Service desk customer - portal access VS Service Desk Customers

Question

Hi.

I read a lot about this but still don't understand.

I sync AD users (customers) to my Jira Service Desk instance.
All customers are in an AD group 'jsd-customers'.
In my project 'Helpdesk', this AD group is mapped to the Role 'Service Desk Customers'.

Then I went to the Permission Scheme in order to allow or not what people can do when raising a ticket. That is when I encounter this 'Service desk customer - portal access' security type.

1) I read that I should not set permissions to the Role 'Service Desk Customers' in the Permission Scheme, that it should be handled by the 'Service desk customer - portal access' security type.
But how does the 'Service desk customer - portal access' security type knows who are my customers??

2) I read that this 'Service desk customer - portal access' security type is good to prevent customers to have access to the Jira side of Jira Service Desk (as opposed to the Portal side) but I don't need to prevent anything : they are not licensed so they can't log in the Jira side anyway! 
Can someone explain what I was supposed to understand here?

3) By default,  the 'Service desk customer - portal access' security type is granted to a lot of Issue permissions in the default project Permission Scheme.
Like "Assign Issues". But with my test user, I don't have the ability to assign my portal-created issue to anyone, in fact I can't even see the setting.

So, is this security type really used and do you confirm I should not use my  'Service Desk Customers' Role? 
Why is there even a  'Service Desk Customers' Role if we can't use them to assign permissions in a Permission Scheme???

Thanks a lot !!!!

Christophe_drgz46 · Answer

Don't know if it helps but there is a start of an answer here : https://confluence.atlassian.com/jirakb/how-to-restrict-customers-access-to-specific-projects-only-in-jira-service-management-917965224.html

Tommy McCullough · Answer

Service Desk Customers - these are users who may someday be given access to collaborate internally on your service desk project. For instance, this may be an employee within your organization that has access to other Atlassian products that should also be able to access your service desk using their logged-in user credentials.

Service Desk Customer - Portal Access - these are users that you will never have access to your internal site and truly only need portal access only. For example: if you were providing software support, these users would never access your service desk through federation with your site or project. They would only submit and interact with the service desk through the portal experience.

Zhuxin Wang · Answer

It can confirmer that "Service desk customer - portal access" should be used. Because I delete it in project permission, the system told me there have errors, permission should be updated and the customers can't login correctly.

Actually, I deeply agree with your questions.