On 3/5/2013 10:40 AM, Spencer Dawkins wrote: > On 3/5/2013 8:15 AM, Brian E Carpenter wrote: >> On 05/03/2013 11:55, Dearlove, Christopher (UK) wrote: >>> I've no idea about the example quoted, but I can see some of their >>> motivation. >>> >>> TCP's assumptions (really simplified) that loss of packet = >>> congestion => backoff >>> aren't necessarily so in a wireless network, where packets can be >>> lost without >>> congestion. This means that TCP into, out of, or across, a MANET >>> using TCP can be >>> bad. It then tends to happen that the MANET people don't fully >>> understand TCP, >>> and the TCP people don't fully understand MANETs. >> >> The effects you mention were definitely discussed in PILC. >> http://www.ietf.org/wg/concluded/pilc.html >> Maybe the PILC documents need revision? >> >> Brian > > TRIGTRAN tried to nail this down in more detail after PILC concluded (I > co-chaired both PILC and the TRGTRAN BOFs). This quote from the IETF 56 > minutes pretty much captured where that ended up: > > <quote> > Spencer summarized a private conversation with Mark Allman as, "Gee, > maybe TCP does pretty well often times on its own. You may be able to > find cases where you could do better with notifications, but by the time > you make sure the response to a notification doesn't have undesirable > side effects in other cases, TCP doesn't look so bad" > </quote> > > If we had to have all the TCP responding-to-loss mechanisms in an > implementation anyway, and we could tell a sender to slow down, but not > to speed up, it wasn't clear that additional mechanisms would buy you much. > > References are at > http://www.ietf.org/proceedings/55/239.htm and > http://www.ietf.org/proceedings/56/251.htm > > The high order bit on this may have been that TRIGTRAN wasn't IETF-ready > and should have gone off to visit IRTF-land, but in the early 2000s, I > (at least) had no idea how to make that happen. >
Later on, there was also a proposed TERNLI BoF and mailing list, and bar BoF that resulted in: http://tools.ietf.org/id/draft-sarolahti-tsvwg-crosslayer-01.txt But didn't go any farther, that I'm aware of. Section 6 actually puts into context TRIGTRAN and other attempts to do something in this space. There's quite a bit of history just in the IETF. RFC 4907 (IAB's "Architectural Implications of Link Indications") is also a good snapshot of the thinking at that time. -- Wes Eddy MTI Systems
