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Date: Fri, 31 Aug 2018 09:44:17 +0200
From: Kurt Jaeger <pi@freebsd.org>
To: current@freebsd.org, net@freebsd.org, Kurt Jaeger <pi@freebsd.org>
Subject: Re: NFS via IPv6 between 11.2-REL amd64 and larger (>45 files)
 directories?
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Hi!

As Rick told me there's a ongoing debate on this, here's a copy
from my mail to stable@:

I've seen a strange effect: NFS via IPv6 between 11.2-REL amd64
boxes failed for directories with more than 45 files or directories.
Small directories worked. It seems to be an issue with
ipv6 fragmentation (?), as can be seen by tcpdump:

17:54:16.855978 IP6 nfs-serv > nfs-client frag (0|1448) 2049 > 709: NFS reply xid 1536109002 reply ok 1440 readdir
17:54:16.855979 IP6 nfs-serv > nfs-client frag (1448|36)

As soon as the NFS request is sent with fragments, it stalls.

Using TCP or IPv4 for the nfs mount works, UDP fails.

-- 
pi@FreeBSD.org         +49 171 3101372              2 years to go !