CCNA 200-301 v1.1 reference — Network Access

EtherChannel and LACP

Layer 2 and Layer 3 bundles, LACP negotiation modes, member-link compatibility rules, and interpreting EtherChannel flags.

Objective 2.4v1.1 exam target

Quick Reference Handbook

EtherChannel and negotiation

EtherChannel bundles physical links into one logical port-channel interface — the member limit is platform dependent (commonly 2–8); a bundle can even operate with a single member. STP and the routing table see a single link — no blocked redundant paths — while traffic load-balances across members using a hash of frame fields. LACP (802.3ad/802.1AX) is the standard negotiation protocol; PAgP is the Cisco-proprietary alternative; on forces a bundle with no negotiation.

LACP mode combinations

PAgP equivalents: desirable/desirable or desirable/auto form; auto/auto does not.
Side A	Side B	Result
active	active	Bundle forms
active	passive	Bundle forms (active initiates)
passive	passive	No bundle — neither side initiates
on	on	Forms with no negotiation — use with care
LACP	PAgP/on	No bundle — protocols don't mix

PAgP equivalents: desirable/desirable or desirable/auto form; auto/auto does not.

Member compatibility requirements

Same speed and duplex on all members.
Same port mode (access/trunk) and the same VLAN/allowed-VLAN set.
Same STP cost contribution rules apply to the bundle as one logical link.
Consistent EtherChannel config on both ends — mismatched members can shut the bundle down.

LACP configuration

Load balancing is per-flow, not per-packet: the hash (source/destination MAC, IP, or ports depending on platform) pins each conversation to one member. A single TCP session cannot exceed one member's bandwidth — the aggregate benefit is across many flows, not inside one.

Configure a Layer 2 LACP bundle

Bundle Gi1/0/1-2 into Po1 as a trunk — Privileged EXEC → Interface configuration

Cisco IOS / IOS XE

configure terminal
interface range gigabitethernet1/0/1 - 2
 channel-group 1 mode active
 exit
interface port-channel 1
 switchport mode trunk
 switchport trunk allowed vlan 10,20,30
 end

Verify

show etherchannel summary
show lacp neighbor
show interfaces port-channel 1

Members show (P) — bundled in the port-channel; (D)/(I) means down/stand-alone.
Po1 shows up/up with the trunk config inherited from the port-channel interface.

Layer 3 EtherChannel: no switchport + an IP on the port-channel interface instead.
Apply interface-level settings to the port-channel — members inherit them.

Changes device configuration.

$ show etherchannel summary (interpreted)

Group Port-channel Protocol PortsOne line per bundle.

1 Po1(SU) LACP Gi1/0/1(P) Gi1/0/2(P)SU = Layer 2, in use; (P) = bundled member.

Flags: D - down P - bundled in port-channelLearn the flag legend, not just the ports.

s - suspended S - Layer2 U - in useSuspended members signal a config mismatch.

Why the bundle stayed down

SW1: channel-group 1 mode passive
SW2: channel-group 1 mode passive

LACP needs an active side to send LACPDUs and propose the bundle.
Passive/passive means both wait politely forever — no negotiation starts.
Members never bundle; links stay individual (flag (I) stand-alone).

Set at least one side to active (or use on/on where negotiation isn't wanted).

Verification

Common mistakes

Expecting one flow to use aggregate bandwidth — hashing pins flows to single members.
Mixing LACP and PAgP or 'on' between the same pair — they do not interoperate.
Configuring trunk/allowed-VLAN on members instead of the port-channel.
Overlooking member mismatches (speed, duplex, VLAN) — LACP suspends non-conforming links.
Using passive/passive and wondering why nothing forms.

Member shows suspended

Observation: show etherchannel summary lists Gi1/0/2 as (s) suspended while Gi1/0/1 is bundled.

Hypotheses

Interface-level mismatch (speed/duplex/VLAN) on member 2
Far-end port not in the same channel-group
Different bundle modes on that member

Check	Indicates
`show run` on both member interfaces both sides	Identical speed/duplex/switchport config required.
`show lacp neighbor`	Reveals which partner ports LACP actually sees.
CDP/LLDP neighbor on Gi1/0/2	Confirms the cable lands where you think it does.

Correction: Make member configs identical and re-add to the channel-group.

Both members show (P) and Po1 reports full bandwidth.

On this page

EtherChannel and negotiation
LACP configuration
Verification

Related resources

Practise this topic Source topic 23: EtherChannel (Link Aggregation)Practise topic 23 deck

Sources

Cisco CCNA 200-301 v1.1 Exam Topics (official PDF) — reviewed 2026-11-02
IEEE 802.1 Working Group (802.1AX link aggregation) — reviewed 2026-11-02
Cisco — LAN Switching Command Reference — reviewed 2026-11-02

Targets CCNA 200-301 v1.1 objectives. Supplemental blocks are labeled beyond exam scope.