i was reading about the Vlan and to be more specific the disadvantages of VLAN and the information resource mentioned that Vlan has Device limitations as follows :
Device limitations :
The number of Ethernet addresses that can be supported by each device is 500. This is a distribution of about 20 devices per port on a 25 port switch. In an ideal network situation, there is one device per port, for example, a printer, a workstation, and voice IP phone will require 3 ports. If you wanted to have one VLAN assignment for each port, then the maximum VLANs will equal 25.
so what does that mean "The number of Ethernet addresses that can be supported by each device is 500" ? does this mean that the switch (the 25 ports switch ) can handle up to 500 device that's 20 device per / port (assuming each of these are connected to switch which is in turn connected to the 25 port switch ) ?
or it is just bad example ?
and it follows with another disadvantage of VLANs saying :
If a hub or switch is connected to one port, every port on that hub must belong to the same VLAN. Hubs do not have the capability to provide VLANs to individual ports, and VLANs can not be extended beyond the device port even if a switch capable of supporting VLANs is attached.
when it say " every port on that hub must belong to the same VLAN" , as i know hubs are layer 1 devices so they don't understand mac address or deal with Ethernet frame that could had tag field inside of it then they don't understand Vlan , so how is this possible ?
So are these info correct or i have to find another resource ?