In which configuration mode is show etherchannel protocol used?

The show etherchannel protocol command is entered in Privileged EXEC mode on Cisco IOS devices.

EtherChannelPrivileged EXEC

show etherchannel protocol

Displays the protocol (LACP or PAgP) used by each EtherChannel bundle, useful for verifying that all member ports are using the same negotiation protocol.

Definition: show etherchannel protocol is a Cisco IOS privileged exec command. Displays the protocol (LACP or PAgP) used by each EtherChannel bundle, useful for verifying that all member ports are using the same negotiation protocol.

Overview

The 'show etherchannel protocol' command is a vital diagnostic tool in Cisco IOS that reveals which link aggregation protocol—LACP (IEEE 802.3ad) or PAgP (Cisco proprietary)—is active on each EtherChannel bundle. EtherChannel technology allows multiple physical Ethernet links to be bundled into a single logical link, providing increased bandwidth and redundancy. The protocol used determines how ports negotiate and maintain the bundle: LACP is an open standard, enabling interoperability with non-Cisco devices, while PAgP is Cisco proprietary and offers additional features like automatic creation and adjustment.

This command is essential when verifying that all member ports in a channel-group are consistently configured with the same protocol; mismatched protocols can cause the bundle to fail to form or operate incorrectly. Network engineers reach for this command during initial configuration validation, after making changes to channel-group parameters, or when troubleshooting EtherChannel issues such as ports not joining the bundle, flapping links, or unexpected traffic behavior. Unlike 'show etherchannel summary' which provides a high-level status of bundles, or 'show etherchannel port' which details individual port states, this command focuses specifically on the protocol in use, making it the go-to for protocol mismatch detection.

It fits into the broader workflow of configuring and troubleshooting link aggregation: after configuring channel-group mode (active/passive for LACP, desirable/auto for PAgP), you verify with this command; if issues arise, you correlate its output with 'show etherchannel detail' and 'show interfaces' to isolate problems. Important IOS behaviors include that the output is buffered (use 'terminal length 0' to avoid paging), the command requires privileged EXEC mode (enable), and it does not affect the running configuration—it is a read-only diagnostic. Understanding the protocol in use is critical because LACP and PAgP are not interoperable; a bundle cannot form if one side uses LACP and the other PAgP.

Additionally, some IOS versions may display the protocol as 'LACP' or 'PAgP' while others show '802.3ad' or 'Cisco'; familiarity with these variations prevents confusion. This command also helps in multi-vendor environments where LACP is mandatory for interoperability, ensuring that all devices adhere to the standard. In summary, 'show etherchannel protocol' is a simple yet powerful command that provides immediate insight into the link aggregation protocol configuration, enabling engineers to quickly validate and troubleshoot EtherChannel deployments.

Syntax·Privileged EXEC

show etherchannel protocol

When to Use This Command

Verify that all ports in a bundle are using LACP (active/passive) or PAgP (desirable/auto) after configuration.
Troubleshoot why an EtherChannel is not forming due to protocol mismatch between switches.
Confirm that a port channel is using the intended protocol before making changes to the bundle.
Audit existing EtherChannel configurations across multiple switches for consistency.

Command Examples

Basic show etherchannel protocol

show etherchannel protocol

EtherChannel Protocol: LACP

Channel-group 1:
	Ports: Gi0/0, Gi0/1
	Protocol: LACP

Channel-group 2:
	Ports: Gi0/2, Gi0/3
	Protocol: PAgP

Line 1: The global EtherChannel protocol is LACP (set by 'lacp system-priority' or default). Channel-group 1: Shows that ports Gi0/0 and Gi0/1 are using LACP. Channel-group 2: Shows that ports Gi0/2 and Gi0/3 are using PAgP.

Show etherchannel protocol with no bundles

show etherchannel protocol

EtherChannel Protocol: LACP

No EtherChannel bundles configured.

Indicates that the global protocol is LACP but no port channels have been created yet.

Understanding the Output

The first line shows the global EtherChannel protocol (LACP or PAgP) configured on the switch. This is set by the 'lacp system-priority' command for LACP or 'pagp system-priority' for PAgP. Then, for each channel-group, it lists the member ports and the protocol they are using.

All ports in a channel-group must use the same protocol; otherwise, the bundle will not form. If you see a mix of protocols in the same group, there is a configuration error. The output also helps verify that the correct protocol is being used (e.g., LACP for cross-vendor links).

Configuration Scenarios

Verify LACP Protocol on an EtherChannel Bundle

A network engineer has configured an EtherChannel between two Cisco switches using LACP. After configuration, they need to confirm that all member ports are using LACP and not PAgP, ensuring interoperability with a non-Cisco device downstream.

Topology

SW1(Gi0/1-2)---EtherChannel---(Gi0/1-2)SW2

Steps

1.Step 1: Enter privileged EXEC mode on SW1: SW1> enable
2.Step 2: Run the command: SW1# show etherchannel protocol
3.Step 3: Examine the output to confirm that the channel-group number (e.g., 1) shows 'LACP' as the protocol.

Configuration

! On SW1, configure LACP active mode on ports Gi0/1 and Gi0/2
interface GigabitEthernet0/1
 channel-group 1 mode active
!
interface GigabitEthernet0/2
 channel-group 1 mode active

Verify: SW1# show etherchannel protocol Channel-group 1: Protocol: LACP If the output shows 'PAgP' instead, the ports are misconfigured.

Watch out: A common mistake is configuring one port with 'mode active' and another with 'mode passive' (both LACP) but forgetting that the remote side must also be configured with LACP (active or passive). The 'show etherchannel protocol' command only shows the local protocol; use 'show etherchannel summary' to see if the bundle is up.

Troubleshoot Protocol Mismatch in an EtherChannel

An EtherChannel bundle between two Cisco switches is not forming. The engineer suspects a protocol mismatch because one switch was configured with PAgP and the other with LACP. This scenario demonstrates using the command to identify the mismatch.

Topology

SW1(Gi0/1-2)---EtherChannel---(Gi0/1-2)SW2

Steps

1.Step 1: On SW1, enter privileged EXEC mode: SW1> enable
2.Step 2: Run: SW1# show etherchannel protocol
3.Step 3: Note the protocol displayed (e.g., PAgP).
4.Step 4: On SW2, run the same command: SW2# show etherchannel protocol
5.Step 5: Compare the protocols. If SW1 shows PAgP and SW2 shows LACP, there is a mismatch.

Configuration

! On SW1 (incorrectly configured with PAgP)
interface GigabitEthernet0/1
 channel-group 1 mode desirable
!
interface GigabitEthernet0/2
 channel-group 1 mode desirable
!
! On SW2 (correctly configured with LACP)
interface GigabitEthernet0/1
 channel-group 1 mode active
!
interface GigabitEthernet0/2
 channel-group 1 mode active

Verify: SW1# show etherchannel protocol Channel-group 1: Protocol: PAgP SW2# show etherchannel protocol Channel-group 1: Protocol: LACP The mismatch prevents the bundle from forming. Correct by changing one side to match the other.

Watch out: Engineers sometimes overlook that 'channel-group 1 mode desirable' uses PAgP, while 'channel-group 1 mode active' uses LACP. Always verify the protocol on both ends. Also, note that 'show etherchannel protocol' does not show the bundle status; use 'show etherchannel summary' to see if the bundle is up.

Troubleshooting with This Command

When troubleshooting EtherChannel issues, 'show etherchannel protocol' is often the first command to run after verifying physical connectivity. Healthy output displays a consistent protocol across all channel-groups, typically 'LACP' or 'PAgP'. For example:

Channel-group 1: Protocol: LACP

If the output shows no protocol for a channel-group (e.g., 'Protocol: N/A'), it indicates that the bundle has no member ports configured or the ports are in a down state. This is a problem indicator—check interface status and channel-group configuration. Another issue is when different channel-groups show different protocols; while this is allowed, it may indicate misconfiguration if the engineer intended a uniform protocol. The key field to focus on is the 'Protocol' line for each channel-group. Common symptoms that this command helps diagnose include: (1) EtherChannel not forming—if one side shows LACP and the other PAgP, the bundle will not come up; (2) ports not joining the bundle—if a port is configured with a different protocol than the channel-group, it will be placed in a suspended or standalone state; (3) intermittent flapping—if the protocol is misconfigured, ports may constantly renegotiate. A step-by-step diagnostic flow: Step 1: Run 'show etherchannel protocol' on both ends of the link. Step 2: Compare the protocols. If they differ, reconfigure one side to match. Step 3: If protocols match but the bundle is still down, run 'show etherchannel summary' to see the bundle state (SU for in use, SD for suspended, etc.). Step 4: Use 'show etherchannel detail' to see individual port states and reasons for suspension. Step 5: Check 'show interfaces' for errors or speed/duplex mismatches. Correlate this command's output with 'show etherchannel load-balance' to ensure consistent hashing, and with 'debug etherchannel' (use with caution) for real-time negotiation issues. Remember that LACP requires the system priority and port priority to be consistent; while 'show etherchannel protocol' does not show these, they can be verified with 'show lacp neighbor'. In summary, this command is a quick litmus test for protocol consistency, and when combined with other show commands, it forms the backbone of EtherChannel troubleshooting.

CCNA Exam Tips

CCNA exam may ask which protocol is used when both LACP and PAgP are configured on the same switch; the global protocol takes precedence.

Remember that LACP is IEEE standard and works with any vendor; PAgP is Cisco proprietary.

The 'show etherchannel protocol' command does not show the port channel number; use 'show etherchannel summary' for that.

If no bundles exist, the output still shows the global protocol.

Common Mistakes

Assuming all EtherChannels use the same protocol; they can be mixed per channel-group.

Confusing the global protocol with per-channel protocol; the global setting only affects new bundles.

Forgetting that LACP and PAgP cannot be mixed within the same channel-group.

show etherchannel protocol vs show etherchannel summary

Both show etherchannel protocol and show etherchannel summary are used to verify EtherChannel configuration, but they emphasize different aspects. The first focuses on the negotiation protocol per bundle, while the latter provides a comprehensive status overview, often leading to confusion when troubleshooting channel bundling issues.

Aspect	show etherchannel protocol	show etherchannel summary
Scope	Per-bundle protocol negotiation	All EtherChannel interfaces summary
Output detail	Protocol (LACP/PAgP) for each bundle	Status, ports, flags, protocol for each bundle
Port membership	Not displayed	Displayed via flags (e.g., P/FP)
Primary use	Verify protocol consistency across members	Verify channel bundling and overall state
Information density	Minimal, protocol-focused	Comprehensive, includes packet counters etc.

Use show etherchannel protocol when you need to verify that all member ports in an EtherChannel are using the same negotiation protocol (LACP or PAgP).

Use show etherchannel summary when you want a quick overview of all configured EtherChannels, including their status, port membership, and protocol state.

Platform Notes

In IOS-XE (e.g., Catalyst 3650/3850/9300), the 'show etherchannel protocol' command syntax and output are identical to classic IOS. However, on some IOS-XE platforms, the output may also include the 'Protocol' line for each channel-group, but the command is available. On NX-OS (e.g., Nexus 9000), the equivalent command is 'show port-channel database' or 'show port-channel summary' which includes protocol information.

Specifically, 'show port-channel database' displays the protocol (LACP or none) for each port-channel. For example: 'port-channel1: admin: LACP'. There is no direct 'show etherchannel protocol' on NX-OS.

On ASA firewalls, EtherChannel is supported but the command is 'show etherchannel' (without 'protocol') and the output includes protocol details. For ASA, use 'show etherchannel summary' to see protocol. In IOS-XR (e.g., ASR 9000), the command is not available; instead, use 'show lacp bundle' or 'show ethernet bundle' to view LACP status.

Regarding IOS version differences: in older IOS 12.x, the output might show 'PAgP' or 'LACP' explicitly; in 15.x and 16.x, the format remains consistent. However, some early 12.x versions may not support this command; use 'show etherchannel summary' as a fallback. Always check the specific platform documentation, as the command may be hidden or not supported on certain hardware (e.g., some 2960 models).

In summary, while the command is standard on IOS and IOS-XE, NX-OS and IOS-XR require different commands, and ASA uses a variant.

Related Commands

show etherchannel port

Displays detailed port-level information for all ports that are part of an EtherChannel bundle, including port state, aggregation protocol, and partner details.

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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