[vpn-help] Tunnels within tunnels?

[kevin shrew-vpn]

Hi everyone, just wondering if this is possible...

I've got a setup where I have a VPN to the border firewall (between the
Internet and my network).  I also have some special purpose VPNs
to firewalls inside my network.  The border VPN policy secures all
traffic to my network's IP space, including the IPs of the internal
firewalls.

If I first connect to the VPN that terminates at the border firewall,
would I then be able to initiate a VPN to the internal firewall?  

(Obviously it would travel through the existing tunnel, since the border
VPN policy includes the IP of the internal firewall.)

I'm just curious if this could work.  I could test it, of course, but
even if it doesn't work when I try, there's always the thought that "if
I just tweak one setting, it could work..."