PathControl Maps Best Egress Route

RouteScience device does BGP one better by conducting real-time checks of ISP performance.

RouteScience Technologies Inc.s PathControl optimizes traffic for multi-homed networks by using real-time performance statistics to improve routing decisions.

The PathControl device concentrates solely on egress routing (sending traffic to customers/users). In no way does it affect or improve the routing of inbound traffic, and there is no need for a device like this at sites that have only one ISP link. PathControl works well in an environment with only two outbound links, but it will be most useful and cost-effective at a site with four or even eight links, where more routing decisions need to be made.

eWeek Labs evaluated the PathControl 5008, which starts at $74,000. Prices increase as blade modules are added to the unit for more connectivity and for the addition of security modules to test and simulate Secure Sockets Layer traffic. The 5008 also can be leased for $5,550 per month.

PathControl, the only product of its kind that eWeek has seen, works in conjunction with BGP (Border Gateway Protocol), which allows routers within and among ISPs to share routing information. This maps efficient routes based on a number of factors, including topology.

For the most part, BGP does a fairly good job of picking the best route from a site to a destination. However, the bursty nature of IP traffic means the path to the logical BGP "winner" is not always the best route because dropped packets and resulting packet retransmissions can create large amounts of latency.

PathControl uses real-time performance statistics to change routes when the BGP winner has significantly higher latency than other available routes. To do this, PathControl acts as a BGP peer with edge routers (it does not replace or alter BGP) and advises against using the BGP winner when high latency is evident on that network link.

RouteSciences PathControl has the ability to create useful reports to quantify ISP billing and to also see how much performance can be improved using optimized routes.

We especially liked the fact that PathControl doesnt sit in the data path. As a result, a PathControl unit can be easily added to a network without becoming a bottleneck.

The PathControl device we evaluated uses a command-line interface for configuration, which will be familiar to network administrators who typically configure routers with Cisco Systems Inc.s Internetwork Operating System.

We found that the Web-based management and reporting tools in PathControl were easy to use and highly effective. Using these tools, we could easily see how a number of ISPs performed during a given time period to get a better understanding of why a BGP winner was ignored or avoided in certain cases.

To get a valid metric, PathControl calculates the amount of time it takes to establish a connection. For ISP connections that are more expensive compared with other links, network managers can add penalty points to the route score to prevent PathControl from moving too much traffic to those links.

PathControl can also be used for VPN (virtual private network) optimization. However, since PathControl can optimize only outbound traffic, network managers will have to install PathControl devices at the central site and remote sites to optimize VPN tunnels.

Senior Analyst Henry Baltazar can be reached at