Hello Bassam
You are indeed correct. These commands result in the creation of a community VLAN 501 which is not associated with a primary VLAN. Actually, in my emulator, I get the following putout for the show vlan private-vlan command:
SW1#show vlan private-vlan
Primary Secondary Type Ports
------- --------- ----------------- ------------------------------------------
500 502 isolated
none 501 community
This explicitly shows that 501 is not assigned to any primary VLAN. Thanks for pointing this out, I will let Rene know to consider making changes to the content to clarify.
The primary point of this lesson is to show how VTPv3 is able to share information about private VLANs, and this is done successfully. However, if you want to find out more about private VLANs and how to configure them, you can take a look at the following lesson which shows more detail:
I hope this has been helpful!
Laz