Multiple webdispatchers pointing on same instance

Hello Gurus,

Think I'm experiencing an issue about admin configuration in my developments.

I explain the situation.

SAP BW7.4 has parameter icm/host_name_full pointing on the local webdispatcher of the system.

But there is another webdispatcher installed on DMZ pointing on the same instance.

Here is my scenario and the problems occuring related to it.

I developed some webdynpro abap (WDA) on the system and these WDA are triggered with url related to DMZ webdispatcher. So users trigger this WDA pointing to DMZ webdispatcher. When they click on a button, it redirects to another WDA which switches on local webdispatcher... System asks them to log again as no cookie is found matching the local webdispatcher.

So here are my questions :

• Can we have multiple webdispatchers pointing on same instance ? What are the possible conflicts with ICM configuration and more precisely the configuration of variable icm/host_name_full ?
• What are the common configurations ? 1 Dispatcher for multiple instances for load balancing. So relation Web Dispatcher -> NW instances could be 1 : N ?
• Is relation NW instance -> Web Dispatcher 1:1 ?

Thanks for your dear help,

Christian