ipv6 in ipv6 tunnel with FreeBSD 4.11

[Julien Abeillé]

Hi,
 
 I am using freebsd 4.11 and trying to setup ipv6 in ipv6 tunnels.
 I have the following testbed
 4 machines connected in line:
 
 M1-----------M2--------FreeBSD-------M3
    c::1---c::2  |  b::2----b::1   |   a::1---a::2
 
 I want to create a tunnel between FreeBSD (b::1) and M2 (b::2)
 
 Here is my configuration on the FreeBSD machine:
 em0 : a::1/64
 em1 b::1/64
 
 I do the folllowing to setup the tunnel:
 
 ifconfig gif0 create
 ifconfig gif0 tunnel b::1 b::2
 ifconfig gif0 d::1/64
 route add -inet6 -host c::1 -interface gif0
 
 I am not sure about what is the gif0 address d::1/64 used for.
 
 the problem is: when i ping or send any traffic from a::2 to c::1,
 the FreeBSD machine adds an ipv6 header with b::1 as source, b::2 as destination, but with hop count limit=0
 
 Is my configuration ok? 
 Thanks a lot,
 Julien