Cisco Wireless Architectures And AP Modes
In order to provide secure data transfer, Cisco Wireless Architectures and Access Point (AP) modes are essential elements that dictate how APs are connected to and controlled inside a wired network infrastructure. The three primary architectural types of Cisco wireless deployments are Cloud-Based, Split-MAC (Lightweight/Controller-Based), and Autonomous.
Autonomous AP Architecture
The term “autonomous architecture” describes a stand-alone management system in which the AP is self-sufficient and manages every task on its own. The term “fat” AP is frequently used to describe it.
- Functionality: Everything is “under the Autonomous AP’s control.” It manages the development and administration of wireless networks, including the approval of association requests, radio frequency (RF) management, transmitter power management, and basic service set (BSS) management.
- Networking: By connecting Service Set Identifiers (SSIDs) to wired Virtual LANs (VLANs), the AP functions as a logical extension of the switched network. An AP must use a trunk link to connect to the network if it supports several WLANs that correspond to several VLANs.
- Management Challenge: The administrator must log in to each AP separately for both initial setup and any follow-up configuration adjustments (such as adding VLANs or modifying RF characteristics), which makes management difficult. As the network expands, this decentralized method frequently necessitates human channel and transmit power management to prevent interference and coverage gaps.
- Centralized Tools: In order to facilitate wireless network monitoring and configuration dashboards, Cisco provides centralized management software solutions, such as Cisco DNA Centre or Cisco Prime Infrastructure. Nevertheless, the duties themselves continue to place a significant burden on the access points. The local MAC architecture is another name for this.
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Cloud-Based AP Architecture (Cisco Meraki)
In order to solve network scalability issues with the Autonomous AP concept, Cisco unveiled Cisco Meraki, a cloud-based wireless architecture.
- Management Location: The provider’s server farms (the cloud) house the management software, which is not placed on the property.
- AP Role: Although the management responsibilities are now handled in the cloud, the APs function similarly to autonomous APs.
- Operations: The AP only handles real-time data transmission tasks. The Cisco Meraki dashboard, which automatically monitors RF parameters and transmits code updates and configuration changes, enables central management. A Cisco Meraki AP automatically configures itself after registering with the service.
- Features: Meraki APs are regarded as a unique instance; they are more intelligent than a lightweight AP that solely relies on the cloud for centralized control.
Split-MAC Architectures (Lightweight APs/WLC-Based)
By centralizing management, the Split-MAC architecture aims to increase client roaming flexibility and offer an Extended Service Set (ESS). A Wireless LAN Controller (WLC) is necessary for this architecture.
- Split-MAC Concept: The AP and the WLC perform “split” MAC layer functions.
◦ WLC (Control Plane): Manages non-delay-sensitive management tasks. Centralized configuration, RF management, security management, client authentication, Quality of Service (QoS), and association/reassociation (roaming) are some of these.
◦ Lightweight Access Point (LAP) (Data Plane): This mode is used by the AP. LAPs lack intelligence and depend on the WLC to handle management duties. They oversee the real-time functions (Layers 1 and 2), including basic MAC management, data encryption and decryption, and 802.11 frame transfer.
- Connectivity (CAPWAP): The Control and Provisioning of Wireless Access Points (CAPWAP) tunnelling protocol is used to facilitate communication between LAPs and WLCs.
◦ CAPWAP Control Tunnel: Transports encrypted control messages required to set up and oversee the LAP’s operation via UDP port 5246.
◦ CAPWAP Data Tunnel: This method transfers data to and from wireless clients over UDP port 5247. Datagram Transport Layer Security (DLTS) protects data packets, however they are not encrypted by default.
- Networking Benefit: LAPs and WLCs are logically separated when CAPWAP is used. While the CAPWAP tunnel carries the traffic to the central WLC, an LAP can be connected to an access mode switch port in one VLAN (e.g., VLAN 11) while providing SSIDs associated with different VLANs (e.g., VLAN 20 and 30).
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Cisco Access Point (AP) Modes
The main role of a Lightweight AP (LAP) is determined by its operating mode, which is normally set on the Wireless LAN Controller (WLC):
Local Mode (Default): Clients can connect wirelessly to the AP. A CAPWAP data tunnel is typically used to handle all client traffic before it is sent back to the WLC (centralized switching).
FlexConnect Mode: Originally known as H-REAP, FlexConnect Mode was created for remote offices.
- Traffic can be locally switched (leaving the AP’s local LAN port) or centrally switched (tunnelling back to the WLC) while the link to the WLC is up (Connected state).
- It can locally switch traffic for connected clients when the WLC connection is down (in the standalone state), guaranteeing local connectivity and lowering reliance on the WAN.
Monitor Mode: No SSIDs are transmitted or client connections are accepted by the AP’s radio. It serves as a specialized sensor to collect Radio Frequency (RF) statistics, monitor the wireless spectrum, and identify rogue devices.
Sniffer Mode: In Sniffer Mode, the AP functions as a specialized 802.11 packet capture device, sending the wireless traffic it has collected to a network analyzer program (such as Wireshark) for in-depth examination and troubleshooting.
Rogue Detector Mode: By comparing MAC addresses observed on the wired and wireless sides, the AP is tasked with identifying rogue access points linked to the wired network.
Bridge Mode/Mesh Mode: Used to generate self-forming, self-healing wireless mesh networks in hard-to-wire locations or to establish wireless point-to-point or point-to-multipoint links to bridge wired networks.
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