Posts Tagged ‘optimized edge routing’

Nov
01

This blog post is the first in a series covering Performance Routing (PfR) formerly known as Optimized Edge Routing (OER) that I will be publishing over the coming weeks.  I decided to cover PfR in a series of blog posts contrary to a single post as PfR is a very powerful and useful feature that leverages the power of Cisco’s IOS but at the same time PfR is potentially very complicated and often confusing feature to configure and troubleshoot.  Trying to cover PfR in a single blog post would be the equivalent of trying to cover OSPF in a single blog post.  In fact if you compare the IOS 12.4T OSPF Configuration Guide against the Optimized Edge Routing (OER) Configuration Guide you will notice that OER documentation is nearly 35% larger.

NOTE
In this blog post the term PfR will be used in place of OER wherever possible as Cisco has started to depricate the OER terminology and commands as of IOS 15.0.

The primary focus of these blog posts will be how PfR relates to the Routing and Switching CCIE Lab Exam (PfR v2.2).  The first couple posts will cover basic scenarios (static routing and BGP) with PfR, while introducing the reader to the PfR specific terminology and features as we use then and/or run across them. After we cover the basic scenarios I will get into more complicated scenarios using PfR to optimize routing based upon DSCP values, inbound routing optimization using BGP, routing based upon application response time and voice call quality. A final post will cover PfR in IOS 15.1 (PfR v3.0) and will focus on some of the newer PfR features. I will try to keep the details and complexities of PfR out of the first couple blog posts so that the reader can gain a solid grasp of PfR before moving forward.  I spend roughly half a day in my new Routing and Switching CCIE 10 Day Bootcamp covering PfR as it’s important for the R&S CCIE candidate has a solid understanding before attempting the CCIE Lab exam. Additionally, I personally believe that in the future the concept of centralized route control and/or route manipulation as with PfR could become more common, similar to the concept of OpenFlow. With that being said lets get started.

Performance Routing (PfR), previously called Optimized Edge Routing (OER), introduces a new concept into IP routing. With traditional routing, path selection decisions do not consider a particular path’s traffic characteristics be it throughput, actual delay, packet loss, voice mean opinion score (MOS), monetary cost of a given path, or jitter. PfR enhances the classic destination-based routing concept centered on the shortest path (lowest-cost metric) by adding into the routing selection process, network performance and/or application performance aware intelligence.  In the past when routing protocols were implemented in large-scale networks, routers did not have the resources to calculate the best path based upon anything other than a simple metric. Additionally, many of these networks would be considered simplistic in regard to the number of primary and redundant links compared to today’s networks. With the increase in CPU power and memory available in routers today, routing based solely upon a simple metric (hop count, cost, as-path length, etc.) is not the best use of these available resources. PfR will leverage these available resources to allow routing decisions based upon additional factors namely the networks performance and/or application performance across the network.  Getting the most out of your network’s available bandwidth and/or the best possible performance for your applications across the network should be one of the primary goals of any network implementation. Let’s look at an example of how we can do this using PfR.
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