Re: [Int-area] Alissa Cooper's Discuss on draft-ietf-intarea-frag-fragile-15: (with DISCUSS and COMMENT)

[Fernando Gont <[e-mail]>]

Tom,

On 7/8/19 04:50, Tom Herbert wrote:
> On Tue, Aug 6, 2019 at 6:17 PM Fernando Gont <[e-mail]> wrote:
>>
>> Hello, Alissa,
>>
>> Thanks for your comments! Inline...
>>
>> On 6/8/19 23:30, Alissa Cooper via Datatracker wrote:
>>>
>>> ----------------------------------------------------------------------
>>> DISCUSS:
>>> ----------------------------------------------------------------------
>>>
>>> Thanks for writing this document.
>>>
>>> Section 6.1 says:
>>>
>>> "Developers MAY develop new protocols or applications that rely on IP
>>>    fragmentation if the protocol or application is to be run only in
>>>    environments where IP fragmentation is known to be supported."
>>>
>>> I'm wondering if there should be a bit more nuance here to make the
>>> recommendation clearer. Do we think there is a case where an application
>>> protocol developed in the IETF will be known to only run in environments where
>>> fragmentation is supported? If we don't think developing such a protocol would
>>> be in scope for the IETF, then I'm wondering if that case should be called out
>>> explicitly with a stronger normative requirement.
>>
>> An application (developed in the IETF or elsewhere) might be used in
>> some controlled domain, where fragmentation may be known to be
>> supported. The message here is "unless you really know what you are
>> doing and you're in e.g. a controlled environment where fragmentation is
>> to be supported, you shouldn't rely on fragmentation".
>>
> Fernando,
> 
> There were several examples given of protocols in use in controlled
> environments that use fragmentation and justify that message. In
> particular, it is used in some cases of network layer encapsulation.
> For instance, consider that a packet entering an SRV6 domain may be
> encapsulated with hundreds of bytes of overhead. 

Isn't this the same thing I noted? i.e., you might have apps using
fragmentation in controlled domains. OTOH, if you expect to use it on
the public Internet, it is not reliable.


-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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