On 2011-12-24 18:34, Fernando Gont wrote:
> Hi, Florian,
>
> On 12/23/2011 07:46 AM, Florian Weimer wrote:
>>> That aside, I don't know whether e.g. NAT64 or the like used this
>>> (.e.g, whether they are used for transition technologies as envisioned
>>> in RFC 2460). However, it might also be the case that such "atomic
>>> fragments" are generated when communicating through networks that do
>>> not really have a MTU >= 1280. In such scenarios there might be some
>>> for of gateway that sends the ICMPv6 PTB advertising a Next-Hop MTU
>>> smaller than 1280, thus resulting in atomic fragments (such that it's
>>> easier for the "gateway" to fragment the IPv6 packets).
>> Yes, this seems a plausible explanation. I wouldn't consider this
>> actual use, rather network misconfiguration.
>
> Why?
MTU <1280 is a complete breach of the IPv6 standard, so it is by
definition a misconfiguration.
IPv6 requires that every link in the internet have an MTU of 1280
octets or greater. On any link that cannot convey a 1280-octet
packet in one piece, link-specific fragmentation and reassembly must
be provided at a layer below IPv6. [RFC 2460, sectioin 5].
Brian
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