[Cake] flow isolation for ISPs

[Pete Heist]

> On Apr 6, 2017, at 10:39 AM, David Lang <david at lang.hm> wrote:
> 
> On Thu, 6 Apr 2017, Pete Heist wrote:
> 
>> Suppose there is a cooperative ISP that has some members who access the network through a single device (like a router with NAT), while others use multiple devices and leave routing to the ISPs routers. (No need to suppose, actually.)
>> 
>> There’s fairness at the IP address level (currently with esfq, maybe soon with Cake), but it's not fair that members with multiple devices effectively get one hash bucket per device, so if you have more devices connected at once, you win. There is a table of member ID to a list of MAC addresses for the member, so if there could somehow be fairness based on that table and by MAC address, that could solve it, but I don’t see how it could be implemented.
> 
> well, if the congested link is not the last-mile link to a user, the right answer is probably to increase the capacity of the link, and fairness issues would be a temporary thing until the link was upgraded.
> 
> remember that the fairness is a means to an end, good reponsive service. As long as the result is responsive for all users, a bit of unfairness is acceptable.

It’s a good point, but for a non-profit cooperative WISP, each hardware upgrade/installation can be a decision. In some locations and times there’s congestion in the backhaul, in others not. So it’s not always practical in this case to solve it by adding more hardware…