Cisco joins route-optimization crowd

You may recall discussions in past issues of this newsletter about route-optimization, or route-control, appliances. These stand-alone devices, available from companies such as Internap Network Services, Opnix and Route Science, are used in situations when you have sites that are dual- or multi-homed to two or more ISPs.

You may recall discussions in past issues of this newsletter about route-optimization, or route-control, appliances. These stand-alone devices, available from companies such as Internap Network Services, Opnix and Route Science, are used in situations when you have sites that are dual- or multi-homed to two or more ISPs. 

The purpose is to dynamically choose the optimum ISP connection based on performance variables other than just the shortest path – typically the only criteria used by standard routing algorithms. Recently, Cisco hopped onto the route-optimization bandwagon, too, when it bundled such capabilities directly into its routers.

Typically, route-optimization appliances function as a Border Gateway Protocol (BGP) peer with your own Internet access router and your ISPs’ head-end routers, comparing data path performance end to end across all available paths before selecting a route.

Now Cisco routers collapse this functionality directly into its WAN access routers. Cisco routers running what the company calls the Optimized Edge Routing (OER) feature, available in Cisco IOS Software Release 12.3(8)T, can make real-time routing adjustments based on criteria other than shortest-hop criteria, too, possibly precluding the need to purchase a separate, stand-alone device for achieving this function.

Cisco routers consider traffic characteristics including latency, packet loss, link usage, reachability and throughput to choose the optimum path. This information is gathered by existing Cisco network management capabilities such as NetFlow accounting and Service Assurance Agent real-time performance monitoring – other features embedded in Cisco IOS. 

OER can perform route optimization for specific purposes such as minimizing costs or maintaining QoS for certain application traffic sensitive to metrics such as delay, according to the company.

For example, say you have a fixed-base and tiered-base cost structure on various links.  Depending on performance requirements, OER can reportedly route your call to whichever has the lowest-cost link available at that moment.