6.4.e Identify performance routing [PfR]

6.4.e [i] Basic load balancing

Cisco PfR is essentially application routing based on network performance. It automatically detects path degradation and responds to avoid continued degradation. In many cases for a multi-homed enterprise , the traffic on an initial path is routed through another egress path that can meet the application performance requirements. This routing is different from classic routing, because classic routing looks only at reachability and does not look into the required traffic service needs, such as low loss or low delay. In addition, Cisco PfR allows a multi-homed enterprise to use all available WAN or Internet links. It can track throughput, link usage, and link cost, and automatically determine the best load balancing to optimize throughput, load, and cost -and network operators define the

Cisco PfR policies that implement these adaptive routing techniques. Cisco PfR policies can be based on the following parameters:

● WAN out-bound performance (traffic exiting from an enterprise): Delay, loss, reachability, throughput, jitter, and MOS

● WAN in-bound performance (traffic arriving into an enterprise): Delay, loss, reachability, and throughput

● WAN and Internet path parameters: Reachability, throughput, load, and link usage cost

Cisco Performance Routing consists of two distinct elements: border routers and a master controller. The border routers connect enterprises to the WAN; the master controller is a software entity supported by Cisco IOS Software on a router platform . Border routers gather traffic and path information and send this information to a master controller, which places all received information into a database. The master controller is configured with the requested service policies, so it is aware of everything that happens at the network edge and can automatically detect and take action when certain parameters are out-of-policy (OOP). Delay, jitter, and packet loss are used to determine the best exit path by the PfR engine.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 6265-6266).  . Kindle Edition.