Seamless wifi roaming is an effective combination of several access points to the wireless Internet into a continuous system under the control of their broadcast by one central device-controller. Correctly installed and configured equipment allows you to use the global network in any area on an ongoing basis without partial or complete signal interruption. Depending on the goals set, UmkaPro is always ready to design, buy the necessary technical means, mount and configure seamless Wi-Fi at any facility in Moscow.
Seamless WIFI working principle
Multiple stand-alone points can be set up to cover a large area with wireless Internet access. However, in this version, you will have to constantly switch, moving around the territory. This is not practical and inconvenient at all. It was to create a single network in which the signal is not lost when switching between access points, and seamless wifi roaming was developed.
The essence of its work lies in the simultaneous operation of several access points. At the same time, their broadcasting is controlled by one controller, which:
- monitors the load on each access point;
- adjusts the signal, as well as the bandwidth, depending on the number of users;
- guarantees high-speed roaming, through which you can freely move around the territory without interrupting data transmission. The controller constantly sends a signal to a specific device from those access points that are closest.
What is seamless wifi built on
Years of work in this direction allow us to single out the following types of equipment, which is the most successful modern option for equipping private houses, offices, shopping malls and other types of facilities:
- Seamless roaming wifi Mikrotik CAPsMAN is a very reliable and relatively inexpensive piece of equipment that can cope with almost any task.
- Seamless wifi roaming Ubiquiti UniFi is the most versatile, uninterrupted solution that provides a consistent level of connectivity in any area.
- Seamless roaming wifi Zyxel is a more expensive option of equipment, which, in addition to the standard controller, is also represented by special access points with controller functions.
Regardless of the area of the facility being equipped, our company's specialists are always ready to design and install Ubiquiti, Zyxel or Mikrotik wifi roaming with high quality. Years of work in this direction allow us to guarantee the impeccable quality and efficiency of the installed system.
In this article, we will learn how to create a single seamless WiFi network on MikroTik / Mikrotik routers. Where can this come in handy? For example, in all sorts of cafes or hotels, where one wi-fi router is not enough to cover all premises and access the Internet, and with a large number of access points, various kinds of problems constantly arise: the connection is constantly lost on laptops, and mobile devices do not switch to nearest access point.
The solution to this situation is seamless roaming of a WiFi network or handover, which we can get thanks to the CapsMan functionality from several Mikrotik routers, one of which will be a WiFi controller, and the rest will be access points controlled by this controller.
The first thing to do is update to the latest software version. The firmware can be downloaded from the official website. Next, going into the MikroTik interface, drag it to the Files section and reload the router. Along with the firmware, you also need to download the Wireless CAPs MAN package, drag it to the same place and reboot. After the actions taken, you can proceed to the setting.
Let's start with the controller. Open the CAPsMAN section by clicking the corresponding button in the main menu. In the Interfaces tab, press the Manager button (enable controller mode) and in the window that appears, check the Enable box, save OK. After that, go to the Configurations tab.
The configuration settings will apply to all access points connected to the controller. We press the blue cross and in the Wireless tab specify the configuration name (3), the wireless network mode (4), the network name (5), and also turn on all wireless antennas to receive and transmit (6), save (7) and go to the Channel tab ...
Here we indicate the frequency (2), the broadcast format of the wireless network (3) and the channel (4). Save (5) and go to the Datapath tab.
Here we only need to check the Local Forwarding checkbox - this will transfer traffic control to the access points. It remains to fill in the last Security tab.
In the security section, select the authentication type, encryption method and password for the wireless network, click OK.
After we have created the configuration, we move on to the next item - deployment. In the same CAPsMAN section, select the Provisioning tab (1) and click the blue cross. The Radio MAC field (2) allows you to select a specific access point to which our deployment will refer. We leave it at the default so that the deployment applies to all APs. In the next field, Action (3), select createdynamicenabled, since we have a dynamic interface. In Master Configuration (4), specify the name of the configuration created above.
We are done with the CAPsMAN section, go to the Wireless section (1). In the Interfaces tab, click the CAP (3) button, check the Enabled (4) box, select the wlan1 interface and specify the ip-address of our main router, which is also a controller.
If we did everything correctly, then two red lines will appear in the Interfaces tab, which indicate that the wi-fi adapter has connected to the controller and has taken over all the necessary settings.
This completes the configuration of the main router controller, and this network can be used to create a telephone network and connect to an office PBX
Setting up access points that will connect to the controller via an Ethernet cable is pretty straightforward. They also need to be flashed to the latest version and CAPs MAN installed. Next, we combine all the ports and the wi-fi interface into one Bridge in the section of the same name.
The next step in the Wireless section is the same as on the controller, except that instead of the IP address in the CAPs MAN Addresses, we indicate the Bridge created on the access point in the Discovery Interfaces field. After the performed manipulations, the access point will receive the settings from the controller and will distribute wi-fi (the same two red lines should appear in the Interfaces tab).
What is seamless wifi roaming?
Seamless roaming is when access points in your network are controlled by a special controller wireless network. A controller in a seamless network can be either one of the routers or access points, or a separate device that monitors the general state of the air, the load on each of the wireless access points and the signal level between clients and APs. When the signal degrades between the client and the access point, the controller "forcibly flips" the client to a more suitable AP. The fact is that in a regular network, a client (phone, laptop, tablet) will until the last "cling" to the AP's MAC address (WLAN interface address), and not to its SSID (name), which leads to negative consequences when moving around the building. The controller will continuously monitor the load of the access points and the quality of the signal between the base station and the client hundreds of times per second. In such networks, when moving from one end of the room to the other, the access point that is closer and not loaded will work. It is very useful for business and shopping centers, large shops, government agencies, hospitals and educational institutions... Load sharing technology will be needed when there are large numbers of people in places such as conference rooms or amusement parks.
Looking for a cost-effective, automatic client switching solution for your $ 150 home?
For 2020, affordable mesh kits appear, which are no longer a shame to install and be sure of the result. It is a pity that we are talking about several manufacturers, but still there is a light at the end of the tunnel. The budget niche includes:
Asus, TP-Link, Tenda, Ubiqiuty, Mikrotik, Zyxel and Xiaomi. Almost each of these manufacturers has several types of access points for the street and the house, for walls or ceilings, for a separate wifi network controller or controller is one of the access points.
And now, specifically, with numbers. They drove.
Seamless Wi-Fi systems from Asus.
The easiest wireless network option without controller, but with automatic selection of the best access point, it may consist of several of the most common ASUS routers. For these purposes, the following models are suitable: RT-N11P, RT-N66U, RT-AC55U, RT-AC66U and newer "P" series routers. They must be connected to each other with a wire - twisted pair of category 5e and higher, as shown in the picture below. On these models, there is only the option to configure Roaming Assist, which is the only way on this type of device. The following will happen: if the signal level is low, after a certain time the router will disconnect it from the network and the client will reconnect to the point with the best signal. It should be understood that this type of wireless network configuration is not seamless, but rather voluntary-compulsory, with a short-term, but complete loss of the connection. When installed correctly, it will allow you to save a lot, compared to even the simplest networks with an access point controller, but in practice this works with difficulties for the user, especially when he is in an area of uncertain reception from both points, which in turn can start to "football" our a poor user and the Internet will not work for him plainly. Please remember this. Routers RT-AC68U and older already have a proto version of Mesh networks from such access points, but I do not like the price in relation to the result obtained, it is better to take the Lear access points sharpened for this business. They will be discussed below.
Now let's look at the most optimal option, this is MESH networks from Asus. This set is called Lyra and let's see what it can give us, but it can give us much more than our OGV, joke, 350 - 450 megabits it can give us over the entire area and you can move anywhere without breaks.
Your goal is to make a high-quality wireless wifi network with roaming?
For our clients, we have professional solutions for wifi networks with the highest characteristics in terms of reliability, speed and level of security. In such cases, the network consists of a number of access points interconnected by a twisted pair through switches and an access point controller. The functions of a wi-fi network controller include:
- monitoring the load on each individual access point and its distribution.
- monitoring the quality and level of the signal between the access point and the client.
- centralized management of all access points in the network.
- providing instant switching of the client from one access point to another, without losing the connection to the Internet.
Such a network can be scalable and gradually expand.
For a hotel, large office, cottage settlements, one access point, even the most productive and long-range one, is not enough. The distribution of access points gives a much better result and is scalable. The figure above illustrates the coverage area of seven APs and one controller configured for seamless roaming.
If your goal is to make sure that when you move from one access point to another, the connection to the Internet does not disappear, then we can help you with the search and purchase of equipment for a wifi network with roaming.
To organize a fast and loaded wireless network in the whole building, the functionality of ordinary wifi routers will not be enough due to the fact that the decision to "fall off" from the access point is taken by the end device itself and the router will not help here. It turns out that the same smartphone or tablet will cling to the access point until the last, taking into account the fact that in the list of networks known to it there will be an access point with a hundred percent signal.
There are two good ways to make a mesh like this. and a lot of bad ones :) Consider the good ones, but I would not recommend messing around with the bad ones.
1) WiFi network with a certain number of access points interconnected by a switch and controlled by a special controller of wireless access points in the local network. This option is the most reliable, unpretentious and of course expensive. A network of this type using the example of Zyxel equipment will cost in the region of $ 2000-3000 for an area of 10000m 2 (100x100m). For country houses, seamless roaming will be cheaper; 1000-1500 $ for a large house and a personal plot. Such networks are able to withstand heavy loads and evenly distribute users across access points, depending on the load on each of them. These networks are easy to administer and are well suited for commercial properties, hotels, restaurants, parks and similar public spaces.
2) A well-proven method is to use the Roaming asist function. This method is the most cost-effective. With four ASUS RT-AC66U routers, you can get an analogue of seamless wifi roaming and a wireless network speed throughout the house and the surrounding area of 300-500 megabits per second on the 802.11ac standard. with automatic switching between access points. In both cases, wifi routers are connected with a wire.
Budget and professional solutions in our store with installation and customization.
We understand roaming technologies (Handover, Band steering, IEEE 802.11k, r, v) and conduct a couple of visual experiments that demonstrate their work in practice.
Introduction
Wireless networks of the IEEE 802.11 group of standards today are developing extremely rapidly, new technologies, new approaches and implementations appear. However, as the number of standards grows, it becomes more and more difficult to understand them. Today we will try to describe several of the most common technologies that are referred to as roaming (the procedure for reconnecting to a wireless network), and also see how seamless roaming works in practice.
Handover or "client migration"
Once connected to a wireless network, a client device (be it a smartphone with Wi-Fi, a tablet, laptop or PC equipped with a wireless card) will maintain a wireless connection if the signal parameters remain at an acceptable level. However, when the client device moves, the signal from the access point with which the connection was originally established may weaken, which sooner or later will lead to a complete impossibility of data transmission. Having lost connection with the access point, the client equipment will select a new access point (of course, if it is within reach) and connect to it. This process is called handover. Formally, handover is a migration procedure between access points, initiated and performed by the client itself (hand over - "transfer, give, give up"). In this case, the SSIDs of the old and new points do not even have to match. Moreover, the client can fall into a completely different IP subnet.
To minimize the time spent on reconnecting a subscriber to media services, it is necessary to make changes both to the backbone wired infrastructure (make sure that the client's external and internal IP addresses do not change) and to the handover procedure described below.
Handover between access points:
- Determine the list of potential candidates (access points) for switching.
- Set the CAC-status (Call Admission Control - control of the availability of calls, that is, in fact, the degree of congestion of the device) of the new access point.
- Determine the moment to switch.
- Switch to new access point:
In IEEE 802.11 wireless networks, all handover decisions are made by the client side.
Source: frankandernest.com
Band steering
Band steering technology allows a wireless network infrastructure to transfer a client from one frequency band to another, usually a forced client switch from the 2.4 GHz band to the 5 GHz band. Although band steering is not directly related to roaming, we decided to mention it here anyway, as it is related to client device switching and is supported by all of our dual-band APs.
When can it be necessary to switch a client to a different frequency range? For example, such a need may be associated with the transfer of a client from an overloaded 2.4 GHz band to a more free and high-speed 5 GHz band. But there are other reasons as well.
It should be noted that at the moment there is no standard that strictly regulates the operation of the described technology, so each manufacturer implements it in its own way. However, the general idea remains roughly the same: access points do not advertise the SSID in the 2.4 GHz band to a client performing an active scan, if activity of this client at a 5 GHz frequency has been noticed for some time. That is, access points, in fact, can simply keep silent about the presence of support for the 2.4 GHz band, if it was possible to establish the availability of client support for the 5 GHz frequency.
There are several modes of band steering operation:
- Force connection. In this mode, the client, in principle, is not informed about the availability of support for the 2.4 GHz band, of course, if the client has support for the 5 GHz frequency.
- Preferred connection. The client is forced to connect to the 5 GHz band only if the RSSI (Received Signal Strength Indicator) is above a certain threshold, otherwise the client is allowed to connect to the 2.4 GHz band.
- Load balancing. Some clients that support both frequency bands connect to the 2.4 GHz network, and some to the 5 GHz network. This mode will not overload the 5 GHz band if all wireless clients support both frequency bands.
Of course, customers supporting only one frequency band will be able to connect to it without any problems.
In the diagram below, we tried to graphically depict the essence of the band steering technology.
Technologies and standards
Let's now return to the very process of switching between access points. In a typical situation, the client will maintain the existing association with the access point as long as possible. Exactly as long as the signal level allows it to be done. As soon as a situation arises that the client can no longer maintain the old association, the switch procedure described earlier will start. However, handover does not happen instantly, it usually takes more than 100 ms to complete, which is already a noticeable amount. There are several radio resource management standards of the IEEE 802.11 working group aimed at improving wireless reconnection times: k, r, and v. In our Auranet line, 802.11k support is implemented on the CAP1200 access point, and in the Omada line on the EAP225 and EAP225-Outdoor access points, the 802.11k and 802.11v protocols are implemented.
802.11k
This standard allows a wireless network to communicate to client devices a list of neighboring access points and channel numbers on which they operate. The generated list of neighboring points makes it possible to speed up the search for candidates for switching. If the signal of the current access point weakens (for example, the client is removed), the device will look for neighboring access points from this list.
802.11r
Version r of the standard defines the FT - Fast Transition (Fast Basic Service Set Transition) function to speed up the client authentication procedure. FT can be used when switching a wireless client from one access point to another within the same network. Both authentication methods can be supported: PSK (Preshared Key) and IEEE 802.1X. Acceleration is carried out by storing encryption keys on all access points, that is, the client does not need to go through the full authentication procedure when roaming with the involvement of a remote server.
802.11v
This standard (Wireless Network Management) allows wireless clients to exchange service data to improve the overall performance of the wireless network. One of the most used options is BTM (BSS Transition Management).
Typically, a wireless client measures its connection to an access point to make a roaming decision. This means that the client has no information about what is happening with the access point itself: the number of connected clients, device boot, scheduled reboots, etc. Using the BTM, the access point can send a request to the client to switch to another point with better working conditions , even with a slightly worse signal. Thus, the 802.11v standard is not directly aimed at speeding up the switching process of a client wireless device, but when combined with 802.11k and 802.11r, it provides faster program performance and improves the convenience of working with Wi-Fi wireless networks.
IEEE 802.11k in detail
The standard extends the capabilities of Radio Resource Management (RRM) and allows 11k-enabled wireless clients to query the network for a list of potential candidate hotspots. The access point informs clients of 802.11k support through a special flag in the Beacon. The request is sent in the form of a management frame called an action frame. The access point also responds with an action frame containing a list of neighboring points and their wireless channel numbers. The list itself is not stored on the controller, but is generated automatically upon request. It is also worth noting that this list depends on the location of the client and does not contain all possible wireless access points, but only neighboring ones. That is, two wireless clients geographically located in different locations will receive different lists of neighboring devices.
With such a list, the client device does not need to scan (active or passive) all wireless channels in the 2.4 and 5 GHz bands, which reduces the use of wireless channels, that is, free up additional bandwidth. Thus, 802.11k allows you to reduce the time spent by the client for switching, as well as improve the process of choosing an access point for connection. In addition, no additional scans are required to extend the battery life of the wireless client. It is worth noting that access points operating in two bands can inform the client about points from an adjacent frequency band.
We decided to visually demonstrate the operation of IEEE 802.11k in our wireless equipment, for which we used an AC50 controller and CAP1200 access points. As a source of traffic, we used one of the popular instant messengers with support for voice calls, running on the Apple iPhone 8+ smartphone, knowingly supporting 802.11k. The voice traffic profile is shown below.
As you can see from the diagram, the used codec generates one voice packet every 10 ms. The noticeable spikes and dips in the graph are due to the slight variation in latency (jitter) that is always present in Wi-Fi based wireless networks. We configured traffic mirroring to which both access points participating in the experiment are connected to. Frames from one access point went to one network card of the traffic collection system, frames from the second - to the second. In the received dumps, only voice traffic was sampled. Switching delay can be considered the time interval from the moment of traffic loss through one network interface until it appears on the second interface. Of course, the measurement accuracy cannot exceed 10 ms, which is due to the structure of the traffic itself.
So, without enabling support for the 802.11k standard, switching the wireless client took an average of 120 ms, while activating 802.11k allowed this delay to be reduced to 100 ms. Of course, we understand that although the switching latency was reduced by 20%, it still remains high. Further reduction in latency will be possible with the combined use of the 11k, 11r and 11v standards, as is already implemented in the home series of wireless equipment.
However, 802.11k has another up its sleeve: timing to switch. This possibility is not so obvious, so we would like to mention it separately, demonstrating its work in real conditions. Typically, the wireless client waits until the last, maintaining the existing association with the access point. And only when the characteristics of the wireless channel become completely poor, the procedure for switching to a new access point is started. Using 802.11k, you can help the client with the switch, that is, offer to make it earlier, without waiting for significant signal degradation (of course, we are talking about a mobile client). Our next experiment is devoted to the moment of switching.
Qualitative experiment
Let's move from the sterile laboratory to the real customer's site. The room was equipped with two 10 dBm (10 mW) APs, a wireless controller and the necessary supporting wired infrastructure. The layout of the premises and the location of the access points are presented below.
The wireless client moved around the room making a video call. First, we turned off support for the 802.11k standard in the controller and set the places where the switch took place. As you can see from the picture below, this happened at a considerable distance from the "old" access point, near the "new" one; in these places the signal became very weak, and the speed was barely enough to transmit video content. There were noticeable lags in voice and video when switching.
Then we turned on 802.11k support and repeated the experiment. The switchover now took place earlier, in places where the signal from the "old" access point was still strong enough. There were no lags in the voice or video. The switching point has now moved approximately halfway between the access points.
In this experiment, we did not set ourselves the goal of elucidating any numerical characteristics of switching, but only qualitatively demonstrating the essence of the observed differences.
Conclusion
All described standards and technologies are designed to improve the client's experience of using wireless networks, make it more comfortable to work, reduce the influence of annoying factors, and increase the overall performance of the wireless infrastructure. We hope that we were able to demonstrate clearly the benefits that users will receive after implementing these options in wireless networks.
Is it possible to live in an office without roaming in 2018? In our opinion, this is quite possible. But, having tried once to move between offices and floors without losing the connection, without having to re-establish a voice or video call, without being forced to repeat what was said or ask again, it will no longer be realistic to refuse.
P.S. but this is how you can make seamlessness not in the office, but at home, which will be discussed in more detail in another article.
