Review: Jet Stream VDO-X
Servers
The VDO-X approach to servers is a bit different from other CDNs. Rather than having a few Windows Media servers, a few Flash Media servers, and various other servers, Jet Stream loads up server software for each of these on a single web server.
Figure 1. VDO-X server screen, showing clustering, ability to add a new media server, server type, and services available on each server
“Not only does this allow us to utilise a smaller pool of servers,” said van der Ziel, “many of which may sit idle in the traditional model, but it also allows us to include other server types, such as Darwin for QuickTime delivery, Wowza for Flash, StroboScope, and IceCast.”
What van der Ziel is referring to when he talks about the traditional CDN model is the idea of having a dedicated server at each point of presence (PoP) to handle only Windows Media, increasing to a cluster of Windows Media servers if demand increases. While this is a foolproof model that is necessary for large scalability, it often has a detrimental economic impact if that particular format is in lower demand.
Conversely, while Jet Stream loads server software on standard web servers, potentially keeping overall costs down, VDO-X doesn’t use virtualisation. As such, it still requires a higher number of servers than a virtualised solution, but it does guarantee that all services noted on a VDO-X CDN manager server are available for the CDN client.
Adding additional servers can be done on both a per-CDN/per-customer basis, as well as an intra-CDN basis, allowing Jet Stream to monitor the need for additional servers for its customers. Servers can be edge, core, overflow, or fallback and can also be clustered together, with the need for global load balancers. Servers can also be prepped but put in an inactive state so that they are ready to use at a moment’s notice, without requiring additional monthly recurring fees.
Networks
As I mentioned, the U.S. has only a few major locations (MAE East and West are the two best-known), which means that CDNs are trying to reach the majority of viewers. The U.S. model requires many more PoPs to accomplish what CDNs in Europe can accomplish relatively easily, thanks to the nature of European peering and a limited number of very large peering locations.
Figure 2. This is the VDO-X network operations centre screen. (Customer names have been blocked out.)
“The U.S. market, for instance, is much more segmented when it comes to points of presence,” said van der Ziel, “where a few key PoPs in Europe allow us to cover the majority of the market.”
One of these European locations sits in the Netherlands, near Amsterdam, meaning that Jet Stream’s European CDN solutions can ride atop a fast network.
“We're a CDN and streaming software developer so we outsourced the infrastructure to partners,” said van der Ziel. “We sit on top of a +2Tbps network—providing the benefit of performance without the need for deep pockets.”
This expanded network footprint is evident in the Networks section of VDO-X, which shows a variety of networks across Europe (mainly clustered in the Netherlands and the Benelux region) and the number of servers active on each network. This may not reflect the number of true servers available, as some servers may be inactive, as I noted before.
Related Articles
VideoExchange software from Jet-Stream will power the CDN's SmartCast services.
03 Jan 2011