Need more info on VS within GTM servers

Hello,

 

 

I'm using LTM and ASM a few years. Currently working on GTM and i've a question about that.

 

As I understand it correctly the Virtual Server Discovery functionality discovers the VS's within LTM's, so that you can create GTM pools where the members are the VS's of LTM's.

 

Currently I've disabled that functionality, because we are in a stage where the GTM will not reference LTM. So I create VS's manually. Why do I need to enter a service port for the VS within GTM? The help file doesn't mention anything about this and the manuals neither. In a LTM situation I understand the need. In a GTM situation I don't.

 

 

This is also the case in a iRule where the "host" function has an option to add the port as parameter, but why? For LTM it makes sense, but for GTM?

 

 

Hope someone has the answers to this.