how many private vlan can be create on a switch?

[gilel2004]

lets say I have a switch that support VLANs up to 255, and supports Private VLANs.

how many primary VLANs can becreated and how many secondary VLANs (at each primary)?

[mmellet]

Private VLANs provide Layer 2 isolation between ports within the same private VLAN. Hence the number of private vlans supported in the switch would be 255. Based on the traffic flow accross the ports, the vlans are categorized as primary vlan or secondary vlan.

primary VLANCarries traffic from promiscuous ports to isolated, community, and other promiscuous ports in the same primary VLAN.

isolated VLANCarries traffic from isolated ports to a promiscuous port.

community VLANCarries traffic between community ports and to promiscuous ports. You can configure multiple community VLANs in a private VLAN.

Isolated and community VLANs are called secondary VLANs.

Only one isolated VLAN can be mapped to a primary VLAN, but more than one community VLAN can be mapped to a primary VLAN.