SixXS::Sunset 2017-06-06

Running multiple clients simultaneously on same AYIYA tunnel?
[de] Shadow Hawkins on Monday, 09 February 2015 22:49:01
Hi, recently I accidentially started two aiccu instances on two different client machines, with identical tunnel configuration. I would have expected that either the second client gets denied, or the first client gets kicked out. But to my surprise, it seemed to work!? Both clients got the same ipv6 address, even the same link local address, and both clients got working ipv6 connectivity. The clients are in completely separated ipv4 mobile networks. What happens here? It's a bit confusing... Cheers, Robert
Running multiple clients simultaneously on same AYIYA tunnel?
[ch] Jeroen Massar SixXS Staff on Tuesday, 10 February 2015 15:32:13
What happens here? It's a bit confusing...
It works because of luck. What happens is that the last packet received by the PoP is the endpoint that gets the next packets. Thus, host A sends a packet to the PoP and all inbound packets for that tunnel are send to host A. Then when host B sends a packet to the PoP all inbound packets come back to host B. Hence, as long as host A and B have some time between requests (typical on mobile platforms) everything is smooth. But even if they send packets quickly after each other, TCP retries will cause the endpoint selection to flip-flop so much that at one point the packet will arrive at the correct host. Thus while it "works" it is purely because AYIYA is a per-packet protocol. With a too high-frequency of flip-flops between addresses the PoP will kill the tunnel though, thus don't configure it that way, just use a second tunnel.
Running multiple clients simultaneously on same AYIYA tunnel?
[de] Shadow Hawkins on Tuesday, 10 February 2015 20:52:16
Thanks for the explanation! Funny, I had the same idea about how that might have "worked" today when we were playing with my 5 year old son's toy train... ;) Robert

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