On Tue, 4 Sep 2007, Stephen Stuart wrote:
Operators are probably more interested in the "fairness" part of "congestion" than the "efficiency" part of "congestion."
TCP's idea of fairness is a bit weird. Shouldn't it be per-user, not per-flow?
How would you define "user" in that context?
Operators always define the "user" as the person paying the bill. One bill, one user.
It's easy to imagine a context where authentication at the application layer determines "user" in a bill-paying context. Passing that information into the OS, and having the OS try to schedule fairness based on competing applications' "guidance," seems like a level of complexity that adds little value over implementing fairness on a per-flow basis. In theory, any such notion of "user" is lost once the packet gets out on the wire - especially when user is determined by application-layer authentication, so I don't consider 802.1X or the like to be helpful in this instance.
Its fun to watch network engineers' heads explode.
What if the person paying the bill isn't party to either side of the TCP session? Stephen