---------- X-Sun-Data-Type: text X-Sun-Data-Description: text X-Sun-Data-Name: text X-Sun-Charset: us-ascii X-Sun-Content-Lines: 41 > From Tim.Farley@ATLHQ.XCELLENET.com Thu Aug 7 14:41:07 1997 > From: "Farley, Tim" > To: "'touch@ISI.EDU'" , > "'TCP over Satellite'" > > Subject: RE: Problematic Approaches > Date: Thu, 7 Aug 1997 17:45:04 -0400 > > [About HTTP 1.1, Joe Touch said:] > >> Not quite as much as planned. Although the connection is reused, > >> the window is not just be 'left open' in the meantime. > >> > >> When the source of data goes idle, some versions of TCP > >> slam the window shut (slow start restart after idle). > > Good point. But isn't this an implementation issue more than a protocol > design issue? I.e., the reason the source goes idle is because it > hasn't been given anything else to do yet, probably because the browser > is still parsing the HTML it just got in the initial GET of this TCP > connection. The gaps can be caused by parsing, or by waiting for the next user request. In either case the gap results in the protocol effectively needing to restart the window problem (which may have other solutions, e.g., use old values from this connection, rate pacing, use values from prior connections, etc.) > Perhaps we can make a recommendation here to HTTP 1.1 client > implementers. It would be: if you possibly can, parse the HTML of a > page as you get it, and issue the requests for the embedded graphics and > other links at the earliest possible opportunity. If done right, that > could keep the window from slamming shut. The problem is that the client asks for a page, then has to receive it before it can be parsed and subsequent requests pipelined. On high bw*delay nets, the window has to slam shut after the first request, which means there are objects of "first page", "sum of subsequent images", etc. There's still going to be a lot of window problems, since the objects are still smaller than the bw*delay (even when summed). 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