A powerful partnership fights a real problem.

by Alex Goldman ISP-Planet Managing Editor [May 13, 2008]

Plymouth, Ind.-based ImageStream and Orem, Utah-based Powercode have been working together for about six months now (see ImageStream and Powercode Announce Partnership).

Since then, ImageStream has been working on "Per User Fair Queuing" (PUFQ) techniques to help ISPs manage bandwidth fairly.

Is this a particular problem for WISPs? "It is a problem especially for Wi-Fi wireless (there are other forms of wireless)," notes J.C. Utter, president of ImageStream. When a subscriber connects to an AP running 802.11g, they might get 54 Mbps to the AP and they might get one-tenth of that. But the upstream is unlikely to support the full access pseed of the radio. It might be 10 Mbps shared."

So if the subscriber opens a lot of connections at once, and then add many inbound at the same time, as a Bit Torrent client can, it can flood the AP. "That causes latency, and latency is the death of VoIP. It's a problem that's not specific to wireless but is a big problem in wireless networks (and in any other network with a fast connection to a slower pipe where the amount of bandwidth an indivudual user can access is a significant proportion of the total pipe)."

In theory, it would be simple to do this. "But the issue is how to do it on an ISP network offering tiered services. You want to not only recognize the service tiers but also ensure the delivery of VoIP and any other services."

PUFQ
So ImageStream is introducing Per User Fair Queuing (PUFQ). Each user gets what they paid for. Of course, in order to figure out what each user paid for, ImageStream's routers need to query to user database, hence the partnership with Powercode.

Utter says that Powercode, which was designed for WISPs, already has some nifty per-user management features. Combine that with some nifty features of the Linux 2.6 kernel such as diffserv and QoS and you have a powerful tool (look for a white paper later this year).

ImageStream has added deep packet inspection (DPI) to PUFQ to ensure that latency sensitive traffic doesn't get throttled. Utter thinks ISPs will prioritize VoIP and maybe games, but it's based on open source components, so a knowledgable ISP administrator will be able to prioritize anything they want.

So the ISP could offer priority access to YouTube? Yes, they could if they wanted to.

Because the technique simply tracks bandwidth usage and does not examine traffic, it is more efficient than DPI-based traffic shapers. Utter says the efficiency is the difference between a purpose built box and off-the-shelf hardware, a significant cost savings.

Furthermore, since the device is not analyzing the specific app, it will not prioiritize, for example, your ISP's VoIP over Vonage. That should please network neutrality advocates.

And since it doesn't collect per-user data, it doesn't violate user privacy the way some other solutions can.

But I think that the bottom line for ISPs—and especially WISPs—is that this solution is built for ISPs first, unlike so many other devices that are designed first for large corporations, with the needs of the ISP as an afterthought.

—End