-------- Original Message --------

> So, could someone explain what are Phase 1 and Phase 2 lifetime exactly 
> for?

I answer to myself ;-) hoping this could be useful to someone else...

I've found a very interesting article on IPsec on the ONLamp.com 
(O'Reilly) web site, written by Dru Lavigne.

The URL is: http://www.onlamp.com/lpt/a/3009

In particular, read the last paragraph: "Phase One and Phase Two".

-- Vincent