The Link Monitor object allows you to monitor a link for a specific interface and belongs to a link detection group.
A new Link Monitor is created for each interface that is configured for link verification. The Link Monitor is provided with a destination to use for link verification as well as the Link Detection Group to which it belongs. The Link Monitor is responsible for pinging that destination, processing responses and determining when the interface should be considered failed. It reports such failures to its Link Detection Group. As a best practice, configure link monitors for the active and standby SBC with different destinations to avoid a failure scenario where the active and standby SBC fail back and forth due to link detection failures caused by loss of communication with a single destination. The active and standby SBC should be connected to different physical hardware (that is, switches) to avoid a single point of failure.
Each Link Monitor that is configured can also be configured with unique values for the
Reattempt Timer, and
Maximum Retries. If configured, these values override the values configured for the Link Detection Group.
Each Link Monitor will set a timer while waiting to perform its next verification. The timeout for this timer is based on the configured
Verify Timer value. When a ping is in progress and the Link Monitor is awaiting the response from the destination, a timer is set based on the configured
Response Timer value. When the response times out and the Link Monitor retries, the
Reattempt Timer value is used while waiting for the response.
When the number of consecutive failures reaches the
Maximum Retries value, the Link Monitor considers the link verification as failed and reports this to its Link Detection Group.
While in the failed state, the Link Monitor will continue to attempt to ping the destination so that the failed condition can eventually clear. This is done at the rate specified by the
The Link Monitor also supports a NULL destination (0.0.0.0), which disables the link verification for that interface. The interface is still considered failed if there is a hardware failure.
Link Monitor verifies transport on a specific interface via Layer 3 ICMP/ARP/NUD to a specific destination or monitors MII state for the physical port, where MII is defined as “Media Independent Interface”.
To View Link Monitor
On SBC main screen, go to Configuration > System Provisioning > Category: Base Provisioning > Link Detection Group > Link Monitor. The Link Monitor window is displayed.
The Link Monitor can be checked for each Address Context or for each Link Detection Group or for all the Address Contexts and Link Detection Groups created. Use the drop-down box to select the desired Address Context and Link Detection Group.
To Edit Link Monitor
To edit any of the Link Monitors in the list, click the radio button next to the specific Link Monitor name.
The Edit Selected Link Monitor window is displayed below.
Make the required changes and click Save at the right hand bottom of the panel to save the changes made.
To Create Link Monitor
To create a new Link Monitor, click New Link Monitor tab on the Link Monitor List panel.
The Create New Link Monitor window is displayed.
The following fields are displayed:
Specifies the name of this Link Monitor Group.
Physical port associated with the IP interface to be monitored. In a redundancy configuration, pkt0_p is paired with pkt0_s and pkt1_p is paired with pkt1_s.
This parameter is only visible on SBC 7000 series systems.
|Specifies the name of the IP Interface Group to be monitored.|
Specifies the name of the IP or management interface to be monitored.
IP or MGMT interface can be configured, depending on the type that is configured for the Link Detection Group.
Specifies the destination IP Address for link verification.
The Destination IP Address must be within the same subnet as the source interface.
Specifies the time interval (in milliseconds) between the link verification attempts
Specifies the time to wait (in milliseconds) for a link verification attempt.
Specifies the time to wait (in milliseconds) for a link verification re-attempt.
Specifies the number of re-tries before the link verification is considered failed.
Specifies the administrative state for this link monitor.
Use this flag to enable/disable probing on the Standby port for the specified Link Monitor.
This flag is only visible on SBC 7000 series systems and used when Router cannot reply to the ARP probe with a required unicast destination MAC address.
To Copy Link Monitor
To copy any of the created Link Monitor and to make any minor changes, click the radio button next to the specific Link Monitor to highlight the row.
Click Copy Link Monitor tab on the Link Monitor List panel.
The Copy Selected Link Monitor window is displayed along with the field details which can be edited.
Make the required changes to the required fields and click Save to save the changes. The copied Link Monitor is displayed at the bottom of the original Link Monitor in the Link Monitor List panel.
To Delete Link Monitor
To delete any of the created Link Monitor, click the radio button next to the specific Link Monitor which you want to delete.
Click Delete at the end of the highlighted row. A delete confirmation message appears seeking your decision.
Click OK to remove the specific Link Monitor from the list.