I agree with Jouni that this is not an editorial change. 

In practice, TLS-based EAP methods are often built on the same code base.  That 
means that an EAP-TTLS implementation that also supports EAP-TLS will typically 
behave as specified in RFC 5281, disallowing use of the 'L' flag in fragments 
other than the first one. 

As a result, setting the 'L' flag in fragments other than the first one is 
probably not something that should be encouraged. 
 
-----Original Message-----
From: Sean Turner [mailto:[email protected]] 
Sent: Tuesday, November 16, 2010 9:24 AM
To: Pae, Min
Cc: Jouni Malinen; Dan Simon; Bernard Aboba; Ryan Hurst; [email protected]; 
[email protected]; [email protected]; [email protected]; 
[email protected]
Subject: Re: [Emu] [Editorial Errata Reported] RFC5216 (2510)

Did this ever get resolved?

spt

On 9/7/10 5:45 PM, Pae, Min wrote:
> I agree that the text I proposed does not take other TLS based methods into 
> account. The AAA vendor that we are working with does include the length in 
> fragments other than the first, but we are working with them to get this 
> addressed.
>
> I classified the errata as editorial because I didn't think the proposed text 
> redefines anything about the protocol. If your comment about restricting the 
> inclusion of the length field in fragments other than the first is included, 
> you are probably correct that this shouldn't be classified as editorial.
>
> On Sep 7, 2010, at 12:05 AM, Jouni Malinen<[email protected]>  wrote:
>
>> On Fri, Sep 3, 2010 at 11:51 PM, RFC Errata System
>> <[email protected]>  wrote:
>>> http://www.rfc-editor.org/errata_search.php?rfc=5216&eid=2510
>>
>>> Section: 3.1
>>
>> Please note that similar language exists in other places of the
>> document, too (2.1.5 and 3.2) and the same comments should apply to
>> them.
>>
>>> Original Text
>>> -------------
>>> The L bit (length included) is set to indicate the presence of the
>>> four-octet TLS Message Length field, and MUST be set for the first
>>> fragment of a fragmented TLS message or set of messages.
>>>
>>> Corrected Text
>>> --------------
>>> The L bit (length included) is set to indicate the presence of the
>>> four-octet TLS Message Length field, and MUST be set for the first
>>> fragment of a fragmented TLS message.  The L bit MAY be included
>>> in all fragments of a fragmented TLS message, but if included the
>>> TLS Length MUST represent the entire length of the TLS message.
>>
>> This would still leave some potential uses of the L bit undefined.
>> These two sentences cover only fragmented TLS messages. What about TLS
>> messages that are not fragmented?
>>
>> It should also be noted that the proposed text would make RFC 5216
>> (EAP-TLS) inconsistent with RFC 5281 (EAP-TTLS) as far as
>> fragmentation is concerned. I do not think that that would be a good
>> idea since it is possible to share same implementation for handling
>> fragmentation/reassembly of various TLS-based EAP methods (EAP-TLS,
>> EAP-TTLS, EAP-PEAP, EAP-FAST).
>>
>> RFC 5281 disallows use of the L bit in the fragments other than the
>> first one. In addition, it does actually cover the not fragmented
>> message case, too:
>>
>>    If there are multiple fragments, the first fragment MUST have the L
>>    bit set and include the length of the entire raw message prior to
>>    fragmentation.  Fragments other than the first MUST NOT have the L
>>    bit set.  Unfragmented messages MAY have the L bit set and include
>>    the length of the message (though this information is redundant).
>>
>> My preference would be for RFC 5216 to follow this design, but I don't
>> think I would be willing to call this change "editorial".. Are there
>> any known EAP-TLS implementations that actually use the L bit in
>> fragments other than the first one? Would that interoperate with other
>> EAP-TLS implementations?
>>
>> - Jouni
>

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