eG Monitoring
 

Measures reported by CssRedunLinkTest

CSSs participate in a redundant configuration when a physical redundancy link has been defined between the CSSs. The CSSs use this link to maintain contact and activity status with one another. If the physical link goes down, the master CSS fails over to the backup CSS.

This test monitors the status of the redundancy links configured on a CSS.

 The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Redundant_link_status Indicates the current status of this redundant link. Boolean While the value 1 indicates that the link is up, the value 0 indicates that it is down.

There are two main conditions detected on this redundancy link that drive master and backup states on the CSSs:

The first condition is maintaining the heartbeat, which is an advertisement every second. The master CSS provides this heartbeat on the redundancy link, and the backup CSS keeps track of the heartbeat every three seconds (default). If the heartbeat times out (for example, heartbeats are not detected in this period), then link goes down and the backup takes over as master.

The second condition is that of a VRRP switch priority change. The CSS advertising the highest priority is negotiated to become master. This is the mechanism used by the uplink services, and some of the special commands (described below) for initiating a failover event.