Supported Object Tracking Options for Cisco IOS Policy-Based Routing

CDE.

Cisco IOS policy-based routing (PBR) allows you to control the path of traffic by configuring policies that determine the next hop based on specific criteria. PBR also supports object tracking, which enables you to track the state of objects and use that state to determine the next hop for traffic.

The following are the three object tracking options supported by Cisco IOS policy-based routing:

A. Absence of an entry in the routing table: With this option, PBR tracks the presence or absence of a particular route in the routing table. If the route is present, PBR uses the next hop specified in the policy. If the route is absent, PBR uses the next hop specified in the default route. This feature can be useful in scenarios where you want to redirect traffic if a particular route is down or unavailable.

C. Existence of an entry in the routing table: With this option, PBR tracks the presence of a particular route in the routing table. If the route is present, PBR uses the next hop specified in the policy. If the route is absent, PBR uses the next hop specified in the default route. This feature can be useful in scenarios where you want to redirect traffic based on the presence or absence of a particular route.

D. Results of an SAA operation: PBR can track the results of a Cisco IOS Service Assurance Agent (SAA) operation. SAA can be used to monitor network performance and track specific metrics such as packet loss, delay, and jitter. With this option, PBR can use the results of an SAA operation to determine the next hop for traffic. For example, if SAA detects that a particular link is experiencing high packet loss, PBR can redirect traffic to a different link.

The following options are not supported by Cisco IOS policy-based routing:

B. Existence of a CDP neighbor relationship: PBR does not support tracking the existence of a CDP neighbor relationship. Cisco Discovery Protocol (CDP) is a Layer 2 protocol used to discover information about neighboring devices. While CDP can be used to gather information about neighboring devices, it is not used to track the state of objects for PBR.

E. State of the line protocol of an interface: PBR does not support tracking the state of the line protocol of an interface. The line protocol is the state of the Layer 1 and Layer 2 protocols on an interface. While the state of the line protocol can be used to determine the availability of an interface, it is not used to track the state of objects for PBR.