Routing - Cisco Performance Routing (PfR)

Cisco Performance Routing (PfR) is a technology developed by Cisco to enhance traditional routing by making it more intelligent and dynamic. Instead of just basing routing decisions on static routes and IP prefixes, PfR takes into account the performance of the routes and can change paths based on a variety of criteria, including application requirements.

Here are some key concepts and benefits of Cisco PfR:

  1. Performance Metrics: PfR uses various performance metrics like delay, jitter, packet loss, and utilization to determine the best path for traffic.
  2. Dynamic Path Selection: Based on these metrics, PfR can dynamically adjust the path for certain types of traffic. For example, if one link becomes congested or starts experiencing high packet loss, PfR can redirect traffic to a better-performing link.
  3. Application Awareness: PfR can recognize specific types of application traffic (e.g., VoIP, video, or business applications) and can route them based on the specific performance requirements of those applications.
  4. Load Balancing: It can distribute traffic across multiple paths based on actual performance metrics rather than just simple round-robin or equal-cost methods.
  5. Link Health Monitoring: PfR continuously monitors the health and performance of links and can reroute traffic if a link degrades or fails.
  6. Cost Control: If an organization has multiple links with different cost structures (like a cheap internet link and an expensive MPLS link), PfR can make routing decisions that are cost-aware. For example, it might route less critical traffic over the cheaper link.
  7. Integration with traditional routing: PfR is not a replacement for traditional routing but rather an enhancement. It integrates with traditional IP routing to provide more intelligent path decisions.
  8. Components: PfR architecture usually consists of two main components:
    • Border Routers (BRs): These are routers at the edge of the PfR network that are responsible for implementing the path decisions.
    • Master Controller (MC): This is a central device (or a functionality in one of the routers) that makes the path decisions based on collected performance data.

To implement and use PfR effectively, it requires proper planning, configuration, and continuous monitoring. Proper thresholds for performance metrics must be set, and traffic classes need to be defined based on business and application requirements.