[e2e] Does congestion control belong to The TransportLayer?

[David P. Reed]

At 01:30 AM 4/26/2004, Cannara wrote:
>Ethernet itself does congestion control on a LAN segment.  TCP does it above
>that.  NetBIOS/SMB/Samba do it above that.  Ethernet's congestion control acts
>at the micro- to milli-second scale.  TCP's is far slower, of necessity.
>Application level is slower still.  What most of us don't see is what goes on
>continually in metro boxes (ADMs...) and their chassis.  There various forms
>of control occur as well, also acting at very high speed, but obviously with
>larger RTDs than LANs, and smaller ones than continental nets.

Here I fail to see your point.  Encountering congestion is not controlling 
congestion.   Exactly how does Ethernet control congestion, for 
example?   As far as I can tell, it just arbitrates access to the medium 
(the switch fabric).

At best, some of these examples try to hide transient congestion, by 
introducing expandable buffering capacity.   But that just makes the 
inevitable result of congestion more catastrophic when it does happen.