Lesson 1 of 5

Wireless Architecture

Lab Objectives

  • Understand the difference between Autonomous Access Points (APs) and Lightweight APs, and when each is used in production.
  • Learn the role of a Wireless LAN Controller (WLC) and how CAPWAP tunnels operate between WLC and lightweight APs.
  • Practice basic switch configuration that supports wireless deployments: configuring a Dot1Q trunk and a redundant uplink using a port-channel (commands taken from the provided reference).

Lab Tasks (Try It Yourself First!)

Complete these tasks WITHOUT looking at the solution below. Use ? and show commands to figure it out.

Task 1: Configure a Dot1Q trunk for an AP uplink

On switch S1, configure the interface that will connect to an AP uplink as a Dot1Q trunk so multiple SSID VLANs (VLAN 10 Sales, VLAN 20 Engineering, VLAN 30 Management) can be carried to the AP or WLC uplink. Use the interface naming convention from the reference (E 0/2).

Task 2: Configure a redundant uplink using a manual Port-Channel

Between S1 and S2 create a manual (non-negotiated) port-channel using interfaces E 0/0 and E 0/1 on both switches. Configure the Port-Channel as a Dot1Q trunk to carry wireless VLANs and provide redundancy/bandwidth aggregation.

Task 3: Verify Spanning Tree and EtherChannel status

Verify Spanning Tree status for S1 and S2 and verify that the port-channel is operational. Determine the port roles on the root vs non-root bridge.

Think About It: Why do wireless networks commonly use Dot1Q trunks for AP uplinks rather than assigning access ports per SSID? How does this affect roaming and VLAN separation in a campus environment?


Lab Solution

Note: All configuration and verification commands used below are taken from the supplied reference material. Explanations cover WHY each command is required for a wireless deployment.

ASCII Topology (Base Lab Topology — exact IPs shown)

                [Internet]
               203.0.113.1
                    |
               R1 (Gateway)
              Gi0/0: 10.10.10.1
              Gi0/1: 10.10.20.1
              Gi0/2: 10.10.30.1
              /     |     \
           R2      R3      R4

Gi0/0: 10.10.10.2 | Gi0/0: 10.10.30.2 Gi0/1: 10.10.40.1 | / \ | S1 S2 S3 / \ | /
PC1 PC2 PC3 PC4 PC5

Device IP Scheme (for reference)

NetworkPurpose
10.10.10.0/24R1–R2 link
10.10.20.0/24R1–R3 link
10.10.30.0/24R1–R4 link
10.10.40.0/24R2–S1 link
192.168.1.0/24VLAN 10 — Sales
192.168.2.0/24VLAN 20 — Engineering
192.168.3.0/24VLAN 30 — Management
203.0.113.0/24Public / Internet simulation

Task 1 Solution: Configure a Dot1Q trunk for an AP uplink

What we are doing: Prepare the switch uplink port toward an AP (or a WLC uplink) to carry multiple wireless VLANs. Wireless SSIDs are commonly mapped to VLANs; Dot1Q trunks allow one physical connection to carry all SSID VLANs. This is essential for both autonomous APs configured with multiple VLANs (native configuration on the AP) and lightweight APs that tunnel client traffic to a WLC.

SW1# configure terminal
SW1(config)# interface range E 0/2 -3
SW1(config-if-range)# switchport trunk encapsulation dot1q
SW1(config-if-range)# switchport mode trunk

What just happened:

  • interface range E 0/2 -3 — selects the physical interface(s) on the switch that connect to AP(s) or uplinks. Using a range lets you configure multiple AP ports consistently.
  • switchport trunk encapsulation dot1q — sets the trunk protocol to 802.1Q (Dot1Q). This encodes VLAN tags so multiple VLANs can traverse the single physical link.
  • switchport mode trunk — places the interface into trunking mode so it will carry tagged frames for the VLANs. For wireless, native/default VLAN considerations matter (usually only management VLAN left untagged if used).

Verify:

SW1# show spanning-tree

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    32769
             Address     0011.2233.4455
             This bridge is the root
             Hello Time 2 sec  Max Age 20 sec  Forward Delay 15 sec

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
E0/2             Desg FWD 4         128.2    P2p
E0/3             Desg FWD 4         128.3    P2p


<div class="topology-diagram">
<img src="data:image/svg+xml;base64,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" alt="Network Topology Diagram" style="max-width:100%;height:auto;background:#fff;padding:16px;border:1px solid #e5e7eb;border-radius:8px;" />
</div>

cisco
SW1# configure terminal
SW1(config)# interface range E 0/0 -1
SW1(config-if-range)# channel-group 12 mode on
SW1(config-if-range)# no shut
SW1(config)# interface port-channel 12
SW1(config-if)# switchport trunk encapsulation dot1q
SW1(config-if)# switchport mode trunk

What just happened:

  • interface range E 0/0 -1 — selects the two physical interfaces that will be bundled.
  • channel-group 12 mode on — places the chosen interfaces into EtherChannel group 12 in manual mode (no negotiation like LACP/PAgP). This matches the reference’s manual port-channel setup.
  • no shut — ensures interfaces are administratively up.
  • interface port-channel 12 — configures the logical aggregated interface.
  • switchport trunk encapsulation dot1q and switchport mode trunk — configure the port-channel as a Dot1Q trunk so it carries multiple wireless VLANs.

Verify:

SW1# show etherchannel summary

Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
Number of channel-groups in use: 1
Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
12     Po12         -           Eth0/0(P) Eth0/1(P)


<div class="topology-diagram">
<img src="data:image/svg+xml;base64,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" alt="Network Topology Diagram" style="max-width:100%;height:auto;background:#fff;padding:16px;border:1px solid #e5e7eb;border-radius:8px;" />
</div>

cisco
SW1# show spanning-tree

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    32769
             Address     0011.2233.4455
             This bridge is the root
             Hello Time 2 sec  Max Age 20 sec  Forward Delay 15 sec

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Po12             Desg FWD 4         128.12   P2p
E0/2             Desg FWD 4         128.2    P2p
E0/3             Desg FWD 4         128.3    P2p


<div class="topology-diagram">
<img src="data:image/svg+xml;base64,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" alt="Network Topology Diagram" style="max-width:100%;height:auto;background:#fff;padding:16px;border:1px solid #e5e7eb;border-radius:8px;" />
</div>

cisco
SW1# show spanning-tree
  • If the port is not showing as a trunk or is not allowing VLANs, re-apply commands in correct order:
SW1# configure terminal
SW1(config)# interface range E 0/2 -3
SW1(config-if-range)# switchport trunk encapsulation dot1q
SW1(config-if-range)# switchport mode trunk
  • After applying, verify with show spanning-tree and check that the expected ports are in FWD and Desg roles.

Real-world note: On some platforms, if switchport trunk encapsulation is unsupported, the platform may default to 802.1Q. Always check the platform capability in production. In this lab, the explicit Dot1Q command matches the reference.

Verification Checklist

  • The AP uplink port(s) (E 0/2 -3 on S1) are configured as Dot1Q trunks.
  • The S1–S2 uplink is aggregated into Port-Channel 12 and Port-Channel 12 is a Dot1Q trunk.
  • show etherchannel summary shows both interfaces bundled in Po12.
  • show spanning-tree shows trunk and port-channel ports in forwarding state (Desg FWD for designated ports on the root or non-root bridge as appropriate).

Common Mistakes

SymptomCauseFix
Only one VLAN is reachable across the AP uplinkTrunk not configured; port is still an access portConfigure switchport trunk encapsulation dot1q followed by switchport mode trunk on the AP uplink interfaces
Port-channel shows interfaces as stand-aloneMismatched channel-group configuration on the peer or negotiation mode mismatchEnsure both sides use channel-group 12 mode on (manual) and configure the interface port-channel 12 trunk settings
AP loses connectivity after STP reconvergenceTrunk or port-channel placed in blocking state due to STP priorities/topologyCheck show spanning-tree and adjust STP root priorities or port costs if needed to ensure intended traffic paths

Challenge Task

  • Goal: Configure S1 and S2 so that the Port-Channel is active and preferred (forwarding) for VLAN 20 while a backup physical path exists for VLAN 10 on a single link. Do not follow step-by-step — use your understanding of trunking, port-channels, and spanning-tree to implement this design and verify operation.

Tip: Think of a lightweight AP as a "thin client" that offloads intelligence to the WLC; CAPWAP is the secure tunnel that carries control and data between APs and the WLC. Autonomous APs are like self-contained routers — they do the forwarding and client management locally. In production, large campuses use lightweight APs + WLCs for centralized policy, while small branch sites might use autonomous APs for simplicity.