Date: Mon, 30 Jul 2018 00:20:48 -0400 From: Kurt Lidl <lidl@pix.net> To: Maxim Konovalov <maxim.konovalov@gmail.com>, Michael Tuexen <Michael.Tuexen@macmic.franken.de> Cc: Randall Stewart <rrs@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r336465 - in head/sys/netinet: . tcp_stacks Message-ID: <91467128-5e84-6518-87ce-5374d410e1af@pix.net> In-Reply-To: <alpine.BSF.2.20.1807191616560.76318@mp2.macomnet.net> References: <201807182249.w6IMns6D076446@repo.freebsd.org> <alpine.BSF.2.20.1807191009050.76318@mp2.macomnet.net> <7FC7DAA2-9B03-4D89-A878-7706EDE4294A@macmic.franken.de> <alpine.BSF.2.20.1807191616560.76318@mp2.macomnet.net>
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On 7/19/18 9:18 AM, Maxim Konovalov wrote: > On Thu, 19 Jul 2018, 08:09-0400, Michael Tuexen wrote: > >>> On 19. Jul 2018, at 03:12, Maxim Konovalov <maxim.konovalov@gmail.com> wrote: >>> >>> Hi Randall, >>> >>> On Wed, 18 Jul 2018, 22:49-0000, Randall Stewart wrote: >>> >>>> Author: rrs >>>> Date: Wed Jul 18 22:49:53 2018 >>>> New Revision: 336465 >>>> URL: https://svnweb.freebsd.org/changeset/base/336465 >>>> >>>> Log: >>>> Bump the ICMP echo limits to match the RFC >>>> >>> [...] >>> >>> Just wonder, are there any practical reasons to do that? >> In case you send encapsulated packets triggering an ICMP message >> you actually need more than the 8 bytes which are currently >> reflected. > > OK, let me rephrase: why do you need more than 8 bytes? It looks like > it has been working rather well for 20+ years. Coming late to the game (I was away for vacation)... It's handy to have more than 8 bytes of returned payload for ICMP packets to allow for more sophisticated network health scanning metrics. Back when I worked at UUNET, we used the ICMP ECHO REQUEST packets to carry accurate timestamps for monitoring dispersion of multicast datagrams to select hosts. I know, ICMP ECHO REQUEST packets have required all payload to be returned since at least RFC 1712 - so it's not exactly the same as what is being change here... I imagine that a similar generic treatment of payload data for other ICMP type message might be handy too. -Kurt
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