To configure path selection, you define path selection rules to direct any application to any site.

Path Selection rules direct matching traffic onto specific uplinks. Traffic is matched by a combination of application and destination site.

You can create multiple rules for a site. When multiple rules are created for a site, the rules are followed in the order in which they are shown in the Path Selection page and only the first matching rule is applied to the site.

The network topology definition includes direct uplinks on an Edge. An Edge uses a direct uplink to steer packets to a specific gateway. The Edge can reach the gateway over Layer 2, so it can send packets directly to that gateway.

You configure a direct uplink using an Edge in-path IP address and a gateway IP address pair. For details, see Defining a hybrid network topology. When you define path selection rules, you specify the uplink preferences for certain traffic.

You must deploy two appliances using path solution to enforce the return uplink. To define the return uplink for traffic and override the original traffic uplink, you must deploy an appliance near the return traffic WAN junction point.

Define your remote sites, associated subnets, uplinks for the local site, the gateway IP address, and peer IP address in the Sites & Network page. You don’t need to configure uplinks for the remote and default site.

Select Enable Path Selection. Path Selection is disabled by default. Under Path Selection Rules, click + Add a Rule.

Identify the traffic flow by selecting an application for the Riverbed Application Flow Engine (AFE). Type the first few letters of the application in the Application/Application Group field. As you type the name of an application, a menu appears and lists available applications that match your typing. Select an application from the list. The default setting is any application or application group.

Select a destination site from the drop-down list. The default setting is any destination site.

The Any setting combines identifications of all known configured sites, including the Default-Site. Rather than configuring a separate identical path selection rule for every known site, select the Any setting to match the destination address of every configured site. When you select Any, path selection steers the configured application and any matching configured site, or the default-site, onto the selected uplink. Using the Any setting reduces the configuration steps required, yet provides a common application steering design.

Select the preferred uplink for the application. You can associate up to three uplinks per traffic flow in order of priority: a primary, a secondary, and a tertiary uplink. The uplinks you select cascade from one to the next, based on availability.

Select an outbound DSCP marking from the drop-down list. You must select DSCP values if the service providers are applying QoS metrics based on DSCP marking and each provider is using a different type of metric.

Optionally, select the default action to take if all the uplinks specified in the rule are down. These settings are available even when no uplinks are selected:

Sends the traffic unmodified out of the WAN side of whichever in-path it came in on. This is the default setting.

Drops the packets in case of failure of all three (primary, secondary, tertiary) paths. Select this option when you do not want the traffic to pass on any of the uplinks specified in the rule, not just the primary.

You do not have to define default uplinks to drop specific traffic flows; however, you must enable path selection.

The default rule matches any application to any destination that does not match another rule.

In QoS, you can define up to three uplinks for a rule and three DSCP values for a site. The DSCP values can steer traffic based on PBR in an upstream router.

You don’t need to restart the appliance to enable path selection. At this point, path selection is enabled. Path selection processes new flows after you enable it, but it does not process preexisting flows.

If the primary uplink assigned to a connection becomes unavailable, the appliance directs traffic through the next available uplink and triggers the Path Selection Path Down alarm. When the original uplink comes back up, the appliance redirects the traffic back to it.