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EtherChannel — three cables, one logical link
Enterprise Intermediate 4 devices 5 checked tasks 100 points Plan lab
Spanning tree is blocking two of three uplinks. Bundle them with LACP so all three carry traffic, then read why a member refuses to join when the two ends disagree. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
Spanning tree is blocking two of three uplinks. Bundle them with LACP so all three carry traffic, then read why a member refuses to join when the two ends disagree.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 5 goals show as passed (100 points).
Network status
Devices: 2 PCs, 2 switchs, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. PC1 is a host with 10.40.1.10/24. PC2 is a host with 10.40.1.20/24. SW1, SW2 start with an empty configuration. Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
A Port-channel exists on both switches (15 pts) All three uplinks are bundled on SW1 (20 pts) All three uplinks are bundled on SW2 (20 pts) Spanning tree blocks nothing — the bundle is one link (25 pts) PC1 still reaches PC2 across the bundle (20 pts) The activity, in order
A Port-channel exists on both switches Why: EtherChannel joins links into one logical link, so spanning tree does not block the extras. Verify with: show etherchannel summary All three uplinks are bundled on SW1 Why: EtherChannel joins links into one logical link, so spanning tree does not block the extras. Verify with: show etherchannel summary All three uplinks are bundled on SW2 Why: EtherChannel joins links into one logical link, so spanning tree does not block the extras. Verify with: show etherchannel summary Spanning tree blocks nothing — the bundle is one link Why: Each goal is a state the lab can check on the running device. Verify with: show running-config PC1 still reaches PC2 across the bundle Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 10.40.1.20 Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Why this matters
Spanning tree is blocking two of three uplinks. Bundle them with LACP so all three carry traffic, then read why a member refuses to join when the two ends disagree.
What you will be able to do
A Port-channel exists on both switches
All three uplinks are bundled on SW1
All three uplinks are bundled on SW2
Spanning tree blocks nothing — the bundle is one link
The network
PC, Switch 8-port — 4 devices in all, already cabled.
Fa0 Fa0/8 Fa0 Fa0/8 Fa0/1 Fa0/1 Fa0/2 Fa0/2 Fa0/3 Fa0/3 PC1 10.40.1.10/24 PC2 10.40.1.20/24 SW1 SW2 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
PC1 PC 10.40.1.10 / 255.255.255.0 PC2 PC 10.40.1.20 / 255.255.255.0 SW1 Switch 8-port configure it SW2 Switch 8-port configure it
Cabling
PC1 Fa0 ↔ SW1 Fa0/8 PC2 Fa0 ↔ SW2 Fa0/8 SW1 Fa0/1 ↔ SW2 Fa0/1 SW1 Fa0/2 ↔ SW2 Fa0/2 SW1 Fa0/3 ↔ SW2 Fa0/3
What is configured at the start
Nothing is configured to start with beyond the addresses above: you build the configuration from a clean start.
Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 A Port-channel exists on both switches 15 On SW1: show etherchannel summary — the port-channel has 3 bundled members. and On SW2: show etherchannel summary — the port-channel has 3 bundled members. 2 All three uplinks are bundled on SW1 20 On SW1: show etherchannel summary — the port-channel has 3 bundled members. 3 All three uplinks are bundled on SW2 20 On SW2: show etherchannel summary — the port-channel has 3 bundled members. 4 Spanning tree blocks nothing — the bundle is one link 25 Checked automatically against the device’s live state (blocked). 5 PC1 still reaches PC2 across the bundle 20 On PC1: ping 10.40.1.20 must succeed.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
SW1 interface range f0/1 - 3
channel-group 1 mode active SW2 interface range f0/1 - 3
channel-group 1 mode passive Where this is examined
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
The lessons all guided labs plans
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