Hi, Sorry -- I've been on a plane most of the last day. The problem yesterday was detected & addressed; thanks for letting me know it's recurring. I am told that the problem has been isolated & working on a fix. Leslie. Iljitsch van Beijnum wrote: > On 5 mrt 2008, at 16:09, Leslie Daigle wrote: > >> As mentioned last week -- the wiki is now accessible: > >> http://wiki.tools.isoc.org/IETF71_IPv4_Outage > > Right, it was accessible yesterday, but not anymore, at least, for me: > the pages don't load. > > Looks like this is hosted on a 6to4 address. This isn't recommended, > because the quality of 6to4 reachability is highly variable. But > reachability doesn't seem to be the issue: > > $ ping6 -c 4 wiki.tools.isoc.org > PING6(56=40+8+8 bytes) 2001:720:410:1001:21b:63ff:fe92:9fbb --> > 2002:4e2f:6761::2 > > --- wiki.tools.isoc.org ping6 statistics --- > 4 packets transmitted, 4 packets received, 0% packet loss > round-trip min/avg/max = 133.693/133.840/134.106 ms > > So this looks like a path MTU discovery black hole. According to a > traceroute, the web server is terminating the 6to4 link itself and this > server is announcing a 1420 byte MSS: > > 10:54:54.464280 IP6 2002:4e2f:6761::2.http > > 2001:720:410:1001:21b:63ff:fe92:9fbb.49238: S 2106457901:2106457901(0) > ack 809912022 win 5632 <mss 1420,sackOK,timestamp 1184434509 > 542018613,nop,wscale 7> > > This is consistent with a 1500 byte IPv4 MTU - 20 bytes IPv4 > encapsulation = a 1480 byte IPv6 MTU. However, the server is unreachable > (from where I'm sitting) for 1480 byte packets: > > $ ping6 -c 4 -s 1432 wiki.tools.isoc.org > PING6(1480=40+8+1432 bytes) 2001:720:410:1001:21b:63ff:fe92:9fbb --> > 2002:4e2f:6761::2 > > --- wiki.tools.isoc.org ping6 statistics --- > 4 packets transmitted, 0 packets received, 100% packet loss > > Can this please be fixed? > > In general, people use a 1280 byte MTU for 6to4, which nicely avoids the > possibility of path MTU discovery black holes. > -- ------------------------------------------------------------------- "Reality: Yours to discover." -- ThinkingCat Leslie Daigle leslie@xxxxxxxxxxxxxxx ------------------------------------------------------------------- _______________________________________________ IETF mailing list IETF@xxxxxxxx https://www.ietf.org/mailman/listinfo/ietf