For greater route control, LiveNX Routing allows you to create policy-based routing (PBR) rules and apply these rules to your devices.
What is Policy-Based Routing?
Policy-based routing is used to change the path that a flow with a specific destination address takes out of the router. In the example below, the normal flow of VoIP traffic between the 2811 router and the 1841 router is shown:
In the following example, PBR will be applied to the 2811 router on the Fas0/0 interface, so that traffic flows through the VLAN 1 interface rather than Fa0/1. The flow will also enter the 1841 router from the VLAN 1 interface instead of Fa1. This can be visualized using NetFlow displays for the 2811 and 1841 routers.
NOTE: The policy is applied at the ingress interface of the receiving router.
Policy-Based Routing Monitoring Configuration
LiveNX allows easy monitoring and configuration of routes using visual route mapping. From the Routing menu, select Manage Policy-Based Routing to configure PBR.
For monitoring, the software reads the PBR policies directly from the devices and provides statistics for these policies. You can then use the LiveNX NetFlow module to troubleshoot PBR visually, using a flow-based view of the effects of PBR on application flows coupled with statistics on the PBR policies and underlying ACLs.
LiveNX also provides a complete PBR configuration solution in conjunction with its built-in ACL editor. Configuring PBR involves creating a route map consisting of a match to identify the incoming packets on a particular interface, and the set actions to perform on these packets.
Click Manage Policy Based Routing to create, edit, and apply PBR on a device.
Creating a Route Map
Click Add Route Map on the Manage Policy Based Routing dialog box to access the route map editor (Add/Edit Route Map). The top portion of the editor shows the series of entries, each entry consisting of match commands and set commands.
The match commands determine how to match the packets, and the set commands determine the actions to be performed. Match commands are typically created using a pre-defined ACL, which can be constructed using the LiveNX ACL editor.
Set commands determine how the packet will be treated once it is identified. PBR provides a rich set of actions to be performed, including altering the default routing behavior and changing ToS values. Multiple set commands can be added to perform multiple actions on the packets.
Click Preview CLI on the Manage Policy-Based Routing dialog box to view the commands before they are sent to the device.
Policy-Based Routing Workflow
The following is an example workflow for configuring, monitoring, and adjusting PBR-based actions:
- Create ACL for use with PBR.
- Create PBR to be used.
- Apply PBR to inbound interface.
- Observe PBR and ACL statistics for proper matches.
- Use Flow views to observe flow changes.
- Adjust PBR for proper operation.
Applying Policy-Based Routing
From the Manage Policy-Based Routing dialog box, click Apply Route Map to Interface to apply policies to multiple interfaces.
To see how the PBR policies are applied to interfaces, change Route Map to Interface in the upper left drop-down list on the Manage Policy-Based Routing dialog box.
Monitoring Policy-Based Routing
The route map statistics shown below will provide the number of packets and bytes that are hitting that particular policy map. These statistics can also be exported to a CSV file for further analysis.
- Select the device or interface to be monitored.
- On the Routing tab, click the Policy-Based Routing tab.
- Click Refresh to update the statistics.
- To save the statistics to a CSV file, click Export Route Map Statistics.
LiveNX Virtual Routing and Forwarding (VRF)
Virtual Routing and Forwarding (VRF) refers to a router’s capability to store more than one routing table, which separates traffic in each VRF from all other traffic and the Global routing table traffic. Thus, one physical router can serve as multiple routers, with all virtual routers’ traffic securely isolated in virtual realms. This feature is only available for Cisco devices. LiveNX allows you to visualize and list VRF routes by network device. Currently, LiveNX does not support PBR with VRF. View VRF data that LiveNX parses in the routing tables by selecting the VRF Name from the drop-down list in the Route Table toolbar. LiveNX automatically detects VRF tables.
NOTE: Select Global to display the non-VRF, “normal” routing table; and the visualization of the device, its interfaces, and their associated routes.
Select a VRF route table from the drop-down list on the Routing > Route Table tab in the device view. In this example, there is one mgmtVrf (VRF) tables and one Global (normal) table. LiveNX will display the selected routing table in the top pane, and a graphical route map in the bottom pane.