Re: Non-Last Small IPv6 Fragments

[Fernando Gont <[e-mail]>]

On 14/1/19 12:18, Tom Herbert wrote:
>>
>> * a stateful operation for anotherwise stateless protocol
>>
> Fernando,
> 
> There is no fundamental problem with fragmentation. The core problem
> is that some intermediate nodes are processing headers and data beyond
> the IP and Hop-by-Hop options header.

If you need to reassemble fragments in the network, or at an end system,
and you're receiving packets at a very high data rate, you just cannot
keep up with fragments. that's the Inherent problem. Yo need to keep
packets in memory without even knowing whether they have been spoofed.



> That is non-conformant with
> RFC8200: "Extension headers (except for the Hop-by-Hop Options header)
> are not processed, inserted, or deleted by any node along a packet's
> delivery path". This becomes a material interoperability problem when
> intermediate nodes take invasive action, such as dropping packets or
> degrading the service, when they encounter protocols they don't
> understand. This problem applies not only to fragmentation, but also
> other extension headers, non-TCP transport protocols, and other
> protocols outside some narrow set of typically used protocols. To fix
> this, either non-conformant implementations should be changed to
> conform to the standard, or the standard should be changed to conform
> to the implementation.

Please look at draft-gont-v6ops-ipv6-ehs-packet-drops. There are
operational reasons for that. So, you need to look into the packet, but
you cannot do it in the fast path. Hence you just drop them.

Operators need to do their thing. And nobody is going to pay extra money
to do it on the past path -- even then, it would take time for all
current boxes to be phased out.

Your argument would be on the same line with my own regarding why there
shouldn't be any people under the line of poverty. -- that doesn't
change facts.


-- 
Fernando Gont
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