commit 580ce9f083e5dec1c9b3aa49ef2e76ed30908b39 Author: Roger Dingledine arma@torproject.org Date: Tue Nov 6 17:30:42 2012 -0500

add a discussion section to the end of 213 --- proposals/213-remove-stream-sendmes.txt | 30 ++++++++++++++++++++++++++++++ 1 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/proposals/213-remove-stream-sendmes.txt b/proposals/213-remove-stream-sendmes.txt index d8d517d..f413876 100644 --- a/proposals/213-remove-stream-sendmes.txt +++ b/proposals/213-remove-stream-sendmes.txt @@ -120,3 +120,33 @@ Status: Open And since it's not super-urgent, I suggest we hold off on option two to see if option three makes sense.

+5. Discussion + + Based on feedback from Andreas Krey on tor-dev, I believe this proposal + is flawed, and should likely move to Status: Dead. + + Looking at it from the exit relay's perspective (which is where it matters + most, since most use of Tor is sending a little bit and receiving a lot): + when a create cell shows up to establish a circuit, that circuit is + allowed to send back at most 1000 cells. When a begin relay cell shows + up to ask that circuit to open a new stream, that stream is allowed to + send back at most 500 cells. + + Whenever the Tor client has received 100 cells on that circuit, she + immediately sends a circuit-level sendme back towards the exit, to let + it know to increment its "number of cells it's allowed to send on the + circuit" by 100. + + However, a stream-level sendme is only sent when both a) the Tor client + has received 50 cells on a particular stream, *and* b) the application + that initiated the stream is willing to accept more data. + + If we ripped out stream-level sendmes, then as you say, we'd have to + choose between "queue all the data for the stream, no matter how big it + gets" and "tell the whole circuit to shut up". + + I believe you have just poked a hole in the n23 ("defenestrator") design + as well: http://freehaven.net/anonbib/#pets2011-defenestrator + since it lacks any stream-level pushback for streams that are blocking + on writes. Nicely done! +