Intelligent route control improves BGP

Internet capacity has increased significantly in the past two years, but the explosive growth in Internet traffic has been accompanied by bottlenecks, especially in the "middle mile" of Internet-based networks.

These bottlenecks originate from a variety of sources and cause application performance to degrade even to the point of service failure.

Intelligent route control promises to let companies control Internet routing while reducing network costs, effectively eliminating middle-mile congestion.

To combat problems that can occur within a particular service provider's network, corporations increasingly are using multiple service providers to obtain failover and proximity to end-user browsers. While this "multihoming" approach avoids reliance on a single carrier, it also introduces considerable management complexity.

The only tool available to manage routing information has been Border Gateway Protocol (BGP). BGP lets different networks advertise "reachability" information to one another for specific prefixes, and this information is distributed to routers across the Internet so each router knows which prefixes are reachable through the networks to which it is connected.

To reap the redundancy benefits inherent in multihoming and minimize the complexities of using BGP, intelligent route control products continuously monitor performance at thousands of individual destination prefixes across multiple paths - regardless of the application - and optimize routing to these prefixes. These products also let organizations establish route optimization policies that take into account application performance parameters and bandwidth usage/cost constraints.

Intelligent route control products typically perform three functions: calibration, navigation and representation or reporting.

The calibration function continuously monitors traffic flows to identify destination networks applications are sending traffic to, and uses active and/or passive monitoring techniques to measure traffic performance to these destination networks and measure traffic performance to these networks across each ISP. The performance statistics are forwarded to the navigation function used in making route optimization decisions.

The navigation function uses statistics gathered during calibration to determine whether the user-defined performance (in terms of packet loss and latency) and transit cost policies are being met and makes route changes in near real time in accordance with these policies.

If it detects that performance to a specific destination over a low-cost provider has exceeded that destination's policy threshold, it examines alternate ISP links to find the least-cost path that meets both loss and latency performance requirements. The navigation function then redirects traffic over the new path, by issuing a standard BGP route update to customer routers. Route changes are forwarded to the representation function for historical reporting.

The representation function uses the statistics and routing change logs gathered during calibration and navigation to provide reports on bandwidth usage/cost, traffic delivery performance and route change activity. This function also is used to provide access to user management and configuration functions.

Companies that use intelligent route control experience three key benefits:

Johnson is chief architect at netVmg. He can be reached at jeremy@netvmg.com.

Route control picks most effective ISP
Network World Tech Update, 11/19/01.