HP Virtual Connect Version 3.61 Release Notes

Appendix: Feature details 15
Appendix: Feature details
Pause flood port protection
Ethernet switch interfaces use pause frame based flow control mechanisms to control data flow. When a
pause frame is received on a flow control enabled interface, the transmit operation is stopped for the pause
duration specified in the pause frame. All other frames destined for this interface are queued up. If another
pause frame is received before the previous pause timer expires, the pause timer is refreshed to the new
pause duration value. If a steady stream of pause frames is received for extended periods of time, the transmit
queue for that interface continues to grow until all queuing resources are exhausted. This condition severely
impacts the switch operation on other interfaces. In addition, all protocol operations on the switch are
impacted because of the inability to transmit protocol frames. Both port pause and priority-based pause
frames can cause the same resource exhaustion condition.
VC provides the ability to monitor server downlink ports for pause flood conditions and take protective action
by disabling the port. The default polling interval is 10 seconds and is not customer configurable. VC
provides system logs and SNMP traps for events related to pause flood detection.
This feature operates at the physical port level. When a pause flood condition is detected on a Flex-10
physical port, all Flex-10 logical ports associated with physical ports are disabled.
When the pause flood protection feature is enabled, this feature detects pause flood conditions on server
downlink ports and disables the port. The port remains disabled until an administrative action is taken. For
more information, see "Configuring pause flood protection settings (on page 20)."
The SNMP agent supports trap generation when a pause flood condition is detected or cleared.
Virtual Connect provides the ability to enable or disable port pause flood protection. The feature is enabled
by default and applies to all VC-Enet modules in the domain. Port pause floods are detected and server ports
can be disabled even prior to any enclosure being imported.
User interface
In the GUI, a check box is provided in the Advanced Settings tab of Ethernet Settings screen to enable and
disable pause flood protection.
The check box for pause flood protection under port protection is enabled by default. You can disable the
pause flood protection feature by selecting the check box, and then clicking Apply.
If you disable this feature, the GUI displays a warning: "If Pause Flood protection is disabled, any server
ports that are currently disabled due to pause flood detection are re-enabled."
When a pause flood condition occurs a small icon appears beside the "Enable Pause Flood Protection"
checkbox. You can recover any server ports that have been disabled by this feature by clicking Re-Enable
Ports.
The following screen shots describe feature configuration and status reporting using GUI.
Advanced Ethernet Settings