Re: [GROW] WGLC: draft-ietf-grow-route-leak-problem-definition (ends: 8/24/2015 - Aug 24)

[David Farmer <[e-mail]>]

Thinking about this a bit, I prefer "hairpin turn" over "U-turn".  In my mind a "hairpin turn" is talking about a tight turn in a road and by necessity a tight turn for the traffic on the road, the road itself turns back on itself.  Where as a "U-turn" talks about a tight turn traffic makes on road, usually to reverse direction on the road or where only the traffic is turning back on itself.  Put another way, you can make a "U-turn" on a perfectly strait road, but you can't make a "hairpin turn" on a strait road.

In the Internet we have a different term for a "U-turn", we generally call that a "loopback".  Therefore I think "hairpin turn" is the most appropriate in this case, unless we really mean a "loopback".

Whichever term we use, it should be clearly defined, it should be obvious at this point there is no clear unambiguous common understanding to rely on here.

Thanks.

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> On Nov 1, 2015, at 07:02, George, Wes <[e-mail]> wrote:
> 
> I just went hunting for an instance of this in IETF land, and only found
> references related to two hosts talking to one another from behind the
> same NAT.
> So, I went hunting on the internet, and everywhere I saw an explanation,
> it was of the variant "going out the same interface it came in on" and
> used U-turn synonymously. I was unable to find a reference to a definition
> as I outlined below. That's not necessarily an issue but we may need to
> explain the term before we use it so that there is no confusion.
> 
> Thanks,
> 
> Wes
> 
> 
> On 10/31/15, 10:07 PM, "Sriram, Kotikalapudi"
> <[e-mail]> wrote:
> 
>> Wes,
>> 
>> Thanks, Wes, for taking another look.
>> And thanks for laying out some interesting (and entertaining) alternative
>> names
>> that  can to used instead of "U-Turn".
>> Like we discussed in the hallway this morning, it makes sense to use
>> "Hairpin Turn"
>> instead of "U-Turn", especially considering "Hairpin Turn" has been used
>> in the VPN context.
>> 
>> Sriram
>> 
>> 
>> ________________________________________
>> From: George, Wes <[e-mail]>
>> Sent: Friday, October 30, 2015 10:01 AM
>> To: Sriram, Kotikalapudi
>> Cc: [e-mail]; [e-mail] [e-mail];
>> [e-mail]
>> Subject: Re: [GROW] WGLC: draft-ietf-grow-route-leak-problem-definition
>> (ends: 8/24/2015 - Aug 24)
>> 
>> On 10/12/15, 11:40 PM, "Sriram, Kotikalapudi"
>> <[e-mail]> wrote:
>> 
>> 
>> Sriram, this is significantly improved. One substantial comment that I
>> still have with this version:
>> 
>>>> It is also unclear from the text exactly what you mean by U-Turn
>>>> (it's not going back the way it came, so actually hairpin might be a
>>>> better term),
>>>> so a few words to clarify might be useful.
>>> 
>>> Hairpin seems to have a connotation that the turn is tight/constricted.
>>> So now I use the phrase “U-shaped turn” instead of “U-turn”.
>> 
>> WG] This may be nitpicking, but I don't think that adding "shaped" is
>> actually much of an improvement. I was thinking of hairpin from the way
>> that it is used in VPNs, as in data that enters and leaves the network via
>> the same edge device, but typically on a different physical or logical
>> interface (instead of entering on one PE and leaving via another), rather
>> than the way that it is used on racetracks to describe a near 180 degree
>> turn.
>> Here are a few ideas I had of other ways to refer to this:
>> 
>> -  a "detour leak", in that traffic will be detouring through the leaking
>> ASN
>> -  "ASN-in-the-middle leak" - similar to MiTM such that invoking the
>> concept is useful, but it's necessary to disambiguate the two since the
>> latter has a specific and well-known meaning
>> -  "parrotting leak" or "game of telephone leak" in that it is repeating
>> something it learned elsewhere, but introducing a mistake, not unlike the
>> grade school game of telephone (if you're up for a reference to The
>> Simpsons, you could call it a "purple monkey dishwasher leak" but that
>> would likely require too much explanation ;-) )
>> -  "[accidental | unintentional] transit leak" since the net result of the
>> leak is that traffic will transit the leaking AS rather than its normal
>> path
>> 
>> 
>> Thanks,
>> 
>> Wes
>> 
>> 
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