Hello, please document the data size of ICMPv6 echo packets sent by PoPs in order to check whether the tunnel peer is alive, or alternatively document that the size is unspecified and is subject to change. I'm afraid I haven't found any information about it so far. The size apparently changed to 1028 bytes when the migration to SixXSd v4 was made, such that it did not pass my firewall rules which generally limits incoming ICMPv6 echo packets to 150 bytes. I solved it by accepting any ICPv6 echo packets coming from the PoP, but did not realize the problem until recently. A documentation entry about the change somewhere (e.g. in the News) would have been very helpful. Thanks, Christoph Schulz