load balancing mode of a LAG

[harri_waltari]

I need to check the load balancing mode of the lags on the physical switches (ICX6610, 08.0.30t) facing our esxi cluster. On the cluster side, at the virtual switches, the balancing mode is currently "Source and destination IP address". The manual is a bit vague of the modes and I can't seem to find a command to modify the mode in the physical switch.

The manual says (a snippet...):

Layer 2 Bridged TCP/UDP: Source and destination MAC addresses, source and destination IP addresses, and source and destination TCP/UDP ports.
...
Layer 2 Bridged IPv4 TCP/UDP  Source and destination IP addresses, and source and destination TCP/UDP ports.

So what is the difference here with "bridged tcp/udp" and "bridged ipv4 tcp/udp"? And are those different, selectable modes?

Eg "src & dst ip address and tcp/udp port" is one of the possible selections on the cluster side. Would that be a better combination for icx?

[vu_pham_ghtztqm]

Hi Hwa - I see your points. I think there is 'symmetric lag hashing' option that maybe be able to do what you're thinking, but it only work on IP packet and not Layer 2 packets. ICX6k don't support it, but ICX7K do. I don't know if VMware or Linux even support it. So it's not really a good option for load-balancing either.

Since lag hashing result is locally significant, I think even the hashing algorithm is the same on both LACP peer, it doesn't guarantee that the same pair of traffic will always get mapped to the same port on both end. What can be expected is that the ICX would always map SrcA/DstB to the same port as long as that port is up, this could be Port1 depend on the hash result of ICX. And similarly ESX would probably always map SrcB/DstA to the same port as long as that port is up, this could be Port 2 depend on the hash result of ESX.

At the high level on the ICX6K, when the traffic is Layer3 (being routed between VLAN/VE), it uses the IP headers and protocol fields in hashing. When the traffic is bridged/Layer2 (being switched in the same VLAN), it depends on the traffic type, IP and/or Ethernet headers along with Layer 4 ports info are used in hashing. I believe this is a standard method among vendors, and should be very similar between them.

Thanks,

Vu

[harri_waltari]

Vu, Thanks for you informative input. Really appreciate it. I think i get it now.