[e2e] Are we doing sliding window in the Internet?

Medhi, Deep DMedhi at umkc.edu
Sun Dec 31 14:50:59 PST 2006


John Heidemann, Katia Obraczka, and Joe Touch. "Modeling the Performance of HTTP Over Several Transport Protocols." ACM/IEEE Transactions on Networking, vol. 5, pp. 616-630, October, 1997. 

This covers maximum usable window size for different transmission media.

	-- Deep

> -----Original Message-----
> From: end2end-interest-bounces at postel.org 
> [mailto:end2end-interest-bounces at postel.org] On Behalf Of Detlef Bosau
> Sent: Sunday, December 31, 2006 1:16 PM
> To: end2end-interest at postel.org
> Cc: Daniel Minder; frank.duerr
> Subject: [e2e] Are we doing sliding window in the Internet?
> Happy New Year, Miss Sophy My Dear!
> (Although this sketch is in Englisch, it is hardly known 
> outside Germay to my knowledge.)
> I wonder whether we´re really doing sliding window in TCP 
> connections all the time or whether a number of connections 
> have congestion windows of only one segment, i.e. behave like 
> stop´n wait in reality.
> When I assume an  Ethernet like MTU, i.e. 1500 byte = 12000 
> bit, and 10 ms RTT the throughput is roughly 12000 bit / 10 
> ms = 1.2 Mbps.
>  From this I would expect that in quite a few cases a TCP 
> connection will have a congestion window of 1 MSS or even less.
> In addition, some weeks ago I read a paper, I don´t remember 
> were, that we should reconsider and perhaps resize our MTUs 
> to larger values for networks with large bandwidth. The 
> rationale was simply as follows: The MTU size is always a 
> tradeoff between overhead and jitter. From Ethernet we know 
> that we can accept a maximum packet duration of 12000 bit / (10
> Mbps) = 1.2 ms  and the resultig jitter. For Gigabit Ethernet 
> a maximum packet duration of 1.2 ms would result in a MTU 
> size of 1500 kbyte = 1.5 Mbyte.
> If so, we would see "stop´n wait like" connections much more 
> frequently than today.
> Is this view correct?

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