Re: [v6ops] Operational Implications of IPv6 Packets with Extension Headers

Fernando Gont <> Wed, 16 September 2020 09:43 UTC

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To: tom petch <>
Cc: IPv6 Operations <>
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From: Fernando Gont <>
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Date: Wed, 16 Sep 2020 05:40:41 -0300
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Subject: Re: [v6ops] Operational Implications of IPv6 Packets with Extension Headers
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Hi, Tom,

On 15/9/20 13:08, tom petch wrote:
> From: Fernando Gont <> Sent: 15 September 2020
> 12:24
> Hi, Tom,
> On 15/9/20 06:05, tom petch wrote: [...]
>> I wouldn't mind writing a Section that sits between the current
>> Sections 2 and 3 with more background on extension headers, if you
>> think that would be of value.
>> <tp> Yes please.  One page or two pages max, summarising why they
>> were thought a good idea, the different types and their uses, how
>> widely used they are  and with references;  RFC8200 may be
>> Normative but it takes a while to appear and that after RFC2460!

Ok.  I will craft text and send it to the list for review before
incorporating it.

> An intro to EHs -- and e.g., how the structure compares to the IPv4 
> packet structure is simply and doable. OTOH, what you suggest might
> now. :-)
> e.g.,Not sure one can tell how widely used they are. Also, getting
> into enumerating EHs will result in the relevant section becoming
> stale soon, since there seems to be quite a bit of development in
> this area.
> <tp> My sense is of the middle part of the I-D, the technical detail,
> is floating in mid-air, lacking an introduction, lacking a
> conclusion. and as such will only convince those who are already
> convinced.

FWIW, at lesast from my pov, we don't really want to convince people (of
doing this or that), but rather want to document the reasons for which
people may drop packets with EHs. i.e. documenting that such packets may
be dropped for very valid rational reasons.

> I have to read between the lines to divine that there is a connection
> between fragmentation and EH, between length of packet header and EH,
> between security and EH and so on.  By not making the connection
> explicit, I think that you will lose your target audience.

Fair enough. I'm always keen to improving the document, so thanks for 
the suggestion!

Fernando Gont
SI6 Networks
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