Wireless · Topic 4 of 4

Wireless Monitoring with the Snooper and the Registration Table

Use the RouterOS wireless snooper to study channel usage and the registration table to check connected clients, signal strength, rates and link quality.

  • 4 min
In a nutshell
  • The snooper shows channel usage, noise and the networks heard on each frequency.
  • Use the snooper to choose the quietest channel for an access point.
  • The snooper and scans can interrupt the interface, so avoid them on a busy access point.

What it is

Monitoring tools show what is happening in the radio environment and on each wireless connection.

The snooper looks at the channels around the router and reports who is using them. It helps you choose a channel with the least interference.

The registration table lists the clients connected to an access point, with the signal and rate of each link. It helps you judge the quality of a connection that already works.

Snooperscans channelsshowsChannel usagenetworks and loadguidesFrequency choiceless interferenceRegistration tableconnected clientsshowsLink qualitysignal and rate

How it works

One tool studies the air before you choose a channel, and the other studies each link after it is up.

The snooper

The snooper listens on the channels of the wireless interface and gathers statistics for each one.

/interface wireless snooper snoop wlan1

For each frequency it shows information such as:

  • the noise floor, which is the background radio noise
  • the percentage of time that the channel is in use
  • the number of networks heard on it
  • the traffic seen on the channel

A busy channel with many networks and a high noise floor is a poor choice. A quiet channel with low usage is a better one.

The snooper takes over the interface while it runs, so the normal wireless service on that interface may be interrupted. Run it during a quiet period, or on a spare interface, rather than on a busy access point.

Watch out

Running the snooper or a scan on a live access point can disconnect its clients, so plan it for a quiet time.

Using the snooper to choose a channel

The usual way to use it follows a few steps.

  1. Run the snooper on the access point interface, or on a station near it.
  2. Compare the channel usage and the noise floor of each frequency.
  3. Pick the quietest frequency that the country setting allows.
  4. Set that frequency on the access point.

Remember that interference comes from other networks and from non wireless sources too. The noise floor includes both of them.

The registration table

The registration table belongs to the interface, and it lists every client that is currently registered.

/interface wireless registration-table print
/interface wireless registration-table print detail

On an access point it lists the stations connected to it. On a station it lists the access point the station has joined. Each entry shows useful fields:

FieldMeaning
MAC addressThe address of the other end of the link
Signal strengthHow strongly the signal arrives, in dBm
TX and RX rateThe data rate in each direction
CCQA measure of the link quality, as a percentage
UptimeHow long the client has been connected

A signal closer to zero dBm is stronger. A good link shows a strong signal, a high rate in both directions and a high CCQ.

Weak or uneven values point to a problem. A strong signal with a low rate may mean interference. A weak signal on one side may mean poor antenna alignment or too much distance.

Reading the table

Use the table to answer common questions about a link:

  • Is the station connected at all? If it is not listed, it has not joined.
  • How good is the signal? Check the strength on both sides, and compare them.
  • Are both directions healthy? Compare the TX and RX rates.
  • How long has the link been stable? A short uptime suggests the link keeps dropping.

The table is also the first stop when you work with the access list. It shows the MAC address of a client that is currently joined.

Exam tip

Check the registration table first when a link seems slow, because it shows signal, rate and CCQ in one place.

What to remember for the exam

Six facts cover this topic.

  • The snooper shows channel usage, noise and the networks heard on each frequency.
  • Use the snooper to choose the quietest channel for an access point.
  • The snooper and scans can interrupt the interface, so avoid them on a busy access point.
  • The registration table lists the clients that are connected right now.
  • It shows signal strength, TX and RX rates, CCQ and uptime.
  • A signal closer to zero dBm is stronger.

Common mistakes

These four mistakes are common.

Running the snooper on a busy access point. Clients can be disconnected during the run.

Judging a link by signal alone. Also check the rates and the CCQ in both directions.

Choosing a channel by guesswork. Measure it with the snooper instead.

Reading only one side of the link. Check both the access point and the station, because the two ends can see different values.

Check yourself

Work through these three questions.

  • What does the snooper show?

    It shows usage statistics for each channel, such as the noise floor, how busy the channel is and which networks are heard. You use it to choose a quiet channel.

  • Which command lists the clients connected to an access point?

    /interface wireless registration-table print lists them. Each entry shows signal strength, TX and RX rates, CCQ and uptime.

  • Why should you be careful when running the snooper?

    It takes over the interface while it runs. Clients on a live access point can be disconnected.

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