gre encap destination = point-to-point destination

On Sat, Nov 04, 2006 at 12:33:46AM -0600, David Young wrote:
> I am trying to understand why one would configure a
gre/gif tunnel
> with encapsulation destination equal to the
point-to-point destination.
> E.g., on this interface, the encap destination,
10.0.0.2, is the same
> as the point-to-point destination:
> 
> gre5006:
flags=d051<UP,POINTOPOINT,RUNNING,LINK0,MULTICAST> mtu
1476
>         tunnel inet 10.0.0.1 --> 10.0.0.2
>         inet 10.0.0.3 -> 10.0.0.2 netmask 0xffffffff
>         inet6 fe80::a00:20ff:fef9:60ee%gre5006 -> 
prefixlen 64 scopeid 0x112d
> [...]
> Can anybody explain, what is use such a configuration
as above?  Is there
> no other way to create a similar network?

Out of IPv4 addresses to assign to the target machine?

	-is