# Monitor Options for an Interface

An interface can monitor objects for one or more of the following events. Each of these events by itself or in combination can cause the state of the monitoring interface to change from up to down or from down to up:

- Physical disconnection/reconnection – All physical interfaces on a device monitor the state of their physical connection to other network devices (Layer 2 path monitoring). When an interface is connected to and has established a link with another network device, its state is physically up and all routes that use that interface are active.

- IP tracking failure/success – Layer 3 path monitoring, or IP tracking, sends ICMP requests on a specified interface to monitor up to four IP addresses at user-determined intervals and then checks to see if the targets respond. If the targets do not respond after a specified number of consecutive failed attempts, the device can deactivate the routes associated with the interface, even though the physical link still remains active. (The interface must remain active to continue its effort to elicit a response from its ICMP requests.)
  When the tracking of an IP address fails, the device compares the weight assigned to the tracked IP address with the failure threshold for tracked objects.
  If the failure threshold for tracked objects has been exceeded, the device then compares the weight for tracked objects with the monitored object failure threshold.
  If the monitored object failure threshold has been exceeded, the monitoring interface changes its state, usually from up to down. Optionally, you can also configure the monitoring interface to change its state from down to up.

- Failure/Success of a monitored interface – An interface can monitor the physical and logical state of one or more other interfaces and then take action based on observed changes. When a monitored interface changes state, the device compares the weight assigned to the monitored interface with the failure threshold for interface monitoring. If the failure threshold has been exceeded, the monitoring interface changes its state, usually from up to down. Optionally, you can configure the monitoring interface to change its state from down to up.

- Failure/Success of a monitored security zone – An interface can monitor all the interfaces in a security zone—in any security zone other than its own. For an entire security zone to fail, every interface bound to that zone must fail. As long as one interface bound to a monitored zone is up, the device considers the entire zone to be up. When a monitored zone changes state, the device compares the weight assigned to the monitored zone with the failure threshold.
  If the weight of the failed zone exceeds the failure threshold, the monitoring interface changes its state, usually from up to down. Optionally, you can also configure the monitoring interface to change its state from down to up.

On this page you can set global options that apply to IP tracking and to interface monitoring.

### To Set Monitor Options

1. Enter the necessary information:

Monitor Option

Enable Track IP: Click to enable the Track IP feature.

Monitor Threshold: Enter a value that, when exceeded, causes the monitoring interface to change its state from up to down, or from down to up.

Track IP Option

Threshold: Enter the cumulative total weight of all failed attempts to reach IP addresses on the interface that constitutes a tracked object failure on the interface. You can set the failover threshold at any value between 1 and 255. The default value is 3.

Weight: Enter a value that the tracked object failure contributes toward the monitored object failure threshold.

2. Click Apply to save your settings.

You can also link to the configuration pages to set the following monitored objects:

IP Tracking To add addresses for IP tracking, click Monitor Track IP ADD. Then configure the fields on the IP tracking configuration page. (See Track IP Configuration for an Interface.) After you add a tracked IP address, you can see its settings in the Track IP table. The Track IP table lists all configured tracked IP addresses and the following information about each one:
IP Address: Identifies the tracked IP address.
Interval (sec): Indicates the interval of time between ping requests.
Threshold: Indicates the number of consecutive failures to elicit a ping response from a specific IP address required to be considered a failed attempt.
Interface: Identifies the interface from which the ping request is sent.
Weight: Indicates the weight of the IP address.
Method: Indicates that the device uses ping requests to poll the remote device.
Configure: Click Edit to modify the existing Track IP entry, or click Remove to delete it from the system.

Interface Monitoring To enable interface monitoring for specific interfaces, click Monitor Interface Edit Interface. Then configure the fields on Interface Monitoring Configuration. After you finish, you see a table displaying each monitored interface and the weight that you assigned it.

Zone Monitoring To enable zone monitoring for specific zones, click Monitor Zone Edit zone. Then configure the fields on Zone Monitoring Configuration. After you finish, you see a table displaying each monitored zone and the weight that you assigned it.