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erikhrast
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DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 9:32 am

Hello... I own Mikrotik RB951G-2HnD (v. 6.35.4).

I noticed that every few minutes clients are deassigned and assigned IP address?
I search this issue on the forums but no solution worked for me...

There is about 50 address leases on the network and I never had this problem.
Mikrotik is configured as gateway and DHCP. All clients are wireless connected with UniFi AP.

DHCP debug log:

08:19:25 dhcp,debug,packet DHCP Kravanja received discover with id 1528368538 from

 0.0.0.0 
08:19:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
08:19:25 dhcp,debug,packet     chaddr = F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet     Msg-Type = discover 
08:19:25 dhcp,debug,packet     Client-Id = 01-F0-5B-7B-2F-78-F9 
08:19:25 dhcp,debug,packet     Max-DHCP-Message-Size = 1500 
08:19:25 dhcp,debug,packet     Class-Id = "dhcpcd-5.5.6" 
08:19:25 dhcp,debug,packet     Host-Name = "android-3ae9afaf1878d91d" 
08:19:25 dhcp,debug,packet     Parameter-List = Subnet-Mask,Static-Route,Router,Do
main-Server,Domain-Name,Broadcast-Address,Address-Time,Renewal-Time,Rebinding-Time
 
08:19:25 dhcp,info DHCP Kravanja deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet DHCP Kravanja sending offer with id 1528368538 to 192.1
68.20.57 
08:19:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
08:19:25 dhcp,debug,packet     yiaddr = 192.168.20.57 
08:19:25 dhcp,debug,packet     siaddr = 192.168.20.1 
08:19:25 dhcp,debug,packet     chaddr = F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet     Msg-Type = offer 
08:19:25 dhcp,debug,packet     Server-Id = 192.168.20.1 
08:19:25 dhcp,debug,packet     Address-Time = 72000 
08:19:25 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
08:19:25 dhcp,debug,packet     Router = 192.168.20.1 
08:19:25 dhcp,debug,packet     Domain-Server = 193.189.160.13,193.189.160.23 
08:19:25 dhcp,debug,packet DHCP Kravanja received request with id 1528368538 from 
0.0.0.0 
08:19:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
08:19:25 dhcp,debug,packet     chaddr = F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet     Msg-Type = request 
08:19:25 dhcp,debug,packet     Client-Id = 01-F0-5B-7B-2F-78-F9 
08:19:25 dhcp,debug,packet     Address-Request = 192.168.20.57 
08:19:25 dhcp,debug,packet     Server-Id = 192.168.20.1 
08:19:25 dhcp,debug,packet     Max-DHCP-Message-Size = 1500 
08:19:25 dhcp,debug,packet     Class-Id = "dhcpcd-5.5.6" 
08:19:25 dhcp,debug,packet     Host-Name = "android-3ae9afaf1878d91d" 
08:19:25 dhcp,debug,packet     Parameter-List = Subnet-Mask,Static-Route,Router,Do
main-Server,Domain-Name,Broadcast-Address,Address-Time,Renewal-Time,Rebinding-Time
 
08:19:25 dhcp,info DHCP Kravanja assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet DHCP Kravanja sending ack with id 1528368538 to 192.168.20.57 
08:19:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
08:19:25 dhcp,debug,packet     yiaddr = 192.168.20.57 
08:19:25 dhcp,debug,packet     siaddr = 192.168.20.1 
08:19:25 dhcp,debug,packet     chaddr = F0:5B:7B:2F:78:F9 
08:19:25 dhcp,debug,packet     Msg-Type = ack 
08:19:25 dhcp,debug,packet     Server-Id = 192.168.20.1 
08:19:25 dhcp,debug,packet     Address-Time = 72000 
08:19:25 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
08:19:25 dhcp,debug,packet     Router = 192.168.20.1 
08:19:25 dhcp,debug,packet     Domain-Server = 193.189.160.13,193.189.160.23 

Any ideas? Thank you...
 
pe1chl
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 10:36 am

I think this is related to clients that have lost their connection and then re-establish it.
I see it all the time in our network but I have never worried about it...
(this is a building with about 15 access points and people wandering around, sometimes outside the coverage)
 
erikhrast
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 10:54 am

I see... you think that this si nothing wrong with DHCP or AP...?
The thing is that I never noticed this before in MT logs - this is happening now for 2 weeks.

Users are staying in camping tents, so it is possible to lose signal. Maybe any extra AP for better coveragge?
 
jarda
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 11:20 am

Maybe. You should observe local situation and check the connection quality values. But anyway, more small cells with low t power are much better than one big.
 
erikhrast
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 11:36 am

Thank you for advice ;)
 
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ZeroByte
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jul 18, 2016 5:30 pm

Also - check that the lease time isn't something short like 10min.
Clients will renew their lease at 1/2 of the lease period.
When given a spoon,
you should not cling to your fork.
The soup will get cold.
 
erikhrast
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Re: DHCP deassigned, assigned every few minutes?!

Tue Jul 19, 2016 12:27 pm

Lease time is 20 hours.

It is very strange... just look at this logs. I don't think it is bad signal with clients...

05:35:19 dhcp,info DHCP deassigned 192.168.20.88 from 30:10:E4:81:7E:EF 

05:39:40 dhcp,info DHCP deassigned 192.168.20.101 from 4C:7C:5F:AE:C6:07 
06:36:42 dhcp,info DHCP deassigned 192.168.20.74 from D8:BB:2C:B0:2F:9C 
06:43:39 dhcp,info DHCP deassigned 192.168.20.91 from 5C:51:88:BC:B7:6A 
06:45:39 dhcp,info DHCP deassigned 192.168.20.111 from 68:A8:6D:71:BF:BE 
07:19:33 dhcp,info DHCP deassigned 192.168.20.87 from 8C:64:22:AE:BB:DD 
07:20:09 dhcp,info DHCP deassigned 192.168.20.90 from 54:2A:A2:7E:76:69 
07:20:09 dhcp,info DHCP assigned 192.168.20.90 to 54:2A:A2:7E:76:69 
07:28:35 dhcp,info DHCP deassigned 192.168.20.90 from 54:2A:A2:7E:76:69 
07:28:35 dhcp,info DHCP assigned 192.168.20.90 to 54:2A:A2:7E:76:69 
07:49:51 dhcp,info DHCP deassigned 192.168.20.90 from 54:2A:A2:7E:76:69 
07:49:51 dhcp,info DHCP assigned 192.168.20.90 to 54:2A:A2:7E:76:69 
07:51:58 dhcp,info DHCP deassigned 192.168.20.82 from A4:31:35:DA:E9:47 
08:13:41 system,info,account user admin logged in from 89.212.16.3 via winbox 
08:14:44 system,info,account user admin logged out from 89.212.16.3 via winbox 
08:25:15 dhcp,info DHCP deassigned 192.168.20.199 from 34:4D:F7:34:A8:0F 
08:25:15 dhcp,info DHCP assigned 192.168.20.199 to 34:4D:F7:34:A8:0F 
09:14:37 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
09:14:37 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
09:15:44 dhcp,info DHCP assigned 192.168.20.71 to 54:2A:A2:7E:76:8B 
09:30:36 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
09:51:38 dhcp,info DHCP assigned 192.168.20.138 to 34:BE:00:FF:68:5B 
10:13:33 dhcp,info DHCP deassigned 192.168.20.107 from D0:E1:40:BC:73:98 
10:13:34 dhcp,info DHCP assigned 192.168.20.107 to D0:E1:40:BC:73:98 
10:19:47 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
10:21:43 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
10:22:17 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
10:22:23 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
10:22:23 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
10:26:20 system,info,account user admin logged in from 89.212.16.3 via winbox 
10:27:08 system,info,account user admin logged out from 89.212.16.3 via winbox 
10:28:17 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
10:31:52 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
10:31:54 dhcp,info DHCP deassigned 192.168.20.57 from F0:5B:7B:2F:78:F9 
10:31:59 dhcp,info DHCP assigned 192.168.20.57 to F0:5B:7B:2F:78:F9 
10:56:21 dhcp,info DHCP deassigned 192.168.20.138 from 34:BE:00:FF:68:5B 
10:56:33 dhcp,info DHCP assigned 192.168.20.138 to 34:BE:00:FF:68:5B 
10:59:26 dhcp,info DHCP assigned 192.168.20.139 to E0:C7:67:AE:74:61 
11:01:41 dhcp,info DHCP deassigned 192.168.20.138 from 34:BE:00:FF:68:5B 
11:02:28 dhcp,info DHCP assigned 192.168.20.138 to 34:BE:00:FF:68:5B 
11:08:24 dhcp,info DHCP deassigned 192.168.20.113 from 78:C3:E9:2C:1A:08 
11:08:24 dhcp,info DHCP assigned 192.168.20.113 to 78:C3:E9:2C:1A:08 
 
pe1chl
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Re: DHCP deassigned, assigned every few minutes?!

Tue Jul 19, 2016 3:20 pm

I think nothing is wrong.  Only 192.168.20.57 (a Samsung device) is appearing a bit more often, but the others only occasionally.
When you can locate that user you could ask if they have a problem.  Probably not.
 
Zorro
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Re: DHCP deassigned, assigned every few minutes?!

Wed Jul 20, 2016 7:36 pm

maybe just signal propagation issues? eg clients - go beyond radios performance and back again.
or someone simply trying saturation/dos(not ddos;)attack ;)
consumers with worst radios performance - may had some special adjustments for or may not.
 
dsiecinski
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Re: DHCP deassigned, assigned every few minutes?!

Tue Jun 02, 2020 10:33 pm

I got newest firmware 6.46.6
DHCP set on 1h lease

This is not wifi connection problem
I got several cases with cable connection
...2-3 weeks with one ip problem
and then sudenly ...several weeks another ip

I suppose problem is only on Win10 but not sure
maybe this is something with Windows ?
 
mnfks2020
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Re: DHCP deassigned, assigned every few minutes?!

Tue Nov 03, 2020 4:24 pm

I have same issue, its not about signyal, maybe its have bug an rb9512hnd
 
tikmakro
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Re: DHCP deassigned, assigned every few minutes?!

Tue Nov 17, 2020 12:09 am

This is a major issue. Since the introduction of the DHCP script, many like me are using it to create DNS records (if search results are anything to go by). So this "dhcp,info my_net deassigned 10.0.0.15 from..." error deletes the associated DNS record and hence completely breaks connectivity to the affected hosts.

It happens regardless of the lease time. I increased from 10 minutes to 10 hours and still same deassigned problem occurs.

How can we diagnose the root cause? Is there some way to enable verbose logging?
 
pe1chl
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Re: DHCP deassigned, assigned every few minutes?!

Tue Nov 17, 2020 11:30 am

The root cause is that your device regularly loses connection to the network (e.g. due to bad WiFi) and then when it re-connects it also
releases and re-requests the lease. Not all devices do that, it depends on the firmware in the device and how it exactly reacts to connectivity
interruptions and how it handles lease extensions.
Some devices just try to renew the lease in this case and nothing is logged, others release and re-request it and you get those messages.
I even have a device that does this on every extension of the lease period even when the network is not interrupted.

W.r.t. the lease script: you program that yourself, when it does something you do not want, just change the script.
 
tikmakro
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Re: DHCP deassigned, assigned every few minutes?!

Tue Nov 17, 2020 11:31 pm

"bad WiFi" - My devices are wired, as are others' in this thread. But as a workaround, in my script, I've removed all lines that remove existing DNS records before creating new ones. This has kept the records in place since. Time will tell whether this introduces any new regressions. Thank you.
 
IV0nka
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Re: DHCP deassigned, assigned every few minutes?!

Mon Jan 11, 2021 9:59 am

@tikmakro
Could you please explain step by step how you solved this problem, because I have the same on my RB760iGS (fw 6.48)?

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