- Formally called as “Performance Routing” (PfR).
- Takes into account the performance statistics from the edge/border router and route dynamically based on statistics like bandwidth, delay, jitter etc.
- Can influence both incoming and outgoing traffic
- Master controller: (MC)
- Collects statistical information and uploads policy decision to border routers.
- Border Routers: (BR)
- Located at the edge of the network which collects and applies the policy from MC
- A router can act both as MC and BR at the same time.
- Profile Phase: Classifying the traffic to control .Can be automatic (via Netflow) or defined.
- Measure phase: BRs collect statistics and reports to MC. It can be either by Passive (interface stats, netflow) or active (IP SLA) method.
- Apply policy phase: Thresholds of performance value defined. MC uses this value and identify classes or links that are out of policy (OOP)
- Control Phase: MC can be configured to inject static routes or change metric
- Verify Phase: To make sure the changes has brought the network In policy.
- Identify an MC and configure key-chain. All messages between MC and BR will be encrypted.
- “oer master” command to enable MC.
- Configure border routers (using BR’s loopback IP) along with keychain. Also configure internal and external interfaces of that border router using “interface x/y [internal | external]”
- On the border routers, configure key-chain and enable “oer border” command.
- Configure local interface as loopback and the master IP address.
- “show oer master” / “show oer border”
- Profile phase:
- Configure MC to learn about traffic classes by either dynamic (netflow) or static.
- Traffic classes that are profiled are saved in Monitored traffic classes (MTC) table in MC.
- “learn” command to allow MC to use Netflow Top talker feature to identify prefixes that uses highest throughput or delay ( if “throughtput” and “delay” CLI are configured)
- Application traffic classes can be monitored using “protocol” command (NBAR)
- Prefix traffic classes can also be configured manually using “oer-map” and “policy-rules”
- Measure phase:
- BR monitor actively/passively about traffic classes. Also monitor the load/traffic loss on external links.
- Active probe: IP SLA (using “active-probe” command). Passive probe: Netflow.
- Traffic classes are mapped to one of the below states:
- Default: Traffic is not under OER control.
- Choose exit: OER is attempting to select an interface based on performance.
- Hold down: MC request one of the BRs to monitor the traffic class using active probes.
- In-Policy: Traffic is passed via an external link which satisfies default/configured policy.
- Out-of-Policy (OOP): No exits conform to policy. MC has to select best possible exit.
- Policy Phase:
- Threshold values can be defined globally or prefix-specific using oer-map
- Timers are used to avoid frequent change in exit-interface due to OER.
- Control Phase:
- Optional phase. OER changes the flow of traffic based on measurement.
- “mode route change” command on MC allows it to instruct BRs to control the routing.
- Changes are initiated when;
- Traffic class or exit interface goes OOP
- Periodic timers are expired and traffic classes are in “choose exit” state.
- Changes can be done using below options;
- IGP metric change, BGP attributes change, router injection or PBR introduction.
- Verify Phase:
- To check whether all traffic classes are brought In-policy.
- Netflow is used in verify phase.
<on MC>R0#show run | sec oer key chain oer key 1 key-string key1 oer master policy-rules cloud1 logging ! border 184.108.40.206 key-chain oer interface FastEthernet0/0 internal interface FastEthernet0/1 external interface FastEthernet1/0 external ! learn throughput delay protocol tcp mode route control mode route metric bgp local-pref 110 oer-map cloud1 10 match ip address prefix-list cloud1 set delay threshold 10000 R0#show oer master border Border Status UP/DOWN AuthFail 220.127.116.11 ACTIVE UP 00:10:16 0 R0#
<on BR>R1#show run | sec oer key chain oer key 1 key-string key1 oer border logging local Loopback0 master 10.1.1.1 key-chain oer R1#