The path monitor service monitors the quality of network paths on a periodic basis.

A policy engine determines whether the resulting samples of a path monitor comply with the requirements of each associated policy, on a one-to-one basis. You can use the policy compliance results to influence PBR in the forwarding plane.

The path monitor service lets you configure one or more path monitor hosts. Each host determines the target to be monitored — the path endpoint — and the probe types it supports to measure path performance. Probe types include ping and twping.

The path monitor service also allows you to configure policies that define the required quality of a network path.

An instance of the path monitor service defines the association between a host and policy set. The instance runs in one of two mutually exclusive contexts — interface or routing. Context determines the monitored path:

• Interface: The monitor sends traffic to the destination by a route that egresses from the specified interface.
• Routing: The monitor sends traffic to the destination by any route in the routing table of the specified routing instance.