What is URL based Local Breakout (LBO)?

Versa provides URL based Local Breakout (LBO) on predefined and user defined URL categories. It caches the URL categories along with the system application related info (For more information, refer to System Application Cache knowledge base article). This is possible only when the Versa DPI engine correctly identifies the first packet of the URL category associated with the session. 


NOTEThe URL category cache for SD-WAN and PBF is disabled by default. You must enable it explicitly to carryouta LBO.


Configuring URL Based LBO

Follow these steps to configure an SD-WAN rule to send all new traffic over URL Category LBO:

  1. Select Administration > Appliance and click on the appliance in the dashboard to navigate to the appliance context.
  2. In Appliance context, select Configuration > Services > SDWAN > Application Detection.
  3. Click Edit icon to modify the URL Category Cache. 

Defining URL Category Rule for SD-WAN Policy


Follow these steps to define a URL category rule for the SD-WAN policy.

  1. Select Administration > Appliance and click on the appliance in the dashboard to navigate to the appliance context.
  2. In Appliance context, select Configuration > Services > SDWAN > Policies. 

    • Select Policies tab and create a new SD-WAN policy named URL Based DIA.

    • Select Rules tab and click on the SD-WAN policy (URL based DIA) to configure the match criteria used to send all new traffic over the Local Breakout (LBO).

    • Select Source/Destination tab and click + in the Source Zone section.

    • Specify Intf-LAN-Zone to define the zone criteria used for sending traffic.

    • Select Application/URL tab and click + in the URL Categories section.

    • Specify news_and_media to define the URL category criteria used for sending traffic.

    • Select Enforce tab and enter the Nexthop IP address.

  3. Click OK to save the SD-WAN policy configuration.

    NOTE: Just like System Application Cache, URL cache entries also have an expiry.  An entry in the URL cache will timeout if it is not referenced in the last hour. The URL cache entry is refreshed when users initiate new sessions that match an URL cache entry. This prevents it from expiry. URL cache entries are purged when the Versa services restart. 


Viewing URL Cache Entires

Run the show pbf application-cache 1 CLI command to view the URL cache entries.

vsm-vcsn0> show pbf application-cache 1
ID   Vrf  Dst-Addr        Proto Dst-Port Hits     Age Application/URL Category
======================================================================================
0    8    10.40.23.12     6     80       5        0   App http (211)
0    8    10.40.23.12     6     80       5        0   App cnn (1522)
0    8    10.40.23.12     6     80       5        0   URL cat news_and_media (63)


Troubleshooting URL Category  Based LBO 

Check for these when a URL category based LBO does not work:

  • Ensure you have configured the rules under the correct policy and in the correct network (SD-WAN or PBF). 
  • Ensure the URL category caching is enabled. It is disabled by default.
  • Check the contents of the application cache to see if the URL category is present or not. If not, further debugging is required to determine whether the DPI engine detected the URL category or not.