(usagi-users 00072) problem in setting a tunnel

["Roberto Canonico" <roberto.canonico@xxxxxxxx>]

Hi all,
I have installed the USAGI STABLE rpm files on a RedHat 7 Linux box.
The installation was ok.
Now I am trying to configure the box...
I want to setup a tunnel to Freenet6. 
I have been assigned the address: 3ffe:b00:c18:1fff:0:0:0:86d 
So I am doing:

ifconfig sit0 up
ifconfig eth0 add 3ffe:b00:c18:1fff:0:0:0:86d
ifconfig sit0 tunnel ::206.123.31.102
ifconfig sit1 up
route -A inet6 add ::0/ gw fe80::206.123.31.102 dev sit1

Unfortunately, the process fails at the third step:

[root@mauthe /root]# ifconfig sit0 tunnel ::206.123.31.102
SIOCSIFDSTADDR: No buffer space available

After the first two steps, ifconfig says:
[root@mauthe /root]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:40:95:41:04:46
          inet addr:148.88.153.199  Bcast:148.88.255.255  Mask:255.255.0.0
          inet6 addr: fe80::240:95ff:fe41:446/10 Scope:Link
          inet6 addr: 2001:630:80:8000:240:95ff:fe41:446/64 Scope:Global
          inet6 addr: 3ffe:b00:c18:1fff::86d/0 Scope:Global
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:84422 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1536 errors:0 dropped:0 overruns:0 carrier:0
          collisions:12 txqueuelen:100
          Interrupt:11 Base address:0xec00

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:3840  Metric:1
          RX packets:68 errors:0 dropped:0 overruns:0 frame:0
          TX packets:68 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

sit0      Link encap:IPv6-in-IPv4
          inet6 addr: ::127.0.0.1/96 Scope:Unknown
          inet6 addr: ::148.88.153.199/96 Scope:Compat
          UP RUNNING NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0

I would be happy to receive any clue to fix this problem...
Thanks,
    Roberto Canonico