I have received the following e-mail today: This is the tunnelrobot at SixXS, mailing you to inform you that your tunnel to NetCologne Gesellschaft fur Telekommunikation mbH has not been replying to pings for a period of time Here's the information regarding the tunnel: Handle : MI1652-RIPE PoP Name : decgn01 (de.netcologne [AS8422]) Your Location: Cologne, de SixXS IPv6 : 2001:4dd0:ff00:1a4::1/64 Your IPv6 : 2001:4dd0:ff00:1a4::2/64 SixXS IPv4 : 78.35.24.124 Your IPv4 : 212.44.167.50 Last known responding: 2012-02-06 13:05:16 The tunnel is however up and responding to ping requests from a machine in the UK: PING6(56=40+8+8 bytes) 2001:8b0:114:1::2 --> 2001:4dd0:ff00:1a4::2 16 bytes from 2001:4dd0:ff00:1a4::2, icmp_seq=0 hlim=55 time=43.278 ms 16 bytes from 2001:4dd0:ff00:1a4::2, icmp_seq=1 hlim=55 time=43.372 ms 16 bytes from 2001:4dd0:ff00:1a4::2, icmp_seq=2 hlim=55 time=44.146 ms 16 bytes from 2001:4dd0:ff00:1a4::2, icmp_seq=3 hlim=55 time=43.686 ms --- 2001:4dd0:ff00:1a4::2 ping6 statistics --- 4 packets transmitted, 4 packets received, 0.0% packet loss round-trip min/avg/max/std-dev = 43.278/43.620/44.146/0.391 ms I can also see successful ping requests from SixXS in "tcpdump": 01:39:27.293941 IP6 (hlim 64, next-header: ICMPv6 (58), length: 16) cl-421.cgn-01.de.sixxs.net > colwyn.zhadum.org.uk: [icmp6 sum ok] ICMP6, echo reply, length 16, seq 3 01:40:12.190738 IP6 (hlim 64, next-header: ICMPv6 (58), length: 988) gw-421.cgn-01.de.sixxs.net > cl-421.cgn-01.de.sixxs.net: [icmp6 sum ok] ICMP6, echo request, length 988, seq 25357 01:40:12.190834 IP6 (hlim 64, next-header: ICMPv6 (58), length: 988) cl-421.cgn-01.de.sixxs.net > gw-421.cgn-01.de.sixxs.net: [icmp6 sum ok] ICMP6, echo reply, length 988, seq 25357 Can you please investigate why the tunnel is reported as down? Thanks in advance