Cisco CATALYST 2960 - Availability and Redundancy Features; Automatic stack master re-election for replacing stack masters that become unavailable (failover support); Cross-stack EtherChannel for providing redundant links across the switch stack; UniDirectional Link Detection (UDLD) and aggressive UDLD for detecting and disabling unidirectional links on fiber-optic interfaces caused by incorrect fiber-optic wiring or port faults

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Catalyst 2960 Switch Command Reference
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Chapter 2 Catalyst 2960 Switch Cisco IOS Commands
channel-protocol
Related Commands Command Description
channel-group Assigns an Ethernet port to an EtherChannel group.
show etherchannel protocol Displays protocol information the EtherChannel.