Seamless Wi-Fi roaming: theory in practice. Seamless WiFi roaming - what is it and why is it needed?! Seamless wi-fi roaming

In the modern business environment, it is difficult to overestimate the role of almost any enterprise information technology, and in lately especially WiFi networks. Wireless communication becomes an excellent assistant when you need to connect a smartphone or tablet, a manager’s corporate phone, a data collection terminal for a warehouse employee, or, for example, a device for accepting payments in a restaurant hall to the Internet. If the territory of your office or enterprise is small, and the load in terms of the number of connected devices does not exceed one dozen - everything is extremely simple, you need to install and configure WiFi router.

But what if you need to cover wireless communication an entire building of a multi-storey hotel, a factory workshop, several halls of a large restaurant, a large office or, for example, a recreation area covering an area of ​​several hectares?

What ways are there to solve this problem?

The company website offers the most advanced solution for large corporate and private WiFi networks - Seamless WiFi

How does this work?

What is the controller used for:

• constant monitoring of the status of access points, the load on them;
• controls signal strength and throughput depending on the number of clients and the nature of their work;
• independently restores areas unserved due to equipment failures by increasing the coverage area from nearby access points;
• provides web authentication and dynamic accounts for the implementation of the so-called " guest access" (for some controllers, options such as printers are available to generate and print temporary user credentials);
• provides a continuous WiFi signal with which you can freely move, for example, with a WiFi phone between the coverage areas of different access points, without interrupting the conversation or observing any interruptions in communication. At the same time, the controller promptly sends a signal to your device from the closest access point.

• provide Internet access to the end client (for example mobile phone or tablet)
• under the control of the controller, the peak load is removed from one point to another

Convenient and beautiful graphical interface

Radio frequency map. Monitor and analyze the surrounding radio environment.

The dashboard gives you a clear picture of the status of your network and displays basic information about each segment.


Great functionality of settings. You can select WiFi channels, frequency spectrum and transmitter power, etc.

From us you can purchase two types of equipment kits for creating seamless WiFi networks

These kits are presented on Ubiquity equipment and are fully compatible with Mikrotik brand routers and switches. It acts as a controller, which, firstly, is convenient in terms of management, and secondly, it removes the load from the main router and is fully responsible for the wireless network at the site. The number of access points is programmatically limited to 20. Wireless points The Ubiquity Unifi AP series is available in two versions - indoors and outdoors. The recommended number of users is up to 50 clients per 1 access point. Depending on the scale of the task, we offer the following options for sale:

These questions are often asked by customers who need complex organization of corporate networks over a large enterprise area.

Based on Wifi, a technology for providing access to corporate computer network in warehouses, offices and production facilities.

As you know, Wifi is wireless standard communications on unlicensed frequencies. The disadvantages of this standard include the limited range of individual access points; this problem is solved by combining individual networks into one multinetwork.

Seamless roaming Users are connected to local, zonal multinetworks from multiple providers. This approach is currently being implemented for heterogeneous networks, for example, to combine WiMAX, Wi-Fi, GSM, CDMA, GPRS, UMTS services.

In the case of WiFi seamless roaming there is a combination of different access points and ensuring the subscriber’s transition between Wi-Fi networks is imperceptible to the user.

In general, seamless wifi roaming ensures uninterrupted connection of subscribers when crossing network boundaries.

Seamless access technology has already been proposed by a number of companies. For example, for heterogeneous wifi networks “seamless roaming” was developed by Cisco, seamless wifi roaming corporate format Actively involved with Motorola, Microtik and Aruba. These are perhaps the most striking offers on the market today, so we will try to compare them on two application tasks, deploying seamless wifi for a warehouse and wifi for hotels.

Basic elements of seamless wifi technology

The development of “seamless” technologies and networks is the main trend of modern technological development.

IN modern networks manufacturers are trying to combine the computing power of the network, both homogeneous (of the same type) and heterogeneous ( different types) infrastructure. This approach is dictated by a wide variety of network standards, including both packet and circuit switched.

For zone networks, such solutions are usually called multiservice networks. For local corporate networks, there are a number of network applications between which it is necessary to ensure coordination and unconditional access without the user noticing.

The technology is implemented using a special software, which stores the client’s IP address in a local or zone network, which simultaneously allows for guaranteed data delivery and uninterrupted traffic when moving between networks.

Thus, uninterrupted operation of applications is also implied.

Currently, the paradigm of “seamless WiFi access” is developing, which is implemented within the framework of virtual local networks VLAN - Virtual LAN.

Seamless wifi roaming Motorola, Microtik, Aruba

If we talk about the proposed technological solutions, then it makes sense to pay attention to three companies operating in this segment - Motorola, Microtik, Unifi, these companies actively compete with each other. Features of technology and idea borrowed from mobile networks, in which such a seamless roaming function is known as the “handover function”.

As a result of the implementation of seamless roaming, access to the network is provided without a single break when moving between networks. The technology is implemented using special network equipment.

Seamless wifi roaming Motorola, Microtik, Aruba offers similar basic functions: default operation in Bridge/Router modes, DHCP recovery function and the presence of DHCP Relay Option 82.

If you need to deploy wifi for hotels, it still makes sense to choose Motorola wifi, which implements:

• access via HTTP / HTTPS, SSHv2, Telnet, SNMP (v2c, v3)
• Captive Portal feature that manages user accounts and encrypts traffic.

If you use Microtik seamless wifi roaming, there are also quite wide possibilities, especially for network equipment available on the market; user authentication is then implemented based on third-party software.

Seamless wifi roaming Unifi is in many ways a cheap and unstable replica that actively offers its equipment for deploying complex Wi-Fi networks. We do not recommend this equipment.

At the same time, I would still like to highlight the functions of Motorola’s seamless wifi, which, using “native” software and a radius server, routes traffic in wireless multinetworks, supports built-in subscriber billing with high-quality authentication and packet encryption (WEP, WPA, WPA2).

This option is especially recommended for corporate networks when it is necessary to provide network access throughout the company, including when you need to install wifi in a warehouse, production or office in a secure mode with reduced risks of traffic interception.

For full-featured multi-service wifi networks, Motorola, using SMART RF, implements the ability to select channels and power levels on the port in WiFi routers Motorola, which allows you to configure and optimize traffic.

Thus, VLAN (virtual local network) allows you to solve a maximum of corporate problems and implement them on the basis of a wireless network.

Seamless roaming wifi mikrotik allows you to organize inexpensive wireless networks, but still significantly inferior to Motorola, despite technologically similar offers.

All companies offer a complete set of hardware equipment that allows you to deploy “large” wifi networks, combining individual access points into one network and providing efficient routing.

At the same time, the optimal amount of functions required in modern corporate networks, implemented only in Motorola wifi, of course, this largely concerns network security and access blocking.

At the same time, for example, motorola wifi seamless roaming can be recommended as an inexpensive solution with a full range of functions for organizing wifi for hotels. Again, this is relevant both for hotel packages and for small hotels that are not particularly concerned about the security of intercepting customer traffic on the internal network.

It can be said about the technologies offered by the listed companies that they continue to develop, updates are released every six months, new firmware hardware equipment. Moreover, all solutions are offered so that users can constantly update their networks, including using legacy equipment that does not interfere with the implementation of new functions.

If we still consider a wireless local network based on the equipment of the proposed companies, then Motorola has offered a much more developed version - Motorola wifi is recommended by our company by default.

802.11R. Fastswitching between points (handover)

Many Wi-Fi manufacturers promise seamless switching between access points using their “brilliant” proprietary protocol.

Despite the beautiful promises, in practice, delays during switching (handover) can be significantly longer than the stated 50-100 ms (switching can take up to 10 seconds when using the WPA2-Enterprise protocol). The fact is that the decision to switch to another access point is always made by the client equipment. Those. Your smartphone, laptop or tablet decides when to switch and how to do it.

Often, proprietary protocols from well-known Wi-Fi manufacturers are based on forced de-authentication of the device when the signal quality deteriorates. Sometimes in Wi-Fi settings points can be set to “roaming aggressiveness” - minimum value signal at which the device will be “thrown out” from the network. Often client equipment does not react correctly to such a “kick in the ass.” The TCP session is terminated and file downloading stops. The connection to mail server, virtual machine. Connecting to the SIP server requires re-authentication.

Quite often, the client device, instead of connecting to a nearby point with a better signal ( pushes him to this decisionWiFicontroller) tries to re-establish the connection with the previous point to no avail. It’s even worse if the device tries to connect to another network from the list of saved ones (for example, a guest network).

But even if the switching process goes according to plan, repeated key exchange (EAP) and authorization on the Radius server (WPA-2 Enterprise) take up significant time.

To solve these problems, the Wi-Fi Association developed the 802.11R protocol. Currently the majority mobile devices it is supported (Apple starting with iPhone 4S, Samsung Galaxy S4, Sony Xperia Z5 Compact, BlackBerry Passport Silver Edition,...)

The essence of 802.11R is that the mobile device knows its own and foreign points by the mobile domain membership signal (MDIE). This signal is added to the SSID beacon signal.

If your iPhone sees a point from its mobile domain with the best signal/noise level, before starting the switching procedure along the existing “thread” it carries out a preliminary authorization with another point in the mobile domain.

Secondly, authorization takes place according to a simplified scenario - instead of a long authorization on the Radius server, the client device exchanges the PMK-R1 key with the Wi-Fi controller. (The initial key PMK-R0 is transmitted only during primary authentication and is stored in the memory of the Wi-Fi controller).

At the moment when another point “retrospectively” authorized the device, the actual handover occurs. Reconfiguring the frequency and channel in a smartphone takes no more than 50 milliseconds. In most cases, it goes completely unnoticed for the user.

When choosing a solution for an office Wi-Fi networks— pay attention to whether the selected equipment supports the open roaming protocol 802.11R, which is understandable for client devices. For example, Edimax Pro equipment fully supports this protocol, so in most cases there are no problems with roaming. However, if your device is old and does not understand the 802.11R protocol, it is possible to adjust the aggressiveness of roaming based on the signal dropping below a threshold - as other Wi-Fi manufacturers do, touting it as an "innovative solution".

802.11 K.Load Balancing in a Wireless Network

In addition to roaming problems, corporate users often have to deal with congestion at one access point. In a classic Wi-Fi implementation, all devices try to connect to the access point with the best signal. Sometimes, as a result of an incorrect location of the point (radio planning error), all the “office inhabitants” are registered at one point, while the rest are “resting”.

Due to uneven load the speed drops significantly local network, because the radio broadcast is one big “hub” where devices “speak in turn.”

To smooth out unevenness and optimally distribute users between points operating on different radio channels, the 802.11K protocol was developed.

802.11K works in conjunction with 802.11R (as a rule, devices that support the “R” standard also support the “K” standard).

If a mobile device “sees” a beacon signal from other points that are in the same mobile domain, the device sends a broadcast request “Radio Measurement Request frame”, which requests information about the current state of other access points within the visibility range:

number of registered users

average channel speed (number of packets transmitted)

how many bytes were transferred in a certain time interval

In the extended specification of the standard, the client's smartphone can query the channel status of other mobile devices connected to a potentially interesting access point that support the 802.11K standard. Devices respond not only to real statistics, but also about the signal/noise state.

Thus, if your smartphone sees 2 or more points within one mobile domain, it will choose not the point with the best signal, but the point that will provide higher connection speed to the local network (less congested).

Reception conditions, the number of users and the load at the point can change dynamically, but using the 802.11K and 802.11R protocols, devices will switch seamlessly and the network load will always be distributed evenly.

Many manufacturers using proprietary protocols implement something similar to 802.11K, where an “overloaded” point forcibly disconnects clients with worse reception conditions or limits maximum quantity simultaneously registered devices and disables registration if the number of clients has exceeded acceptable limits. These proprietary protocols are not as effective, but still prevent the Wi-Fi network from collapsing completely.

How to save on radio planning thanks to802.11K

The use of equipment that supports the 802.11R and 802.11K protocols partially corrects errors made during radio planning. Dynamic protocols with roaming support make it possible to prevent overloads of individual points and distribute the load between points evenly throughout the network.

The WiFi-solutions team recommends that you always do radio planning, but sometimes in small networks, you can arrange the points chaotically. Dynamic protocols will improve Wi-Fi quality and load distribution between channels of neighboring points.

The use of dynamic protocols for seamless roaming reduces overlap areas. Thus, high-quality coverage can be ensured with a smaller number of points. Savings on equipment - up to 25%.

I need some advice. Contact me.

Nowadays, various wireless devices for which high-speed network access is possible only via WiFi are gaining popularity. These are Ipad/Iphone, and other mobile gadgets. When you want to organize WiFi access in an area of ​​30 sq. m., then installing a regular Dlink for 1200 rubles will solve all your problems, but if you have an area >500 sq. m. m. and this is only for one floor, this solution will not work. If you use regular access points or routers, then each router will have its own network name (unique SSID) or the routers will need to be spaced far apart so that coverage areas do not overlap, and this will lead to the emergence of zones with very poor quality reception, or, generally, a missing signal. About six months ago, I encountered the same problem, a solution was found quite quickly - UniFi.

Example of installing WiFi UniFi in a car service center with several buildings.

UniFi provides wireless coverage to the Arcadia School District in California (translation).

UniFi provides wireless access upscale hotels in Peru (translation).

Possibilities WiFi points UniFi:

One network for all WiFi points.

Attractive design.

Easy to install, PoE.

Displays coverage area and access point locations on the administrator display.

Centralized wireless network management.

Guest networks, without access to the local network.

Create temporary passwords for guest users.

Automatic software updates on access points.

High scalability: up to 100 or more points.

Multiple wireless networks with differentiated access rights.

Separation of network user traffic by VLAN.

Fast intranet roaming when switching between access points.

Monitoring user traffic, identifying sources of increased network load.

Large coverage area.

Possibility of generating one-time temporary passwords (relevant for places public use: hotels, cafes, etc.)

Connecting points in repeater mode.

An overview of the capabilities of the UniFi Controller is here.

Implementation of WiFi from Ubiquity in hotels in Peru here (translation).

Hardware controller for Ubiquiti UniFi. UniFi Cloud Key.

What it looks like in practice:

A software controller is installed on one of the network computers, on which all wireless network settings are made.

All settings of points and network parameters are subsequently made through this controller. Below are a couple of screenshots of the settings and appearance.

This is a building plan showing the locations of the points.

Setting up a guest network without access to corporate resources.

Monitoring active clients.

Access point monitoring.

Top view.

The installation and configuration process is extremely simple:

1. Place the points and connect them to the local network; UniFi supports PoE so that you only need an ethernet socket to connect them.

2. Install the software controller on any computer on the network, configure the parameters of WiFi networks, initialize the points, after initialization, the settings from the controller will be applied to the point, and the point will be ready for operation. Even when the controller is turned off, the settings on the points are saved.

When it is necessary to cover large areas with a WiFi signal, improve the performance, reliability and speed of a WiFi network, seamless roaming technology can help us with this. Seamless WiFi is a technology for moving from a single point coverage area WiFi access into the coverage area of ​​another WiFi access point, without significant data loss. You can think of this as a client device handing over from one access point to another. Thus, you can create seamless WiFi coverage over large areas: apartments, restaurants, hotels, warehouses, airports, country houses, stadiums, cities.

The main features when creating seamless WiFi are:

• Calculation of network capacity (power) depending on the expected number of network users.
• Planning WiFi coverage depending on capacity and fault tolerance.
• Inspection of the airwaves for interference, reflections, obstacles and other reasons affecting the propagation of the radio signal.
• Frequency plan planning for better noise immunity and network speed.
• Determination of installation locations for active equipment, taking into account all factors.

List of possible requirements for equipment when organizing seamless WiFi:

1. Possibility of operating WiFi access points in outdoor conditions. It is necessary when covering street areas, as well as when used in rooms with a climate different from room temperature (warehouses, freezers, saunas, swimming pools, etc.)
2. Availability of models with different radiation patterns(sectoral, omnidirectional), for the ability to create complex WiFi coverage schemes.
3. Availability of transmitter power control, to enable the creation of high-capacity networks.
4. Easy to install and secure access points. Possible power supply via PoE, which eliminates the need to lay additional lines to power devices. Compatible with various client devices.
5. Centralized management of all access points. Possibility of managing and billing traffic of subscriber devices. Easy network scalability.

All these characteristics are met by equipment from MikroTik and UBIQUITI, which can provide you with high-quality, seamless WiFi in various conditions: from your apartment to your city.