IPv6 fragmentation weirdness

[Steve Bertrand]

Kevin Oberman wrote:

> Second, why the heck is the fragment going out first? This should be OK,
> but I suspect many firewalls (which are often not happy with fragments)
> are not likely to pass a fragment which precedes the initial frame.

I'll try to find some time today to see if I can replicate this issue.
I've never noticed it, mind you, I haven't been looking.

> Can anyone fetch anything from ftp.funet.fi via IPv6? I suspect it is
> something in the path that is blocking my traffic, so others may not see
> this, but I think the root issues is the kernel fragmenting packets way
> below MTU size.

7.2-RELEASE .iso @ ~14 Mbps from Ontario, Canada:

%traceroute6 ftp.funet.fi
traceroute6 to ftp.funet.fi (2001:708:10:9::20:1) from
2001:4978:1:600::2, 64 hops max, 12 byte packets
 1  unassigned.v6.your.org  18.742 ms  18.863 ms  18.967 ms
 2  ge2-47-107.ar1.ord1.us.nlayer.net  19.951 ms  19.985 ms  19.966 ms
 3  xe-1-3-0.cr1.ord1.us.nlayer.net  51.970 ms  70.543 ms  51.435 ms
 4  xe-4-1-0.cr1.nyc2.us.nlayer.net  87.404 ms  65.532 ms  63.924 ms
 5  xe-1-0-0.cr1.lhr1.uk.nlayer.net  135.912 ms  134.998 ms  134.890 ms
 6  2001:2000:3081:9::1  149.455 ms  150.032 ms  149.364 ms
 7  s-ipv6-b1-link.ipv6.telia.net  149.408 ms  149.922 ms  148.395 ms
 8  ldn-ipv6-b1-link.ipv6.telia.net  150.385 ms  148.909 ms  152.906 ms
 9  2001:2000:3080:d::2  225.358 ms  220.996 ms  217.359 ms
10  helsinki0-rtr.funet.fi  225.881 ms  234.301 ms  248.352 ms
11  csc0-x0000-helsinki0.ipv6.funet.fi  226.369 ms  226.393 ms  228.843 ms
12  ftp.funet.fi  225.370 ms  226.904 ms  229.846 ms

Steve


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