Lightweight vs. Autonomous Access Points (APs)
Comprehensive Comparison, Architecture, and Practical Scenarios
Definition and Overview
What is an Autonomous AP?
An Autonomous Access Point (AP) (also called standalone AP) is a fully self-contained wireless device. It operates independently, is configured directly (via CLI or web GUI), and manages all its wireless and security settings locally. Each AP is managed, updated, and monitored individually.
Example: A small branch office has a single AP in the lobby, configured via its web interface, serving Wi-Fi to guests and staff without needing any central controller.
What is a Lightweight AP?
A Lightweight Access Point is designed to operate as part of a centrally managed wireless network. Most of its configuration and control (SSID, security, firmware, user access, etc.) are provided by a Wireless LAN Controller (WLC). The AP itself runs only the radio and minimal logic—the WLC does the rest.
Example: A university with hundreds of APs, all managed from a Cisco WLC in the data center. New SSIDs, security policies, and firmware are pushed automatically to every lightweight AP.
Architecture Differences
| Aspect | Autonomous AP | Lightweight AP |
|---|---|---|
| Operation | Standalone | Controller-based |
| Control Plane | Local on each AP | Centralized on WLC |
| Data Plane | Local | Local or Centralized (WLC) |
Management and Configuration
-
Autonomous APs: Individually configured using CLI, web GUI, or SNMP.
Example: Set up SSID and WPA2 security using the AP’s web interface. -
Lightweight APs: Managed collectively from the WLC.
Example: Create a new SSID in the WLC GUI; it is automatically deployed to all lightweight APs.
Firmware and Software Upgrades
- Autonomous: Each AP must be upgraded individually—a slow process in large deployments.
- Lightweight: Firmware is centrally distributed from the WLC to all joined APs, ensuring consistency and efficiency.
Deployment Scenarios
| Scenario | Recommended AP Type |
|---|---|
| Small office, remote branch (1–2 APs) | Autonomous AP |
| Large campus, high-density (50+ APs) | Lightweight AP + WLC |
| Temporary, isolated Wi-Fi | Autonomous AP |
| Centralized security & seamless roaming | Lightweight AP + WLC |
Feature Differences
| Feature | Autonomous AP | Lightweight AP (with WLC) |
|---|---|---|
| Security | WPA2, MAC filtering, limited 802.1X | Advanced 802.1X, guest portals, identity-based policies |
| Roaming | Basic; may drop sessions | Seamless, fast, secure (controller handles handoff) |
| Scalability | Limited (manual, 1–3 APs) | High (central management, 1000+ APs) |
| Flexibility | Good for isolated, static setups | Excellent for dynamic, evolving networks |
Communication Protocols
- Autonomous APs: Operate independently, do not use CAPWAP/LWAPP protocols.
- Lightweight APs: Communicate with WLC using CAPWAP (Control and Provisioning of Wireless Access Points, UDP ports 5246/5247) or older LWAPP.
Cost and Complexity
- Autonomous APs: Lower initial cost (no controller). Operational overhead rises as network grows.
- Lightweight APs: Require investment in WLC, but centralized management dramatically reduces long-term effort in large networks.
Troubleshooting Approaches
- Autonomous APs: Troubleshoot on each AP (CLI/web/console). Every AP might need separate attention.
- Lightweight APs: Troubleshoot from the WLC dashboard (central logs, monitoring, alerting). Reset/update APs remotely.
Migration and Hybrid Environments
- Migration: Some Cisco APs can convert between autonomous and lightweight images ("image swap"). Growing organizations often migrate to lightweight for manageability.
- Hybrid: In some deployments, both AP types may exist together (e.g., legacy APs remain standalone while new ones are managed by WLC).
Quick Comparison Table
| Aspect | Autonomous AP | Lightweight AP |
|---|---|---|
| Management | Local (each AP) | Central (WLC) |
| Config changes | Manual per AP | Pushed globally |
| Security | Limited 802.1X | Advanced/Identity-based |
| Roaming | May drop session | Seamless |
| Firmware update | Manual per AP | Automatic via WLC |
| Protocol | None (CAPWAP not used) | CAPWAP/LWAPP |
Configuration Example: Autonomous AP (Standalone)
Scenario: Configure a Cisco Autonomous AP for SSID "CompanyWiFi" with WPA2.
!
hostname AP-Standalone
!
interface Dot11Radio0
ssid CompanyWiFi
authentication open
authentication key-management wpa version 2
wpa-psk ascii 0 MySecurePassw0rd
!
interface Dot11Radio0
no shutdown
!
interface FastEthernet0
ip address dhcp
no shutdown
!
end
!
write memory
- Access the AP via console or SSH (enable mode).
- Configure radio, WPA2-PSK, wired interface, and save.
- For web GUI management, use the AP's IP address in your browser.
Configuration Example: Lightweight AP (WLC-managed)
Scenario: Deploy a new Lightweight AP to join Cisco WLC, create SSID "CompanyWiFi" with WPA2.
- Plug in AP (PoE) and connect to correct VLAN.
- Ensure DHCP Option 43, DNS, or L2 broadcast points AP to WLC.
- On WLC GUI:
- Create new WLAN: WLANs > Create New > Profile Name: CompanyWiFi
- SSID: CompanyWiFi
- Security: WPA2, set pre-shared key
- Assign WLAN to a VLAN/interface
- Monitor APs: Wireless > Access Points
- Assign name/location to AP for clarity
WLC CLI commands for monitoring:
show ap summary
show wlan summary
show client summary
Step-by-Step: Migrating Autonomous AP to Lightweight Mode
- Download lightweight image to a TFTP server (e.g.,
ap3g2-k9w8-tar.153-3.JF.tar). - Console/SSH to AP
- Transfer and install image:
archive download-sw /overwrite /force tftp://192.168.1.5/ap3g2-k9w8-tar.153-3.JF.tar - AP reboots in lightweight mode and joins WLC.
- Verify on WLC dashboard. Configuration now pushed from WLC.
CAPWAP Protocol: Key Facts
- Stands for Control and Provisioning of Wireless Access Points.
- Tunnels control and optionally data between APs and WLC (UDP 5246/5247).
- Ensures secure management (supports DTLS encryption).
- Enables fast deployment, monitoring, and troubleshooting.
Key Points & Exam Tips
- Autonomous AP: Standalone, local config, best for small/simple deployments, no controller.
- Lightweight AP: Centrally managed via WLC, CAPWAP tunnel, best for scalability, security, and roaming.
- Firmware, security, and SSID updates are easier with lightweight APs.
- Know the protocol: CAPWAP (lightweight) vs. none (autonomous).
- Troubleshooting: Focus on the device (autonomous) vs. the controller (lightweight).
- Migration is possible if the AP model supports image conversion.