The Application classification feature allows the NetScaler SD-WAN appliance to parse incoming traffic and classify them as belonging to a particular application or application family. This classification allows us to enhance the QoS of individual application or application families by creating and applying application rules.
You can filter traffic flows based on application, application family, or application object match-types and apply application rules to them. The application rules are similar to Internet Protocol (IP) rules. For information on IP rules see, How to Create Rules.
For every application rule, you can specify the mode of transmission. The following are the available transmit modes:
- Load Balance Path: Application traffic for the flow is balanced across multiple paths. Traffic is sent through the best path until that path is completely used. The remaining packets are sent through the next best path.
- Persistent Path: Application traffic remains on the same path until the path is no longer available.
- Duplicate Path: Application traffic is duplicated across multiple paths, increasing reliability.
The application rules are associated to classes. For information on classes, see How to Customize Classes.
By default, the following five pre-defined application rules are available for Citrix ICA applications:
In the SD-WAN network, when the incoming packets reach the SD-WAN appliance, the initial few packets do not undergo DPI classification. At this point, the IP rule attributes such as Class, TCP termination and so on are applied to the packets. After DPI classification, the application rule attributes such as Class, transmit mode and so on override the IP rule attributes.
The IP rules have more number of attributes as compared to the application rules. The application rule overrides only a few IP rule attributes, the rest of the IP rule attributes remain processed on the packets.
For example, consider you have specified an application rule for a webmail application such as Google Mail that uses the SMTP protocol. The IP rule set for SMTP protocol is applied initially before DPI classification. After parsing the packets and classifying it as belonging to Google Mail application, the application rule specified for the Google Mail application is applied.
To create application rules:
To confirm if application rules are applied to traffic flow, navigate to Monitoring > Flows.
Make a note of the app rule id and check if the class type and transmission mode are as per your rule configuration.
You can monitor the application QoS such as no of packets / bytes uploaded, downloaded, or dropped at each site by navigating to Monitoring > Statistics > Application QoS.
The Num parameter indicates the app rule id. Check for the app rule id obtained from the flow.