Re: [Gen-art] Gen-ART Review of draft-ietf-bfd-base-08

Eric -

On May 7, 2008, at 1:26 PM, Eric Gray wrote:

> David,
>
> 	I agree with Spencer on the point of "system thoughts"
> verses "system states."  This may appear to be a style issue,
> but it is actually simply a matter of trying to be as precise
> as the language allows.  Who knows what a system "thinks"?
> But it should be clear if a system is in an appropriate state.
>

DW: Sorry, which comment is this in reference to?

> 	On the next issue, I don't understand your argument: are
> you saying that you believe it is necessary to explicitly say
> that "defending against operator error is out of scope"?
>

DW: Given we are talking about laws of physics and we have seen  
implementation and deployment issues, it seemed worthy of not  
removing the statement in this instance.

> 	Finally, Spencer's (last?) comment on use of "stronger"
> is (again) not a stylistic one, but an attempt to squeeze the
> little bit of precision that can be achieved in English.  It
> is apparent that you believe you are saying "Using SHA1 is
> believed to have stronger security properties than MD5" (as
> indeed is suggested by Spencer), but you are not (exactly).
> Change the statement to "drinking milk, as opposed to chewing
> rocks, leads to stonger bones" and you will see that what you
> have said makes no explicit comparison between SHA1 and MD5
> (or milk and rocks, in my example).  Because the statement is
> already in passive voice (whose belief is this?), and is vague
> enough as it is, then we should try to fix as much of it as we
> can.
>

DW: Finessing this sentence isn't an issue. Rocks for breakfast?

-DWard

> --
> Eric Gray
> Principal Engineer
> Ericsson
>
>> -----Original Message-----
>   --- [SNIP] ---
>>
>>>   packet to the correct BFD session after it is looped back to the
>>>   sender.  The contents are otherwise outside the scope of this
>>>   specification.
>>>
>>> 6.6. Demand Mode
>>>
>>>   Demand mode is requested independently in each direction by virtue
> of
>>>   a system setting the Demand (D) bit in its BFD Control packets.
> The
>>>   Demand bit can only be set if both systems think the session is
> up.
>>>
>>> Spencer (clarity): this doesn't seem quite right to me, because the
>
>>> statement requires that my system knows what the other system
>>> thinks. Is it correct to say "a system can only set the Demand bit
>>> when a session has transitioned to UP"? It might be preferable to
>>> delete the second sentence, because the following text explains
>>> this in greater detail, anyway.
>>>
>>
>> DW: This appears to be a style comment on "is up" vs "has
>> transitioned to UP," right?
>>
>>
>>>   The system receiving the Demand bit ceases the periodic
> transmission
>>>   of BFD Control packets.  If both systems are operating in Demand
>>>   mode, no periodic BFD Control packets will flow in either
> direction.
>>>
>>>   Note that this mechanism requires that the Detection Time
> negotiated
>>>   is greater than the round trip time between the two systems, or
> the
>>>   Poll mechanism will always fail.  Enforcement of this requirement
> is
>>>   outside the scope of this specification.
>>>
>>> Spencer (clarity): you're not describing a requirement, you're
>>> describing a constraint. Perhaps "Note that this mechanism will
>>> always fail unless the Detection Time negotiated is greater than
>>> the round trip time between the two systems", and drop the second
>>> sentence?
>>>
>>
>> DW: What we are trying to state is that BFD cannot keep an operator
>> from making a configuration error. There is a constraint due to
>> physics and a requirement that it be adhered to and ... BFD can't
>> stop anyone from doing something stupid. "Enforcing the requirement
>> to meet the constraint ..." may be clearer language although a nit.
>>
>   --- [SNIP] ---
>
>>>   transmission rate and/or the Detection Time).
>>>
>>> Security Considerations
>>>
>>>   Using SHA1 rather than MD5 is believed to have stronger security
>>>   properties.  All comments about MD5 in this section also apply to
>>>
>>> Spencer (clarity): "stronger than"? would this be correct if it
>>> said "Using SHA1 is believed to have stronger security properties
>>> than MD5"?
>>>
>>>   SHA1.
>>>
>>
>>
>> DW: This seems a style choice.
>>
>>
>> Many thanks for your thorough review.
>>
>> -DWard
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>>

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