[ih] Origin of "best effort"

[Michael Greenwald]

Are we asking about the specific phrase "best effort"?
Or the notion that IP doesn't guarantee preserving
packet sequence, or even guarantee delivery?

I assume not the latter, because the Catenet paper said:

"It is very important to note that it is explicitly assumed that
datagrams are not necessarily kept in the same sequence on
exiting a network as when they entered.  Furthermore, it is
assumed that datagrams may be lost or even duplicated within the
network.  It is left up to higher level protocols in the catenet
model to recover from any problems these assumptions may
introduce."

And RFC791 restates this as:

"The internet protocol does not provide a reliable communication
facility.  There are no acknowledgments either end-to-end or
hop-by-hop.  There is no error control for data, only a header
checksum.  There are no retransmissions.  There is no flow control."

To my mind this explains what was later more loosely referred to
as "best effort".  Is there any reason to believe it was used as
a term of art, rather than a shorthand description of the 2 paragraphs
I quoted? (I know that when I first heard "best effort" I
interpreted it as a summary, but that just describes my reaction,
not the intent of whoever used it).

On 2017-01-19 11:09, Guy Almes wrote:
> Hi Brian,
>    This is actually an interesting question.
>    During the 1990s we had a discussion in which this phrase came up,
> used in the now-typical networking sense.
>    One colleague in the conversation, a lawyer, who had done work in 
> the
> construction industry, found the usage very odd because, he said, in
> contracts within that industry the phrase had a specific meaning and it
> obliged a person/company to a very very high standard of "best effort".
> In that context, for example, it might oblige a company to spend
> money/effort to a degree that would keep a promise but ruin any hope 
> for
> making money in the deal.  He noted that we computer engineers were
> using the term in an almost opposite (and, to him, an ironic) sense,
> viz., "do whatever is normal, but *not* heroic, and if it works, good
> and if it doesn't, don't worry about it".
> 
>    If the phrase is connected that older "contract language" usage, it
> would indeed be interesting to see how it came to have almost a 
> reversal
> or sense.
> 
> 	-- Guy
> 
> On 1/18/17 2:34 PM, Brian E Carpenter wrote:
>> I learnt very early on that the Internet offered a "best effort" 
>> service
>> for the delivery of datagrams.
>> 
>> Where did that meme come from, and when?
>> 
>> The earliest trace I found in a quick trawl was 1986 (RFC992). But 
>> RFC791
>> doesn't mention it, and defined TOS, such that all packets were *not* 
>> assumed
>> to be created equal. The 1984 Saltzer et al paper doesn't mention it 
>> either.
>> 
>> (RFC768 does say that UDP delivery is "not guaranteed" but that is not
>> the same thing as "best effort".)
>> 
>> The question is of interest because some analyses of network 
>> neutrality,
>> including a student dissertation I was reviewing yesterday, conflate 
>> the
>> end-to-end principle with best-effort packet delivery.
>> 
>> Regards
>>      Brian
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