BLADE OS™ Application Guide HP GbE2c Ethernet Blade Switch for c-Class BladeSystem Version 5.1 Advanced Functionality Software

Table Of Contents
BLADE OS 5.1 Application Guide
232 Chapter 14: High Availability BMD00113, September 2009
L2 Failover with Other Features
L2 Failover works together with Link Aggregation Control Protocol (LACP) and with Spanning
Tree Protocol (STP), as described below.
LACP
Link Aggregation Control Protocol allows the switch to form dynamic trunks. You can use the
admin key to add up to two LACP trunks to a failover trigger using automatic monitoring. When
you add an admin key to a trigger (/cfg/l2/failovr/trigger <x>/amon/addkey), any
LACP trunk with that admin key becomes a member of the trigger.
Spanning Tree Protocol
If Spanning Tree Protocol (STP) is enabled on the ports in a failover trigger, the switch monitors the
port STP state rather than the link state. A port failure results when STP is not in a Forwarding state
(that is, Listening, Learning, Blocking, or No Link). The switch automatically disables the
appropriate downlink ports, based on the VLAN monitor.
When the switch determines that ports in the trigger are in STP Forwarding state, then it
automatically enables the appropriate downlink ports, based on the VLAN monitor. The switch fails
back to normal operation.