Dialup ipsec, asigning ip from radius

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Hello,

I would like to use my 300D as some kind of ipsec concentrator.

It will be used for a lot of dialup connections. Every connection is authorised by configured radius server. Till now everything is ok and configurated (phase 2 is established). 

Next thing is to assign ip taken from radius, which is connected to customer's mac address in radius database.

Unfortunatelly i have no idea how to configure it. If i change anything phase 2 is falling down.

May i ask you to give me advice how to move it forward please?

It is my first post here, i couldn't find such problem using search mode :)