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Stril
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Mikrotik wifi roaming expirience

Fri Oct 09, 2020 9:39 am

Hi!

I am a long-time MT-user - administrating about 150 MT-devices, but I hope, you can give me some input, about roaming.

Wifi roaming should be mostly a client-process, but I am just not able to get a good roaming-expirience with mikrotik-wifi-devices.

Test-setup:
- 2 access-points
- perfect wifi coverage with overlap at -70dbm
- same positions for: Mikrotik hap ac2, Ubiquiti UAP-AC-Lite, Aruba IAP-515 (one after the next one)
- WPA2 personal, 17dbm
- dual radio
- no other wifi in range
- Test-Clients: Zebra 3200 (PDA - legacy 802.1a/g), iPhone 11 pro, Lenovo X1 carbon

--> Walking around with test devices between the APs and measure time of packet-loss by ICMP

Result:
Ubiquiti: Packet loss for 0.4-1s
Aruba: Packet loss for 0.6-1s
Mikrotik: Packet loss for 3-5s

Is there anything "tunable" to shorten this time? Config is quite basic: One bridge with both wifi interfaces.

Thank you for your help!
 
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Re: Mikrotik wifi roaming expirience

Fri Oct 09, 2020 10:06 am

Have you tried disabling lower datarates?
 
Stril
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Re: Mikrotik wifi roaming expirience

Fri Oct 09, 2020 10:23 am

Hi!

Yes, I tried this, but without success.
I already checked, if "forced disconnects" would help, but as I had enough overlap, clients did roam, before the "kick" would have happened.
 
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bpwl
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Re: Mikrotik wifi roaming expirience

Fri Oct 09, 2020 11:52 am

Kicking the client or making the wifi hostile to the client to force it to roam will never be better than letting the client roam on its own. (After the kick the process for roaming has still to start as a reaction to the kick, this adds some reaction time to the roaming process). 3-5 seconds is long!!! Knowing where, in what state the time is spend those 5 seconds is crucial.

This is my experience (production site) ..... client devices not under control.

By centralizing the "wireless log" one can see that the association to the new WLAN comes before the disassociation of the old WLAN if a device migrates from 2.4GHz to 5 GHz on the same AP.
Klembord-2.jpg
If hopping from AP to AP then the AP interconnection and the switch MAC tables must follow the topology change asap.
Klembord-3.jpg
Configuration is stand-alone AP's (no CAPsMAN), switch is RB260GSP.
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Re: Mikrotik wifi roaming expirience

Thu Oct 15, 2020 9:10 pm

-70 overlap seems a bit too hot to let something Want to Roam.
 
Stril
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Re: Mikrotik wifi roaming expirience

Fri Oct 16, 2020 12:58 pm

Hi!

I just found the main-issue:
viewtopic.php?f=7&t=167606&e=1&view=unread#unread

--> STP needs to be disabled
 
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Re: Mikrotik wifi roaming expirience

Fri Oct 16, 2020 5:24 pm

I use 78 for one AP and 75 for the other AP as cutoffs with a 10 second grace period)
So far things are smooth.
 
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Re: Mikrotik wifi roaming expirience

Sun Oct 18, 2020 1:53 pm

My reject rules is down near 87.
 
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Re: Mikrotik wifi roaming expirience

Sun Oct 18, 2020 5:40 pm

HI gotsprings, the problem with that (in my case ) is a user will then most likely stick with the AP on a very weak signal when a much better signal is available?????
 
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Re: Mikrotik wifi roaming expirience

Mon Oct 19, 2020 9:55 am

Try and throw them off too early... And they jump back on the same antenna.
 
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Re: Mikrotik wifi roaming expirience

Mon Oct 19, 2020 12:10 pm

Try and throw them off too early... And they jump back on the same antenna.
Yes they do. And this can happen very frequently.
Also handheld devices have regular dips in the signal strength because of hand and body obstruction. Therefore I set "Allow Signal out of range" to 30sec.
And then the units behind a wall or other obstacle... strong enough signal but very bad CCQ (<30%) , would like them to use another AP.
 
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Re: Mikrotik wifi roaming expirience

Mon Oct 19, 2020 8:50 pm

Thanks I will adjust timings to 30 seconds.
Thus my 0-75 out of range time is now 30 seconds --> If the signal drops to low, i dont want to kick off a device prematurely
SHOULD I, change my -76 to -120 delay time to 5 seconds LOL, or keep at 10. ----> Presumably if the signal is poor, the quicker I force the device to a better AP, the better????
 
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Re: Mikrotik wifi roaming expirience

Mon Oct 19, 2020 10:23 pm

Thanks I will adjust timings to 30 seconds.
Thus my 0-75 out of range time is now 30 seconds --> If the signal drops to low, i dont want to kick off a device prematurely
SHOULD I, change my -76 to -120 delay time to 5 seconds LOL, or keep at 10. ----> Presumably if the signal is poor, the quicker I force the device to a better AP, the better????
Well I don't know. My information comes from the wiki, and even the 'help' reincarnation of the wiki. But that leaves me clueless

It says the following:
For example, if client's signal during connection is -41 and we have ACL rule

/interface wireless access-list
add authentication=yes forwarding=yes interface=wlan2 signal-range=-55..0
Then connection is not matched to any ACL rule and if signal drops to -70..-80, client will not be disconnected.


To make it work correctly it is required that client is matched by any of ACL rules.

If we modify ACL rules in previous example to:

/interface wireless access-list
add interface=wlan2 signal-range=-55
add authentication=no forwarding=no interface=wlan2 signal-range=-120..-56
Then if signal drops to -56, client will be disconnected.
What? "Then connection is not matched to any ACL rule" , so -41 is not in the signal-range=-55..0 ? Is it not ?

and a second time, probably less accurate
signal-range (NUM..NUM - both NUM are numbers in the range -120..120; Default: -120..120)	

Rule matches if signal strength of the station is within the range.
If signal strength of the station will go out of the range that is specified in the rule, access point will disconnect that station.
The information about the " Allow Signal Out Of Range" is more cryptic , it is:
(void)
The full wiki-class information is missing: it would look like:
Allow Signal Out Of Range (time); default 0:00:10)          Time the signal is allowed out-of-range
Is the "Allow Signal Out Of Range" ever used in case of a denial (no authentication)? In what meaning? The fact that that rule is active even if the signal is strong ???? NO!
How to know? Experiments to confirm some hypothesis?


Mikrotik has no "concept manual", no "theory of operation manual", no "administrator guide", just a "command reference" even with parts missing.
no-LOL. We are wasting lots of time by misunderstanding the wiki.

(Try to find the information for mode "station-bridge" .....and "mode" information is not yet transferred to the 'help' reincarnation)
Klembord-2.jpg

EDIT: after checks not sure of the "NO!" anymore
Is the "Allow Signal Out Of Range" ever used in case of a denial (no authentication)? In what meaning? The fact that that rule is active even if the signal is strong ???? NO!
How to know? Experiments to confirm some hypothesis?
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Last edited by bpwl on Tue Oct 20, 2020 3:19 pm, edited 1 time in total.
 
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Re: Mikrotik wifi roaming expirience

Mon Oct 19, 2020 10:54 pm

Thanks, that was informative and entertaining............ We should make Normis recite that part of the WIKI 2000 times............
 
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Re: Mikrotik wifi roaming expirience

Tue Oct 20, 2020 12:05 am

There is more in this "access list" accept-reject process, than just these 2 cases.
But where is the "message manual" so we can understand the informative debug messages?

Accept/reject OK. But what is "banned (last failure - not allowed by access-list)". Comes after repeated rejects?
Or is this indeed the "Allow signal out of range" time for the reject rule ???????
(2 AP's for roaming hAP07w and wAP07. Elapsed time 3 sec)
Klembord-2.jpg
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Re: Mikrotik wifi roaming expirience

Wed Oct 21, 2020 1:12 am

Thanks I will adjust timings to 30 seconds.
Thus my 0-75 out of range time is now 30 seconds --> If the signal drops to low, i dont want to kick off a device prematurely
SHOULD I, change my -76 to -120 delay time to 5 seconds LOL, or keep at 10. ----> Presumably if the signal is poor, the quicker I force the device to a better AP, the better????
Well this might be an excellent idea. After 24 hours, with a much lower (3 sec) out of range time in the reject rule , I had no more "banned (last failure - not allowed by access-list)" messages !!!

So far the long out of range time in the reject rule seems to have triggered that banned condition.
Current setting: "Allow signal out of range " time for the authenticate rule (120..-86) is 30 sec, and 3 sec for the no-authenticate rule (-87..-120)

The test is only 24 hours young.
 
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Re: Mikrotik wifi roaming expirience

Wed Oct 21, 2020 1:43 pm

Thanks I will adjust timings to 30 seconds.
Thus my 0-75 out of range time is now 30 seconds --> If the signal drops to low, i dont want to kick off a device prematurely
SHOULD I, change my -76 to -120 delay time to 5 seconds LOL, or keep at 10. ----> Presumably if the signal is poor, the quicker I force the device to a better AP, the better????
Well this might be an excellent idea. After 24 hours, with a much lower (3 sec) out of range time in the reject rule , I had no more "banned (last failure - not allowed by access-list)" messages !!!

So far the long out of range time in the reject rule seems to have triggered that banned condition.
Current setting: "Allow signal out of range " time for the authenticate rule (120..-86) is 30 sec, and 3 sec for the no-authenticate rule (-87..-120)

The test is only 24 hours young.
If you don't enable "default authenticate" in the interface settings you do not need the NO-authentification rule!
Makes life easier for wifi admins and both rules will then not compete anymore or create race conditions ...
 
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Re: Mikrotik wifi roaming expirience

Wed Oct 21, 2020 2:13 pm


If you don't enable "default authenticate" in the interface settings you do not need the NO-authentification rule!
Makes life easier for wifi admins and both rules will then not compete anymore or create race conditions ...
Was also my deduction, in trying to understand the mechanism behind this.
This makes the "wiki" compleet "wacko" on this topic.
'Then connection is not matched to any ACL rule and if signal drops to -70..-80, client will not be disconnected.'
 
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Re: Mikrotik wifi roaming expirience

Thu Oct 22, 2020 5:12 pm

I know the Wiki for ACL is not very usable.

In general I see 10 db(?) (or what ever the signal strength is measured in) as the needed overlap between rules
for one device, to ensure it can always connect to one or the other device.
Shorter time outs than 30 secs are a problem as Wifi signal can quickly deteriorate or change as you said.
It also prevents ping pong effect between two AP or Wifi interfaces.
 
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Re: Mikrotik wifi roaming expirience

Wed Apr 26, 2023 11:08 am

Kicking the client or making the wifi hostile to the client to force it to roam will never be better than letting the client roam on its own. (After the kick the process for roaming has still to start as a reaction to the kick, this adds some reaction time to the roaming process). 3-5 seconds is long!!! Knowing where, in what state the time is spend those 5 seconds is crucial.

This is my experience (production site) ..... client devices not under control.....
Hello bpwl !
can you explain us how do you get a roaming time of less than 3-5 seconds? I've been trying various configurations for months and I can assure you that RouterOS has just those times and they can't compress them. Both L3 and L2. Even disabling RSTP/STP the times are still high just to reach again an L2 client that transmits data in broadcast.

Thanks
E.
 
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Re: Mikrotik wifi roaming expirience

Wed Apr 26, 2023 7:44 pm

How can I explain? All configurations are so different.

I would start with a simple test: how long does a new connection take, to start having traffic. And this is NOT when the client like Windows 10/11 indicates the wifi is connected. The connection is operational long before that. Windows does some testing (eg with DNS requests with random names, connect requests to some internet servers) that must pass before the wifi indicator changes to connected.

What is the real connection time for a new connection, or to a totally different wifi AP?

Roaming to the same SSID name, part of the same L2 network, should be compared to this; It should be faster. That is what is expected. (There is no DHCP lease request, firewall connections should still exist at the internet facing router... ) If it is slower, this is not expected and then we have to find the reason.

What can make the roaming slower than a new unrelated connection?

Just guessing, already discussed in this forum. But the initial test is the important part. If that is 2 to 3 sec already it must be investigated on it's own.

It's just not expected for the roaming to take longer... unless

- spanning tree transition of the L2 network. With STP enabled the disconnect of the last wifi client or the connect of the first wifi client to a wifi interface , makes the interface go down or start up. For STP this is a topology change, and will stop all traffic for the transition time.
- For R(STP) this is a topology change if the wireless interface is not an edge interface. ("AP-bridge" to "station-bridge" is not an edge situation for "auto")
- the old connection must probably disconnect first. There is a 3sec connection time-out, where the wifi AP will continue sending packets to a not responding wifi station
 
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Re: Mikrotik wifi roaming expirience

Thu Apr 27, 2023 12:36 pm

/interface wireless access-list
add signal-range=-85..120
add authentication=no forwarding=no signal-range=-120..-86
/interface wireless
set [ find ] default-authentication=no default-forwarding=no

# source: https://www.youtube.com/watch?v=1kWV7UahBok
Last edited by volkirik on Fri Apr 28, 2023 12:04 pm, edited 1 time in total.
 
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Re: Mikrotik wifi roaming expirience

Thu Apr 27, 2023 8:40 pm

Be ware with that youtube , and possible conclusions

- modified default setting : no-authenticate, no-forward, etc (like VLAN) are "interface default" settings. This means they will only be used if there is no matching "access list" rule.
- The shown access list entries cover almost all cases : -120 to -86 : with no authentication (and no forwarding)
- -85 till +120: authentication and forwarding. Note that there is a default 10 second "allow signal out of range" setting here, allowing the signal to drop for 10 seconds below -85, and still use this access list rule, and stay connected.
- only a signal between -86 till -85 could be a gap with no access list rule, and use the default

When the access rule with no-authentication is used, the client if connected is disconnected from the wireless network. What happens next, depends on the client. It probably will just try to reconnect, or start a scan for the best AP. Depends on the client logic.
If the client is disconnected multiple times from the same SSID (or maybe same BSSID= same SSID on same AP), the client might just create a bad wifi list, and will skip this BSSID (or much worse: skip this SSID) for the next connect attempt(s).
 
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Re: Mikrotik wifi roaming expirience

Fri Apr 28, 2023 12:04 pm

Hello bpwl !
what do you suggest? that is reasonable?
 
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Re: Mikrotik wifi roaming expirience

Fri Apr 28, 2023 12:30 pm

Well the rules above are not wrong. But they will not improve the roaming speed. They are intended to kick out slow connections (unfortunately only based on received signal strength at the AP), while hoping that the client reconnects to a better signal. That kicking sometimes has a negative side efect.""

We care mostly for the download speed. This is not the criterion for the kick-out. MT AP wifi has better numbers than received signal strength, like P throughput and CCQ.

For the roaming speed the reconnect is fast, but with MT the data flow takes 2 to 3 sec to resume (eg with a continous running PING test) when going to same or different SSID name on same L2 network. Better diagnostic tools are needed than just PING, to find out where the traffic is delayed, deviated or stopped for 2 sec.

in #4 above, the disconnect and reconnect seem to be at the same moment. But disconnect in a MT AP may be detected late. (There is the default 3 sec "disconnect timeout" ('advanced setting'), where the AP keeps resending packets ). Reducing that disconnect timeout, did not change much so far. There must be still something else.

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