The polling timers provide an alternate way to detect ring breaks. In a ring that uses only Extreme Networks switches, the master switch learns about a ring break by receiving a link-down PDU. When the ring uses only Extreme networks switches, the polling timers are not needed and can remain configured for the default values.
In a ring that contains switches made by other companies, the polling timers provide an alternate way to detect ring breaks. The master periodically sends hello PDUs at intervals determined by the hello PDU timer and waits for a reply. If a hello PDU reply is not received before the failtime timer expires, the switch detects a failure and responds by either sending an alert or opening the secondary port. The response action is defined by a configuration command.
NoteThese commands apply only to the master node. If you configure the polling timers for a transit node, they are ignored. If you later reconfigure that transit node as the master node, the polling timer values are used as the current values.
Use the hellotime keyword and its associated parameters to specify the amount of time the master node waits between transmissions of health check messages on the control VLAN. The combined value for seconds and milliseconds must be greater than 0. The default value is 1 second.
Use the failtime keyword and its associated parameters to specify the amount of time the master node waits before the failtimer expires. The combined value for seconds and milliseconds must be greater than the configured value for hellotime. The default value is 3 seconds.
NoteIncreasing the failtime value increases the time it takes to detect a ring break using the polling timers, but it can also reduce the possibility of incorrectly declaring a failure when the network is congested.
Use the send-alert parameter to send an alert when the failtimer expires. Instead of going into a failed state, the master node remains in a Complete or Init state, maintains the secondary port blocking, and writes a critical error message to syslog warning the user that there is a fault in the ring. An SNMP trap is also sent.
Use the open-secondary-port parameter to open the secondary port when the failtimer expires.