[HECnet] Emulated XQ polling timer setting and data overrun

[Paul_Koning at Dell.com]

On Jun 5, 2014, at 3:24 PM, Johnny Billquist <bqt at softjar.se> wrote:

On 2014-06-05 21:12, Paul_Koning at Dell.com wrote:

...
True, provided congestion control is working.   In the days of DECnet Phase IV, congestion control was a topic of active research, rather than a well understood problem.   (Things like the TCP/IP    DEC bit    are an outcome of that work as well as a lot of other less obvious knowledge that made its way into other protocols.)   So in Phase IV, you probably don   t have effective congestion control, and scenarios with widely differing bandwidth points are likely to behave poorly.   In Phase V, that should all be much better.

I don't even know what the "DEC bit" in TCP/IP is. Never heard of it. (Feel free to educate me.)
But TCP have the slow start control, the ICMP source quench, handling of out of order packets, and I'm sure a few more tricks to better deal with this kind of situation.

It   s officially the    Congestion Experienced    bit.   http://minnie.tuhs.org/PhD/th/2Existing_Congestion_Contro.html has a large amount of stuff on the topic; section 4.2 mentions the DEC Bit.   In fact, that whole page is full of references to DECnet work on the subject.

	paul