RE: IPv4 flag day

Gary Sparkes via NANOG <[email protected]> Fri, 19 Jun 2026 15:00:51 +0000
Newsgroups gmane.org.operators.nanog
Message-ID <BN8PR10MB318553AA294A184634889805D5E22@BN8PR10MB3185.namprd10.prod.outlook.com>
I can't think of any reason to block any of these (dest unreach, echo req/rep, timeout exceed, or pkt too large) 


-----Original Message-----
From: Marco Moock via NANOG <[email protected]> 
Sent: Friday, June 19, 2026 10:36 AM
To: [email protected]
Cc: Marco Moock <[email protected]>
Subject: Re: IPv4 flag day

Am 19.06.26 um 05:30 schrieb Gary Sparkes via NANOG:
> For ICMP, we really only need timeout exceeded and echo request/reply, packet too large isn't required (and that's what breaks PMTU) nor is dest unreach.

Are there any reason to block ICMP dest unreachable?

I never saw one.

Breaking PMTU is a PITA - for both IPv6 and IPv4.

--
Gruß
Marco

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