Network Computing is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Analysis: Radiance's New CDN App Boosts File Delivery: Page 2 of 3

Radiance uses multiple IP sessions, several TCP windows and aggressive data-sending techniquest before acknowledgements return to speed up and bypass inefficiencies in TCP. These techniques don't follow the TCP specification-its window sizing and slow-start was designed to minimize network congestion. However, similar techniques have been used for years in competing traffic-optimization products from Expand Networks, Juniper Networks (formerly Peribit) and others. Radiance claims up 30 times faster file transfers in hostile networking environments compared with unmodified TCP/IP alone. On low latency and relatively clean networks, there may be no speed increase at all. However, in environments with many router hops, long physical distances (say, over international links), satellite connections and unreliable networks, the difference shows.

By comparison, in Network Computing's last WAFS review, Juniper Networks's WXC WAN Acceleration Appliance was able to deliver up to a 15x performance increase on real-world data when faced with 4 percent packet loss on a T1. Juniper also claims its product offers 30x acceleration, but that's an optimal figure, not real-world number.

In addition, you don't need to install a hardware device to take advantage of TrueDelivery, as you must do with WAFS. The service knows where the data is going and can intelligently route traffic through the fastest access point. This makes it an ideal acceleration technology for remote, roaming and small-office workers.

NWC Analysis

Overall, we're concerned with the ability of TrueDelivery to prioritize file transfers partly because the product is designed to optimize and saturate a connection. Radiance can deliver improved performance because it overcomes some of the inefficiencies in TCP/IP. By design, TCP will start slow and ramp up using bandwidth. This prevents TCP from monopolizing and congesting the network, but Radiance essentially removes this safeguard. This new version lets a user set priorities on his own file transfers. However, what's missing is the ability to say that user A's high-priority files are more important than user B's high-priority files, or that DNS traffic is more important than both those. WAN optimizers can use QoS (quality of service) techniques to control which priority, but can't act on a file-by-file basis. Radiance considers its solution complementary rather than competitive to WAFS, and is looking into partnerships with WAFS vendors.