Understanding Application-Based Routing

The relentless growth of voice, data, and video traffic and applications traversing the network requires that networks recognize traffic types to effectively prioritize, segregate, and route traffic without compromising performance or availability. SRX Series Services Gateways support advanced policy-based routing (APBR), also known as application-based routing, to address these requirements.

APBR is a type of session-based, application-aware routing. This mechanism combines policy-based routing with an application-aware traffic management solution. APBR implies classifying flows based on the attributes of the applications and applying filters based on these attributes to redirect the traffic. The flow-classifying mechanism is based on packets representing the application in use.

APBR implements:

If a matching rule is found, the traffic is directed to an appropriate route and the corresponding interface or device.

APBR provides the following advantages:

APBR involves the following workflow:

FigureĀ 61 shows the sequence in which APBR techniques are applied.

Figure 61: APBR Flow Diagram

APBR Flow Diagram

The following procedure explains the application-based routing:

  1. APBR evaluates the packets based on incoming interface to determine whether the session is a candidate for application-based routing. If the traffic has not been flagged for application-based routing, it undergoes normal processing (non-APBR route).

  2. If the session needs application-based routing, APBR queries the application system cache (ASC) module to get the application attributes details (IP address, destination port, protocol type, and service).

    If the application is found, it is further processed for a matching rule in the APBR profile (see Step 3).

  3. APBR uses the application details to look for a matching rule in the APBR profile (application profile). If a matching rule is found, the traffic is redirected to the specified routing instance for route lookup.