[ NNSquad ] Re: define: "service providers have to manage their networks somehow, especially during peak times."

[Wes Felter <wesley@felter.org>]

Colin May wrote:
> On 27 Mar 2008, at 20:30, Wes Felter wrote:

> > I like the idea of customers marking their traffic, but realistically 
> > customers would have to rely on their Linksys router to mark traffic 
> > for them, and right now the router doesn't do that. In the near term, 
> > ISPs are going to have to treat all traffic from a customer equally.
>
> Surely there is too much 
> chance of abuse from the people who are using the majority of bandwidth 
> to flag all their traffic up for preferential treatment?

It goes without saying that any QoS scheme must not be gameable by 
customers. Packet marking could be used to determine *which* packets are 
dropped, but not *how many*. For example, if an ISP needs to drop 1% of 
Alice's traffic, and 50% of her traffic is marked low priority, then 2% 
of the low-priority packets will be dropped and none of the 
high-priority packets will be dropped. If Bob marks all his traffic as 
high priority and the ISP needs to drop 1% of it, then the ISP will 
simply choose a random 1% to drop. In this case, it doesn't benefit Bob 
to mark all his traffic as high-priority.

In summary, two levels of QoS are required. The first level decides how 
much bandwidth each customer gets, and this decision is based only on 
how much the customer pays and the level of congestion. Within the 
allocated bandwidth there is another level of QoS which decides which 
packets to drop, and it is a good idea to allow customers to choose.

Wes Felter - wesley@felter.org