Verification & Packet Tracer Assembly Guide: PTL-0006

Lab ID: PTL-0006
Lab Title: Configuring Layer 2 EtherChannel with LACP
Category: switching
Difficulty: Intermediate

1. Physical & Packet Tracer Assembly Manifest#

Device Hardware & Module Schedule#

Port-to-Port Cabling Matrix#

Addressing Table#

2. Pre-Configuration & Starter State#

In the starter state (starter):

• Dual physical links connect S1 and S2 on Fa0/1 and Fa0/2.
• Without EtherChannel, Spanning Tree Protocol (STP) blocks one link to prevent Layer 2 loops (one amber LED, one green LED). Total bandwidth is constrained to 100 Mbps.
• Student must configure 802.3ad LACP (channel-group 1 mode active on both switches), verify the formation of logical interface Port-channel 1, observe both physical ports transition to forwarding green LEDs, and verify aggregate 200 Mbps full-duplex throughput.

Complete reference configurations:

• configs/S1.txt
• configs/S2.txt

3. Positive Verification Tests#

Test POS-01: EtherChannel Summary Verification#

• Action: At S1#, issue show etherchannel summary.
• Expected Terminal Output:

  S1# show etherchannel summary
  Flags:  D - down        P - in port-channel
          I - stand-alone s - suspended
          H - Hot-standby (LACP only)
          R - Layer3      S - Layer2
          U - in use      f - failed to allocate aggregator
  ...
  Group  Port-channel  Protocol    Ports
  ------+-------------+-----------+-----------------------------------------------
  1      Po1(SU)         LACP      Fa0/1(P)    Fa0/2(P)    
  

• Criterion:
  • Port-channel flag shows (SU): S = Layer2, U = In Use.
  • Protocol shows LACP.
  • Both physical member ports show (P) = In Port-channel.

Test POS-02: Port-Channel Trunking Status#

• Action: At S1#, issue show interfaces trunk.
• Expected Terminal Output:

  S1# show interfaces trunk
  Port        Mode             Encapsulation  Status        Native vlan
  Po1         on               802.1q         trunking      1
  

• Criterion: Logical interface Po1 is operating as an 802.1Q trunk.

Test POS-03: End-to-End Host Communication Across the Bundle#

• Action: From PC-A (192.168.1.1), ping PC-B (192.168.1.2).
• Expected Terminal Output:

  C:\> ping 192.168.1.2
  Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
  Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
  Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
  Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
  

• Criterion: 100% packet success across the Port-Channel.

4. Negative Verification Tests#

Test NEG-01: Link Failover & Redundancy Test#

• Action: While running continuous ping from PC-A, shut down physical member link Fa0/1 on Switch S1 (interface Fa0/1 -> shutdown).
• Expected Behavior:
  • Terminal logs: %LINK-5-CHANGED: Interface FastEthernet0/1, changed state to administratively down
  • Re-issue show etherchannel summary: Port-channel Po1(SU) remains in use with Fa0/2(P) carrying all traffic.
  • Ping experiences at most 1 dropped packet during failover, then resumes successfully.

Test NEG-02: LACP Mode Incompatibility Test#

• Action: Change S1 to channel-group 1 mode passive and S2 to channel-group 1 mode passive.
• Expected Behavior:
  • When both ends are configured in passive mode, neither switch initiates LACP negotiation.
  • show etherchannel summary shows Po1(SD) (D = down), and member ports show (I) (stand-alone).

5. Diagnostic & Troubleshooting Reference#