Distinguishing Fat APs & Fit APs Before Networking

Posted on September 5, 2020
September 30, 2020

With a wireless access point (AP), be it at homes or in corporate offices, one can easily connect multiple devices for wireless connections with better convenience and higher flexibility. As one of the key parts for building wireless networks, the choice of access points is crucial based on users' various needs. Fat APs and fit APs with diverse features can meet different networking deployment. This article will make a comparison between these APs for your wiser selection.

Explanations for Fat AP & Fit AP

The most visible difference between a fat AP and a fit AP (thin AP) lies in the WAN port. A fat AP possesses the WAN port that is easy to tell. In addition, the fat AP that has both WAN and LAN ports can support security functions such as DHCP server, DNS, MAC address cloning, VPN access, and firewall. As a network device that can work independently, the fat AP can implement dialing, routing, and some other functions. Typically, fat APs are used as stand-alone access points that can operate in the absence of any controller device.

Fat AP Networking Mode

Namely, the "slim version of AP" is intended to reduce the complexity of the hardware of the original APs. Thin AP, without an own complete operating system, removes the routing, DNS, DHCP server, and many other loading functions and only retains the wireless access part. As a component of wireless LAN, fit/thin AP cannot work independently and requires cooperating with AC management. Actually, thin APs/fit APs are quite common in daily use, which is equivalent to a wireless switch or hub, providing only one wired/wireless signal conversion and wireless signal receiving/transmitting function.

Fat AP Networking Mode

Comparison Between Fat AP & Fit AP in Networking

The demand for wireless networks in enterprises is steadily rising, which requires powerful wireless devices. Therefore, the number and size of the wireless devices are increasing exponentially. Two main solutions for business networking: Option 1: distributed WLAN networking mode with fat APs plus wired switches. Option 2: centralized WLAN management mode with thin APs plus wireless controllers. The following part will make an analysis of these two kinds of solutions in five major aspects.

Wireless Roaming

If the user goes from the coverage area of a fat AP to the coverage area of another fat AP, the device will reconnect the new fat AP with a strong signal, re-authenticate, and re-acquire the IP address. Network disconnection will happen accordingly. However, things will be different if it is a thin AP. The signal is automatically switched, and there is no need to re-authenticate, and re-acquire the IP address when adopting a thin AP. That is to say, the signal and the network are always connected online, which may help to avoid the disconnection issue. A thin AP network can perform seamless roaming across Layer 2 and Layer 3.

Automatic Load Balancing

When many users are connected to the same fat AP, the fat AP cannot automatically perform load balancing to allocate users to other fat APs with lighter loads. Consequently, fat APs have higher risks of network failures due to heavy load. In the AC + fit AP configuration, with multiple users connected to the AP at the same time, the AC will function automatically to allocate users to other APs with lighter load according to the load balancing algorithm, which minimizes the network malfunctions and improves the performance of the entire network.

Safety Certification

Most of the simple fat AP networks only have a single authentication mode with pre-shared keys. The network access security cannot be guaranteed, and unified authentication management cannot be performed. The thin AP accepts the management of the wireless controller and is responsible for simple functions such as encryption and decryption of 802.11 messages, with illegal AP detection and processing mechanisms.

Management and Maintenance

Fat APs cannot be centrally managed. They need to be configured separately and the configuration work is troublesome. Just imagine that you have a hundred APs in your system. Then every single new AP device needs to be configured one by one. When maintaining, you need to log in to the AP device one by one to view the AP running status and user statistics. For upgrading, you need to upgrade the software manually step by step. Forget about this time-consuming and labor-intensive solution, fit AP is more intelligent in centralized management. "Fit AP + AC" mode doesn't need a separate configuration. The advantages of this kind of centralized management are more outstanding especially in the case of a large number of APs.

Network Applications for Fat AP & Fit AP

As mentioned before, the downsides of fat APs lie in relative inconvenience, instability, insecurity, and complexity. Besides, fat APs tend to be built on powerful hardware and require complex software which adds to costs. While a fit AP/AC installation is easier, which simplifies the AP construction with a significant change in costs. But the controller generally needs to be based on a more powerful hardware platform in fit AP mode than fat AP mode due to the higher workload.

Therefore, fat APs that work independently without AC coordination are normally used in small-sized wireless network constructions like homes and small offices that only cover a small number of users. Compared with fat APs, thin APs with more advantages in WLAN networks are unmatched by fat APs. "AC + AP" mode tends to be the de facto solution for most enterprises nowadays. Besides, thin/fit APs can also be applied in medium and large-scale wireless network constructions like shopping malls, supermarkets, hotels, attractions, etc., where multiple APs are combined with AC products to create a larger wireless network coverage.

Future Trend: Wireless Access Point Combining Fat & Fit Feature

With the increasing demand for wireless coverage, the performance requirements of wireless APs are also higher and higher. The simple "fat AP" and "thin AP" will no longer meet the complex and flexible needs. Between the fat AP and fit AP, there is a compromise. Combining the advantages of both fat and fit APs, the "fat and thin integrated wireless AP" that can switch flexibly between fat & thin modes stands out.

Either deployed as standalone AP (fat mode) or managed AP (fit mode), the AP will detect the operation mode automatically without extra effort on firmware upgrade. All the user needs is to change the working mode and to add ACs for fit mode. This will not only realize a smooth transition with simpler installations but also provide a cost-effective solution. Therefore, this kind of AP solution with a hybrid management model is fit for network upgrading from small-scale to large-scale networks.

At present, these access points that support hybrid management modes are gaining more popularity in enterprise networks. The enterprise-grade APs, most support Wi-Fi 6 standard at present, can not only support flexible switching over the fat and fit modes according to the networking requirements but also meet the future development requirements. When there are few APs, the network managers can adopt the fat mode for easy, independent network establishment. For large-scale networks, these APs can operate at fit mode and work with the ACs to allow centralized management of all the APs and other aspects such as security, traffic management, QoS, and IP management.