I have noticed that in my clusters that ESXi 5.5 hosts have their DVSsync port enabled, while the ESXi 5.1 hosts do not. And both flavors of ESX share the same distributed switch--which is version 5.1.
I am kind of curious as to why. The only information I can come up with about this service is from a firewall doc from vmware that simply states it is DVS port information between ESX hosts.
Anyway know a little more about this in depth? I am certain I did not disable this service/port on the 5.1 hosts.