channel-protocol [lacp|pagp]
Specifies the EtherChannel protocol (LACP or PAgP) to be used on an interface for link aggregation.
channel-protocol [lacp|pagp]When to Use This Command
- Configuring LACP on a trunk port connecting to a switch that supports only LACP
- Setting PAgP on a port channel between two Cisco switches that use Cisco proprietary PAgP
- Changing the protocol from PAgP to LACP to interoperate with a non-Cisco switch
- Ensuring both sides of an EtherChannel use the same protocol to avoid negotiation failures
Command Examples
Enable LACP on an interface
interface GigabitEthernet0/1
channel-protocol lacpSwitch(config-if)# channel-protocol lacp Switch(config-if)#
The command sets the EtherChannel protocol to LACP on interface GigabitEthernet0/1. No output is displayed if successful.
Enable PAgP on an interface
interface GigabitEthernet0/2
channel-protocol pagpSwitch(config-if)# channel-protocol pagp Switch(config-if)#
Sets the EtherChannel protocol to PAgP. No output indicates success.
Understanding the Output
The command does not produce any output on success; it simply configures the protocol. To verify, use 'show etherchannel summary' or 'show running-config interface'. In 'show etherchannel summary', the protocol column shows 'LACP' or 'PAgP' for each port-channel. If the protocol mismatches between ends, the port will not bundle. Ensure both sides use the same protocol and compatible modes (active/passive for LACP, desirable/auto for PAgP).
CCNA Exam Tips
CCNA exam tip: LACP is IEEE standard (active/passive modes); PAgP is Cisco proprietary (desirable/auto modes).
CCNA exam tip: You must set the same protocol on all interfaces in the bundle.
CCNA exam tip: The 'channel-protocol' command is optional if you use 'channel-group' with mode; the protocol is inferred from the mode keyword.
CCNA exam tip: Know that 'channel-protocol' is used before 'channel-group' to explicitly set the protocol.
Common Mistakes
Mistake 1: Setting different protocols on interfaces in the same port-channel, causing the bundle to fail.
Mistake 2: Forgetting to set the protocol on both sides; one side may default to PAgP while the other uses LACP.
Mistake 3: Using 'channel-protocol' after 'channel-group' — the command must be issued before 'channel-group' to take effect.
Related Commands
channel-group [id] mode [mode]
Assigns an interface to an EtherChannel bundle with a specified channel-group number and mode (active, passive, or desirable) to aggregate multiple physical links into a single logical link for redundancy and increased bandwidth.
show etherchannel summary
Displays the status and configuration of all EtherChannel interfaces on the switch, used to verify channel bundling, port membership, and protocol state.
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