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From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>
To: Pierre Dupond <76nemo76@gmx.ch>
Cc: Matthew Seaman <matthew@FreeBSD.org>,  freebsd-questions@freebsd.org
Subject: Re: ping6 www.freebsd.org hangs
References: <20190906192931.d5735e1602f98d6b9a2906c0@gmx.ch>
 <b710de87-756e-6e6f-654c-aa41e84b36e0@FreeBSD.org>
 <20190911122523.9b94cd45533279bf46592e94@gmx.ch>
Date: Wed, 11 Sep 2019 09:56:56 -0400
In-Reply-To: <20190911122523.9b94cd45533279bf46592e94@gmx.ch> (Pierre Dupond's
 message of "Wed, 11 Sep 2019 12:25:23 +0200")
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X-Spamd-Result: default: False [-1.03 / 15.00]; ARC_NA(0.00)[];
 NEURAL_HAM_MEDIUM(-0.76)[-0.762,0]; FROM_HAS_DN(0.00)[];
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 ASN(0.00)[asn:7922, ipnet:23.30.0.0/15, country:US];
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Pierre Dupond <76nemo76@gmx.ch> writes:

> Thanks for the tip. Finally I was able to reproduce the
> problem (which arise from time to time).
>
> The ping6 command failed either with the IPv6 address (or
> the name). The result is the same for an other address (like google)
> but at the same time I can reach these address from other machines.
>
> It is also possible to reach (with ping6) the external router of my organisation
> (passing few intermediate routers).
>
> What is curious however is that the command "traceroute6" succeed
> and then the command "ping6" works again.
>
> It sounds like a strange fragmentation problem.

By default traceroute uses UDP and ping uses ICMP.
Could be a stateful firewall somewhere.
You could test that by using ICMP with traceroute
if it happens again.