Q:
We are looking at buying 6 Mikrotik Wifi devices that we plan to configure in bridge mode using the same SSID and channel for all devices to provide complete coverage for the whole office.
We are looking at a similar Cisco based solution which provides functionality to evenly distribute clients across the AP’s, is there a way to distribute clients evenly across the Mikrotik AP’s so that clients don’t all connect to one AP?
A:
It is problematic and highly complex to do – only a few ‘advanced’ vendors have such a feature, and the implementations often require installation of client-side software to make it work properly.
The problem is that WiFi protocol is limited by legacy design ‘feature’ as an autonomous system – i.e. all devices on the network make their own decisions on how to behave, and there is no centralised controller possible in a standard open WiFi network (not even the AP, and not even a proprietary ‘controller’) The way a client device (laptop, tablet, smartphone, etc) connects to the wireless network is determined 100% by the client wireless chipset and device drivers – there is no way to control it without installing a proprietary device driver or middleware software on the clients.
Therefore, any ‘wireless controller’ solution that attempts to control what AP a client connects to is really ‘fudging’ the wireless network to make the client ‘believe’ that it is connecting to some AP when it is actually connecting to some other. Again, since the client is ‘autonomous’, not all clients behave the same way, and so some will behave badly when such a controller is present, and some simply don’t work at all.
MikroTik RouterOS offers a few features that help to distribute clients across a wider area covered by intermeshing APs. Here are some of the options:
1. Limit to the maximum number of clients allowed to connect. In the case of an application like a large auditorium with 4 APs installed that has up to 200 audience, routerOS allows a limit of 50 connected clients to each AP – that way, when one AP reaches the limit, it refuses to accept any more connections, thus forcing the client to try one of the other available APs. The downside of this approach is that it does not assure ‘even distribution’ between APs, so if there are only 50 users connecting to the network, it is not impossible (though unlikely!;) that all 50 might connect to the same AP
2. Limit /minimum/ signal strength of clients allowed to connect. This feature prevents a client from ‘sticking’ on to one AP even if it has moved to another location where connection to the AP is poor, and a much better signal (even with same SSID) is right nearby. (iPhone is a classic example of that behaviour!) A minimum signal limit will cause an AP to drop a client connection when it moves too far away and then refuse attempts to reconnect, forcing that client thus forcing that client to seek another AP to connect to, and so effectively ‘roam’ between AP devices. The downside of this approach is that the re-association from one AP to the next may take a few ms longer that allowing the client to just re-train at a lower speed to the same AP.
3. Dynamic WiFi mesh. MikroTik devices support a proprietary ‘HWMP+’ meshing protocol that is similar to WDS with the additional feature of automatically adjusting wireless peer links to utilise the most efficient paths through the network. WDS-type mesh implementations can present a consistent wireless cell to the client, allowing it to move through the network with relative ease. There are still some problems related to behaviour of ‘sticking’ to a single AP, but when all devices have same SSID, are on same layer2 broadcast domain, and have consistent frequency channels, the delay times moving from one unit to another are minimised. This method is best for when there is no opportunity to connect each AP to a wired network point. The downside is that the throughput capacity of the network is limited to a single wifi network (i.e. if a WiFi AP is capable of, say, 480Mbps 802.11ac, a mesh is limited to sharing that 480M between all connected clients – whereas one of the other methods above will offer 480mbps to EACH CELL, thus will evenly distributed clients, the total throughput is increased but the same multiple of APs present (assuming good channel separation)
MikroTik RouterOS also offers CAPsMAN wireless controller which allows a single point of administration to manage all properties of all APs inside a wireless network – manageable properties include SSIDs (including multiple virtual SSIDs) and wireless passwords, access controls, connection signal and number controls, frequency channels and transmit levels and much more.
An additional feature offered by routerOS is possibility to implement multiple ‘virtual AP’ – a virtual APs are additional SSIDs that are broadcast by the same physical wireless interface which can be selected and connected to in just the same way as any other /physical/ AP. Virtual AP can have different subnet, different password (including EAP) and can even have different traffic priority QoS levels. We use this feature to present EduRoam access throughout the Geelong Free WiFi network as a great example.
To summarize, although RouterOS does not have any feature comparable to Cisco WiFi controller, it does offer many features that provide some advanced controls over wireless client behaviour to address some of the most typical issues encountered with this types of larger scale networks. Due to the fact that MikroTik hardware is cheaper than most other advanced WiFi systems hardware, there is no costly wireless controller hardware to buy, and there is no ongoing proprietary software licensing fees, network operators need to seriously consider whether the significant additional expense of deploying alternative solutions will really deliver the comparable improvement in performance and usability.
MikroTik systems are definitely capable of delivering a stable and high performance wireless system as significantly lower price than most other vendor equipment. As an example, our public access WiFi networks built in Geelong. Horsham, Hobart and other locations has been delivered at an average cost of about $2500 per Hotspot – similar projects awarded to other vendors for cities of Melbourne, Ballarat and Bendigo have been costed to around $6500 per Hotspot!
I am actually aware that I have not answered your question with a simple ‘yes or no’ response, but hope that you will find a more detailed reply has some additional detail that will allow you to make your decision with ore clarity and certainty!
If you have some further questions, would like to seek clarification or make comment on this article, you are welcome to contact us!