How Does PfR Work?

How does PfR Work?

Classic routing protocols generally chose the shortest path to the destination. Unfortunately, the shortest path is not always the best performing path. Also, classic routing approaches do not incorporate traffic class needs.

PfR works by 'observing' and then controlling network traffic. PfR measures the performance of traffic classes through the use of NetFlow and IPSLA, two Cisco technologies that are already embedded in the Cisco IOS.

PfR itself activates and manages these NetFlow and IPSLA configurations. Through monitoring, PfR learns the network's performance across multiple measurements:

Delay Packet loss Reachability Throughput Jitter MOS(mean opinion score) Link usage

If links' cost parameters are entered, PfR can also be set up to minimize bandwidth expense. By applying policies to traffic classes, operators can optimize network behaviour.

PfR works through existing network components: the border router and the master controller.

Border routers are any Cisco device that supports the PfR IOS which is connected to a WAN link.

The master controller is purely a software element within Cisco's PfR IOS. PfR IOS is supported on a broad range of Cisco equipment. Each location must have at least one border router and master controller, which can be co-located on the same device for smaller installations. Larger locations with heavy traffic may require a separate router to act only as a master controller, engaging up to ten different border routers.