Cisco's OER (or Performance Routing as it is now called) is a routing method that can monitor exit links and pick the best path based upon multiple factors. The idea here is to monitor the utilization of an exit and move the traffic back and forth to keep it balanced (as much as possible). The configuration to go with our example config is as follows.
key chain key1
key 1
key-string border1
!
| The key chain is where the authentication between the Master controller and the border router is stored.
The "key-string <ENTER YOUR KEY> is the password. |
oer master
keepalive 1
!
| The OER master command initializes the OER master controller.
The keepalive is for the communication with the border router |
border 192.168.99.1 key-chain key1
interface FastEthernet0/1 external
interface FastEthernet1/0 external
interface FastEthernet0/0 internal | The border command under oer master configuration is where you will identify your interfaces as being internal or external. You will also identify the border router and password with this bit. |
!
learn
throughput
periodic-interval 5
prefixes 200
expire after time 120
| The learn section identifies what information you want the router to consider when monitoring the traffic. We specified throughput. Periodic interval is how often to watch the traffic. Prefixes is how many unique address to monitor. Expire after time is how long to hold the learned prefixes in the router memory. |
| backoff 180 200
mode route control
mode select-exit best
periodic 180
resolve range priority 1
resolve utilization priority 2 variance 15
no resolve delay unreachable relative 500 | The backoff timer is how long the router holds the route after it is no longer "in policy". Mode route control and mode select-exit best tells the router to modify the default route to push those prefixes to the best exit based upon resolve range and utilization. Unreachable relative is how many of those prefixes can be unreachable before the link is no longer utilized. |
!
oer border
local FastEthernet0/0
master 192.168.99.1 key-chain key1 | The OER border command initializes the border router. Local fastethernet 0/0 is the interface that will be used to communicate with the master controller and the next line identifies the master controller and its password. |
This is the minimum configuration to get the load sharing going. It can be ct and pasted without problems.
Next article is going to be fast failover out of the OER
Thanks for reading
Shawn