Lab 05-01 · Wireless basics and your radio name¶

How many times have you connected to WiFi today? Home, the bus, the school, a friend's flat... Your phone did it without asking you anything. But look at the list of networks your phone sees: MOVISTAR_8A21, DIRECT-roku-447, iPhone de Laura, eduroam. Dozens of invisible radios, all talking at the same time in the same air. How do they not trip over each other?

Today you will open the radio of a MikroTik router, connect it as a client to the teacher's WiFi, and give it a name so the teacher can tell which of the twenty routers in the room is yours.

WiFi is radio¶

Our analogy for the whole lab: FM radio in a car.

WiFi is a family of standards that lets devices exchange network data using radio waves instead of a cable. The standards are written by the IEEE under the number 802.11; "Wi-Fi" is the brand of the Wi-Fi Alliance, which certifies that devices follow them.

When you tune a car radio, you pick a waveband (FM or AM) and then a station inside it (for example 98.0 MHz). WiFi works the same way:

The big difference: a car radio only listens. A WiFi station also talks back, on the same channel. That is why WiFi gets slow when many devices share one channel: they have to take turns.

The standards: from 802.11b to WiFi 7¶

Each new 802.11 standard added speed. Since 2018 the Wi-Fi Alliance also gives them simple generation numbers.

Channels: 2.4 GHz is crowded¶

The 2.4 GHz band is narrow: in Europe it holds 13 channels, each 5 MHz apart (channel 1 = 2412 MHz, 6 = 2437 MHz, 11 = 2462 MHz, 13 = 2472 MHz). But a WiFi transmission is 20 to 22 MHz wide, so it spills over its neighbours. Only channels 1, 6 and 11 do not overlap: three APs on 1, 6 and 11 can share a room without interfering. Channel 14 exists only in Japan, and the USA uses only 1–11.

flowchart LR
    subgraph B24["<b>2.4 GHz band</b> (2400-2483.5 MHz)"]
        C1["<b>ch 1</b><br>2412 MHz"]
        C6["<b>ch 6</b><br>2437 MHz"]
        C11["<b>ch 11</b><br>2462 MHz"]
    end
    C1 -. "25 MHz apart:<br>no overlap" .- C6
    C6 -. "25 MHz apart:<br>no overlap" .- C11

The 5 GHz band is much wider: channels 36–64 (5180–5320 MHz), 100–144 (5500–5720 MHz) and 149–165 (5745–5825 MHz), depending on the country. Channels can be glued together into wider ones (channel width 20, 40, 80 or 160 MHz): wider is faster but uses up more of the band. In a classroom with twenty routers, narrow 20 MHz channels are the polite choice.

6 GHz (WiFi 6E and 7) is the newest band: in Europe 5945–6425 MHz was opened to WiFi in 2021. Our hAP ax² has no 6 GHz radio, so we will not use it.

Country rules and DFS¶

Radio is a shared, public resource, so every country decides which channels and how much power are legal. That is why RouterOS asks for a country: it then hides illegal channels and caps the transmit power.

Some 5 GHz channels are also used by radars (weather and military). On those channels (in the EU, 52–140) a WiFi AP must use DFS (Dynamic Frequency Selection): before transmitting it listens for 60 seconds (10 minutes on the weather-radar channels 120–128), and if it ever hears a radar it must jump to another channel. Channels 36–48 need no DFS, which is why we use them for quick classroom labs.

Access point and station¶

An access point (AP) creates a WiFi network and lets clients join it. A station is a client that joins an AP.

Your phone is always a station. Your home router is an AP. A MikroTik router can be either: in this module, your router starts as a station of the teacher's AP (it gets its Internet over WiFi, like a phone), and in Lab 05-03 it becomes an AP too.

To join a network a station needs three things: the band to listen on, the SSID to look for, and the password (the security settings; more in Lab 05-03). It does not need a channel: it scans all the channels of the band (its scan list) until it hears the SSID.

Two WiFi menus in RouterOS 7¶

MikroTik routers have two different WiFi drivers, with two different menus. The course slides (made with older routers) show the old one.

Since RouterOS 7.13 both drivers are separate packages, and they cannot be active at the same time. Settings in the new menu are grouped in reusable profiles: security, channel, configuration and datapath (think of them as presets you then assign to a radio).

The scenario¶

The teacher's router (class-ap) broadcasts the network ClassAP on 2.4 GHz, channel 1. Your router r1 joins it as a station with its 2.4 GHz radio (wifi2 on the hAP ax², wlan1 on the hAP ac²; on another model, check which interface is which band in WiFi → Radios), gets an address 10.0.0.x by DHCP, and shares that Internet with your laptop on the LAN.

flowchart LR
    NET["<b>School network</b><br>Internet"] --- CAP
    subgraph CAP["<b>class-ap</b> (teacher)"]
        CAPW["AP <b>ClassAP</b><br>2.4 GHz, ch 1<br>10.0.0.1/24"]
    end
    CAPW -. "WiFi 2.4 GHz<br>WPA2/WPA3" .- R1W
    subgraph R1["<b>r1</b> (your router)"]
        R1W["wifi2 / wlan1<br><b>station</b><br>DHCP 10.0.0.x"]
        BR["bridge1<br>192.168.88.1/24"]
    end
    BR -- "cable to ether2" --- PC["<b>Your laptop</b><br>192.168.88.x (DHCP)"]

Start the lab¶

Download the lab files and unzip them: 05-01-radio-name.zip. Open a terminal inside the 05-01-radio-name folder.

Every lab of this module ships two starting files: initial/r1.rsc (hAP ax², WiFi menu) and initial/r1-legacy-wireless.rsc (hAP ac², legacy menu). Pick yours.

1. Plug your laptop into ether2, open WinBox and connect to the router (by MAC address if it has no IP yet).
2. Drag the .rsc file into Files (or scp r1.rsc admin@192.168.88.1: from a terminal).
3. Open New Terminal and reset the router, telling it to run your file after the reboot:

/system reset-configuration no-defaults=yes skip-backup=yes run-after-reset=r1.rsc

/system reset-configuration no-defaults=yes skip-backup=yes run-after-reset=r1-legacy-wireless.rsc

The router reboots (about one minute). The admin password goes back to the factory one (empty on older routers, the one on the sticker on newer ones). Reconnect WinBox to 192.168.88.1.

The teacher loads initial/class-ap.rsc on the class router the same way.

Step 1 · Check that you are a station of ClassAP¶

Why: before changing anything, prove the WiFi link works and learn where to read its state.

WinBox: WiFi → WiFi Interfaces (legacy: Wireless → WiFi Interfaces), then IP → DHCP Client.

/interface wifi print
/interface wifi monitor wifi2 once
/ip dhcp-client print

/interface wireless print
/interface wireless monitor wlan1 once
/ip dhcp-client print

Expected: the 2.4 GHz interface is running (flag R), monitor shows that the station is connected (legacy: status: connected-to-ess; WiFi: a state line saying it is running as a station), the SSID ClassAP, the channel (2412 MHz) and a signal like -45 dBm. The DHCP client is bound to an address 10.0.0.x.

Then test the Internet: ping 10.0.0.1 and ping www.mikrotik.com.

Done when: your router has a 10.0.0.x address on the WiFi interface and ping www.mikrotik.com answers.

Step 2 · Look at the country and the channel¶

Why: the country decides which channels your router may use. Check it is Spain.

WinBox: double-click the interface → Configuration (WiFi) or Wireless tab, Advanced Mode (legacy).

/interface wifi configuration print
/interface wifi radio print detail
/interface wifi radio reg-info 0 country=Spain

/interface wireless print detail where default-name=wlan1
/interface wireless info country-info spain

Expected: country=Spain (WiFi) or country=spain (legacy). radio print detail lists the bands and channels your hardware supports; reg-info (WiFi) and country-info (legacy) list the legal 2.4 GHz and 5 GHz channels and powers for Spain, including the ones marked for DFS.

Done when: you can say which country is set and name one DFS channel.

Step 3 · Set your radio name¶

Why: the teacher's AP sees twenty routers. In its registration table (the list of connected stations) it only sees MAC addresses like D4:CA:6D:E2:65:94. Which one is yours? The radio name solves that.

The radio name is a label your router sends to the AP, shown in the AP's registration table. It is a MikroTik extension: it only works between two RouterOS devices.

Use the course format YourNumber_YourName, for example 13_JohnDoe.

/interface wireless set [find default-name=wlan1] radio-name=13_JohnDoe

/system identity set name=13_JohnDoe
/interface wifi set [find default-name=wifi2] comment="uplink to ClassAP - 13_JohnDoe"

Ask the teacher to show the registration table (and IP → Neighbors) of class-ap on the projector, and find yourself.

Done when: the teacher can find 13_JohnDoe (your number and name) on the class router.

If something goes wrong¶

Clean up¶

Nothing to undo: the next lab starts from its own initial/ file. If you want to go back to this starting point, run the same reset with run-after-reset=r1.rsc (or r1-legacy-wireless.rsc) again.

Key takeaways¶

• WiFi is radio: a band (2.4, 5, 6 GHz) is divided into channels; higher bands are faster but reach less far through walls.
• In 2.4 GHz only channels 1, 6 and 11 do not overlap; 5 GHz has many more channels, some needing DFS radar detection.
• The country setting keeps your router legal: it limits channels and transmit power.
• An access point creates a network with an SSID; a station scans its scan list and joins it.
• RouterOS 7 has two WiFi menus: /interface wifi (wifi-qcom packages, WPA3) and the legacy /interface wireless used by the course slides.
• The radio name labels your router in a RouterOS AP's registration table; the new WiFi menu has none, so use the identity and IP → Neighbors.

Quick check¶

Your router now speaks WiFi as a client and has a name. In the next lab you will learn to tell it which access points it must not join.