Basic Concepts of WLAN Service Sets

concept	full name	describe
BSS	Basic Service Set BSS	Basic Service Unit for Wireless Networks Usually consists of an AP and several wireless terminals
ESS	Extended Service Set ESS	Consists of multiple BSSs using the same SSID Solve the problem of limited coverage of BSS
SSID	Service Set Identifier SSID	Used to distinguish different wireless networks.
ESSID	Extended Service Set Identifier ESSID	Identification of a wireless network or group of wireless networks The SSID in the group is the same
BSSID	Basic Service Set Identifier BSSID	Used on the link layer to distinguish different VAPs on the same AP It can also be used to distinguish BSS in the same ESS
VAP	Virtual Access Point VAP	Business function entity virtualized on the AP device Users can create different VAPs on one AP to provide wireless access services for different user groups.

The basic concept of AP

What is a wireless AP

Wireless AP (Access Point) is also called wireless access point, its function is to convert between wireless network and wired network; it is a communication bridge between wireless network and wired network; among them, AP is mainly divided into fat AP and thin AP according to the function

Classification of APs

What is a fat AP

Fat AP is a wireless AP that integrates antenna, encryption, authentication, gateway, roaming, security and other functions

The functions are all concentrated on the AP, with an independent control plane, which can work and maintain independently

That is: the fat AP has a simple routing and switching function

What is thin AP

Thin AP is a wireless AP that is only responsible for some functions such as wireless access and encryption. Other functions such as radio frequency management, user access, AP control, and roaming control are all migrated to the wireless controller (AC) to complete.

Thin AP does not have an independent control plane, and the control plane is migrated to AC; one AC can manage and control multiple APs

AP Mode Switching

Ruijie AP switching mode

ap-mode fit switch to thin AP

ap-mode fat switch to fat AP

ap-mode macc switch to cloud management mode

Huawei AP switching mode

ap-mode-switch fat switch to fat AP

Fat (FAT) AP Introduction

Working Mode of Fat AP

Log in to the AP, the default AP is a thin AP, you need to change the AP to a fat AP (ap-mode fat)

Then it will prompt the fat AP to use the access mode or the wireless routing mode

AP access mode

That is to say, the fat AP has the function of wireless AP + switch; it transparently transmits the data of wireless users in the network

The gateway of the wireless user is on the upper-layer device of the fat AP, and the address of the wireless user is generally distributed by the upper-layer device through DHCP

The AP interface obtains the address

Generally speaking, the AP has only one interface, which is used to connect devices uplink. In this mode, the uplink interface is a Layer 2 port.

You need to configure the corresponding Vlanif interface to obtain the address, only static and DHCP are supported

Precautions

If the upper-layer device of the AP is not configured with DHCP; you can enable DHCP on the AP, but the IP address corresponding to the Vlan of its uplink interface must belong to the same network segment as the upper-layer device

If the AP is not configured with DHCP, the address corresponding to the Vlan on the uplink interface of the AP can be any address; because this address does not participate in data forwarding, it is only used as the management address of the AP; however, it is recommended to be consistent with the uplink interface, so that when the AP configuration needs to be modified Yes, you can log in to the AP through wireless users

AP wireless routing mode

That is, the fat AP has the function of wireless AP + router

In this mode, the wireless user's gateway and DHCP are on the AP interface

Then configure NAT on the AP to convert the address of the wireless user to the address of the wired interface so that it can access the Internet

The AP interface obtains the address

Generally speaking, the AP has only one interface, which is used to connect devices uplink, and this interface is a layer-3 interface;

In this mode, the interface obtains an IP address in three ways: static, PPPoE, and DHCP

Precautions

If the upper-layer interface of the AP needs to obtain an address through PPPoE dial-up, the AP must be in routing mode at this time, and the upper-layer port must be configured as a dial-up port.

If you access the AP through a cable, you need to unplug the uplink port. If it is a dynamically obtained IP address, the dynamically obtained address will disappear at this time; at this time, the cable cannot access the AP; so when using a wired connection to the AP , the uplink port of the AP needs to be a static IP address

Difference between access mode and route mode

Access mode configuration is simple, less prone to errors; AP consumes less performance

Routing mode configuration is relatively complicated and error-prone; AP consumes a lot of performance

Networking Mode of Fat APs

Fat APs are generally used in small networks such as homes and enterprises

In the home network: the use of fat AP can not only meet the requirements of wireless coverage, but also can be used as a router at the same time to realize the routing and forwarding of the wired network

Thin (FIT) AP Introduction

Working Mode of Thin AP

How APs Interact with ACs

AP and AC exchange information by establishing a CAPWAP tunnel; AC controls all APs to deliver configurations, versions, etc. through the CAPWAP protocol

Because the CAPWAP protocol is not universal, it is not compatible between different manufacturers; that is, Ruijie's AC cannot manage Huawei's AP

The AP interface obtains the address

Generally speaking, the AP has only one interface, which is used to connect devices uplink.

Thin APs only support static and DHCP to obtain IP addresses; DHCP is enabled on the default interface, and you can go online directly through AC zero configuration

Networking Mode of Thin APs

Thin APs are generally used in medium and large networks such as campuses and hotels

Classify according to the network architecture between AP and AC

Between the AC and the AP can be a layer 2 network, a layer 3 network, a tunnel, a traversal NAT node, etc.

Layer 2 networking—AC and AP belong to the same Layer 2 network;

Layer 2 networking is generally a temporary networking, which can be configured quickly, but it is not suitable for larger networks

Layer 3 networking—there is a layer 3 network between AC and AP;

Layer 3 networking is generally more complicated and is applied to larger networks

Classified according to the location of the AC on the network

Direct connection networking

AC plays the role of AC and aggregation switch at the same time, and has relatively high throughput and data processing capacity for AC.

The data service and management service of the AP are centrally processed and forwarded by the AC.

Side-mounted networking

Generally, the AC is bypassed on the switch (generally bypassed on the core/aggregation switch)

This method is easy to expand the network and does not require high AC throughput.

The recommended AP networking method is: side-mounted AP + three-layer networking

The difference between fat AP and thin AP

Fat AP: full-featured, independent control, suitable for small-scale networks, only capable of Layer 2 roaming

Thin AP: Fewer functions, requires AC to control and issue configuration (AC manages multiple APs in a unified manner), suitable for medium and large networks, and can realize layer 2 and layer 3 roaming

When an AP fails, we must first confirm whether the AP is a fat AP or a thin AP. Why?

Because fat and thin APs are configured in different ways

Fat AP: You need to log in to this AP to modify the device

Thin AP: log in to the AC to modify

How to Distinguish Fat APs from Thin APs

Determine whether there is an AC in the environment

Generally, those with AC are thin APs, and those without AC are fat APs.

The default AP mode is thin AP, which can be switched between fat and thin by commands

AP configuration

Ruijie AP configuration

Ruijie fat AP configuration (recommended web interface configuration)

Access Mode Fat AP Configuration

Configuration of fat AP in routing mode (recommended web interface configuration)

Ruijie thin AP configuration

Ruijie Wlan——AC three-layer network side hanging experiment

Ruijie Wlan——AC Layer 2 Networking Side-Hanging Experiment_Ruijie Side-Hanging AC and AP Configuration Steps_Calm Down to Knock Muyu's Blog-CSDN Blog