North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: backbone routers' priority settings for ICMP & UDP
> Marc, I'd have to agree, ICMP is more for flow control than congestion > control. A source quench is to slow a fast machine from overrunning a slow > machine, not preventing all flows from going through one link. > > One (weak) metaphor is that traffic lights at an intersection are for flow > control, while the traffic lights to get onto the freeway (common here in > California) are for congestion control... Extremely weak metaphore, since a source quench indicates there weren't enough buffers available to send your packets. Now, if the freeway was full, and cars started dropping out of the space/time continuum, that'd be more like a source quench. ;-) The freeway would call your wife at home and say "sorry, but your husband didn't make it to work because the freeways were too full." If wife runs correct a correct TCP implementation, she would know to initiate "slow start" and would send out her husbands at a slower rate until she gets a feel for how bad the traffic is. > One then > wonders how well Win95 implements source quench, if at all. Which side of the implementation do you mean? as a client, or as a gateway? I suppose it doesn't really matter. Since source quenches are not supposed to be used on routers anymore, the expectation of receiving a source quench on a large network (like the Internet) is a bad one, so the TCP implementations have to implement congestion controls through other means anyhow. TCP/IP Illus. Vol. I by W. Richard Stevens has a pretty good explanation of what source quenches are. Dave -- Dave Siegel [email protected] Network Engineer [email protected] (alpha pager) (520)579-0450 (home office) http://www.rtd.com/~dsiegel/
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