SixXS::Sunset 2017-06-06

Ticket ID: SIXXS #10686814
Ticket Status: User

PoP: nlhaa01 - Leaseweb B.V. (Haarlem)

intermittent failures to receive traffic (T114718)
[de] Shadow Hawkins on Sunday, 15 December 2013 12:35:27
Hi everyone! I have been trying to hunt down intermittent failures of T114718. The tunnel will work fine for long periods of time, then for other periods it will fail in a strange way. I have narrowed that down to the POP apparently only forwarding traffic to the endpoint when it is also receiving traffic from the tunnel. The tunnel endpoint does not run any packet filtering, and there should not be any filtering in place between the POP and the endpoint (which is also at Leaseweb but unable to have native IPv6). From what I can tell, the tunnel endpoint can generally receive unsolicited IPv4 traffic without restriction. Here is what I can show at the moment: I start by capturing IPv4 packets to/from the POP on the endpoint. I then run a ping6 to the endpoint from elsewhere and leave this running. This will show no replies at first. At this point, the packet capture shows no traffic to/from the POP. I then do a 1-packet ping6 of the POP from the endpoint. This will show the expected one outbound and one inbound packets on the tunnel. However, at this point the tunnel will -- for a brief period of time -- begin forwarding the ping6 traffic toward the endpoint that I started earlier. The ping6 will show a reply for the next two to three probes. After that, the POP will (apparently) stop forwarding packets into the tunnel again. IPv4 traffic between the POP and the endpoint goes quiet until I initiate some traffic from the endpoint again. This can be repeated. Also have pcap file. Thanks Stefan
intermittent failures to receive traffic (T114718)
[ch] Jeroen Massar SixXS Staff on Sunday, 15 December 2013 15:02:20
Without actual technical details, there is very little we can look at. It all just sounds like a connection tracker though. See the FAQ for the details. According to the live tunnel status your tunnel is also not responding to ICMPv6 Echo Requests requests, you should fix that.

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