Hello Tobias,
On 09/02/2026 12:45, Tobias Fiebig wrote:
Hello Gorry,
On Sat, 2026-01-31 at 18:46 +0100, Gorry (erg) wrote:
There are a lot of changes and this is heading in a direction that
will resolve some (or all), I will comment and then expect a revision
so I can check where this has reached.
Thanks. I reply to your points inline; The new revision has just been
posted for review:
https://author-tools.ietf.org/iddiff?url1=draft-ietf-dnsop-3901bis-12&url2=draft-ietf-dnsop-3901bis-13&difftype=--html
Thank you ever so much. I have removed all items from your email that I
think are now addressed.
Please see a few answers and remaining points that it would be nice to tidy:
---
Clarified that this is about ICMP/ICMPv6.
Do you think that this needs informative references for ICMP/ICMPv6?
This additional REF is not needed by me.
-----------------------------
## Section 3.2: Impact of other headers (why “MAY)
"DNS servers MAY ensure that a total packet
size of 1280 octets is not exceeded by setting an MSS of
1220
octets."
(a) I suggest this wording does not present a requirement,
perhaps
the "MAY" ought to be lower case "may" or "can". (b) Please
explain
why how this avoids a size of 1280 octets? (To me, the total
packet
size includes any other extension or encapsulation headers, and
these
could result in a packet greater than 1280 octets.) What use-case
was
intended?
This again follows the same rational as with RFC9715 for UDP, but
translated to TCP.
GF: I agree, adding that explanation would be useful.
That explanation should be in there as well, now:
Please note that, for TCP, the resulting packet's size may be
further
enlarged by additional fields in the TCP header being in use, and
these
MSS values assume a minimal TCP header.
Is that correct? Or does MSS consider this?
The MSS does not consider the TCP header, see:
https://www.rfc-editor.org/rfc/rfc9293#name-maximum-segment-size-option
I think we might nearly agree: The MSS Option sets the packet size for
the remote sender, MS_S is the configured maximum size for a
transport-layer message that TCP may send. When there are any options,
The TCP packet size is effectively reduced by TCPhdrsize (the size of
the fixed TCP header and any IP or TCP options), as per Section 3.7.1.
<https://www.rfc-editor.org/rfc/rfc9293#section-3.7.1>
The new text says something I think could be confusing:
"Furthermore, to provide additional
clarity similar to the above guidance on UDP, DNS
servers MAY
ensure that a total packet size of 1280 octets is
not exceeded by
setting an MSS of 1220 octets, as suggested by the
[DNSFlagDay2020] initiative. Note that the
resulting packet's
size for TCP may be further enlarged by additional
fields in the
TCP header being in use [RFC9293], and these MSS
values assume a
minimal TCP header."
I suggest something more like:
"Furthermore, to provide additional
clarity similar to the above guidance on UDP, DNS
servers MAY
ensure that a total packet size of 1280 octets is
not exceeded by
setting the Sender MSS (MMS_S) to 1220 octets, as
suggested by the
[DNSFlagDay2020] initiative, see section 3.7.1 of
[RFC9293]. "
I added a reference to 9293.
Thanks, since this can be a difficult topic, I suggest we also include
the section number in the clarification (as above).
With best regards,
Tobias
There is also one new statement that I think could perhaps age, please
consider:
/While measurements have shown this to be/While measurements have shown
this to currently be/
Thanks again,
Gorry
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