CSZ

This paper provides a hypothetical solution to the real-time flow vs data flow issue. It suggests that real-time flows that need certain guarantees from the network can explicitly request these guarantees, and that using routers with WFQ implemented will achieve these guarantees. Similarly, in order to achieve a good quality of service for adaptable real-time applications (that only ask for best effort) will have a FIFO+ queue within the WFQ to address their needs. However, these applications must provide guarantees to the network that they will operate within certain bounds (by providing a rate and a bucket size). If multiple levels of service are desired (such as an extra level of service for datagrams), then multiple FIFO+ queues can be used within the WFQ.

The idea behind a FIFO+ queue is that a packet should not be adversely affected by many different sources. Therefore, any router that causes a packet to be delayed (more than the average delay time for packets of its priority) will mark the packet with the extra delay time. A router receiving that packet can then "pretend" to have received it earlier. This reduces the overall jitter that will be experienced by packets on long trips. As with most algorithms, I have trouble imagining a world in which a Tier 2 ISP would not take advantage of this by marking all of the packets from its own customers.

Once again, the most difficult part of this algorithm is the incentive. There must be some sort of incentive (other than being a good samaritan) for a user to declare their packets to be of the "lowest" priority. Once again, economic incentives are an option, except that nobody wants to pay money by the byte (just ask a Verizon Wireless Customer).

Overall, I think one of the most important things that this paper has done is to classify the different kinds of traffic that flow across the internet. There exists a distinction between a two-way video chat on Skype, a video being watched on YouTube, and a high resolution trailer for Starcraft 2 that's only available for download; this paper has done an excellent job of making these distinctions clear.