years. They may not have all the true technical info of how the switch choose to forward traffic when you have a LACP port group and share enabled, but this is my understanding of how it works and for sure my real world experience. We use L3/L4 on all our port shares.
One other issue you will run into is when you hand off to another vendor.. in to out is what you control.. so traffic from your switch to another vendor .. you can't influence what they send you. Most vendors today use some sort of L3/L4 ...
Thanks for the reply. Pardon my ignorance but what do mean by ports not a good way to balance traffic. Also when you mention flows, are you referring to the physical connections or is that a programming function.
It's easier to see on a screenshot (as copy/paste messes up the format) but as far as I'd see flag for Ld Share Algorithm is L3 = Layer 3 address based.
You'd change it with this command....
Switch_1.2 # configure sharing algorithm address-based ?
L2 Based on layer 2 MAC (default)
L3 Based on layer 3 IP
L3_L4 Based on layer 3 IP and layer 4 port
custom Based on selections in 'configure sharing address-based custom'