DHCP Server is assigning the same IP in different interfaces

RouterOS General
1

Hello team!!

I have a Mikrotik router, which have 2 different subnets in 2 different interfaces
All is working fine
I just “Make static” a lease in 192.168.1.0/24 and after this, when I connect the same device in the other subnet, it still got the same IP, when I should get an IP in 192.168.10.0/24
Setting here:

/ip dhcp-server
add address-pool=pool_2 disabled=no interface="ether6" lease-time=1h name=dhcp-2
add address-pool=pool_1 disabled=no interface=bridge-FO.Garita lease-time=1h name=dhcp-1
/ip dhcp-server network
add address=192.168.1.0/24 comment="LAN 1" dns-server=192.168.1.1 gateway=192.168.1.1 netmask=24
add address=192.168.10.0/24 comment="LAN 2" dns-server=192.168.10.1 gateway=192.168.10.1 netmask=24
/ip dhcp-server lease
add address=192.168.1.146 client-id=1:c8:94:2:e:b:37 mac-address=C8:94:02:0E:0B:37 server=dhcp-1
/ip pool
add name=pool_2 ranges=192.168.10.128-192.168.10.254
add name=pool_1 ranges=192.168.1.128-192.168.1.190

Any idea?
Thanks in advance.
Regards!
Damián

2

Post all of the config. not just that bit.
Nobody can tell without.

3

And if you plug another device with a different mac into the same port, what address do you get? is it from 192.168.10.0/24?

Your problem description isn’t very specific, definitely not sufficient info for remote troubleshooting.

4

All the settings are more than 1200 lines, it will take too long time to modify enterprise name, site names, public IPs, Passwords and other confidential info, even using “replace all” feature in notepad
This MKT has VPNs with 6 different routers, and for both wans
Believe me, there are too much words to modify
If someone has a tip, this will be wellcome.

Regards,
Damián

5

This is not the original export, you have altered the lines. The proof is that ether6 is never in quotes.

add address-pool=pool_2 disabled=no interface="ether6" lease-time=1h name=dhcp-2

If a real censored export isn’t worth it for you, what do we care about your problem?

6

Thanks for your answer
If I plug another computer in the same port, it obtains a different IP
The isse seems like DHCP is giving reserved addressess for specified macs, even, when this mac is in another network

For example, suppose this:
We have 192.168.1.1/24 in ehter1
We have 192.168.10.1/24 in ether2
We have a DHCP Server in each interface and we connect a different switch in each port (I know I can use VLANs but there is not here so far)
We connect a device with mac 00:11:22:33:44:55 in the switch in ether 1, I get an IP in 192.168.1.0/24
We reserve the IP (Using “Make static” option), so this device will get allways the same IP address
We disconnect the device from the switch in ether1 and connect the same device in the switch in ether2
This device should get an IP in 192.168.10.0/24 but instead it get the same IP in 192.168.1.0/24
If we connect other device in the same port in the same switch, we get another IP in the correct segment.

Could I explain the issue clear enought?
Sorry, my english is not so good.

Regards,
Damián

7

If someone has the same issue before, maybe could give me a tip, if not, nevermind, forget the topic.

8

[unreliable-hypothesis]
Some devices ask the DHCP Server explicitly what IP they want, so that if, for example,
they disconnect and reconnect from the Wi-Fi they will resume the same IP, in order to reduce the hassle.
It may be that it is your own device that by still requesting the usual IP (reserved for it) is granted to it by the DHCP Server,
even if it is not part of the pool of THAT DHCP Server (but is a valid reserved IP for that MAC address).
[/unreliable-hypothesis]

9

Hmmm,
I will test what happen with another devices

Thanks.
Regards,
Damián

10

It would be good idea to mention RouterOS version. The behaviour is clearly not correct, so it might be bug, but it’s also not very likely that something like this would survive for too long without anyone noticing it. I tried quick test with 7.6 and nope, it doesn’t happen. As for testing it yourself, you don’t want other devices to connect to router, you want spare router with bare minimum config and try to reproduce it there.

11

@rbuserdl In general, when making a claim that something isn’t working as it is supposed to, and you think it is a bug, it is your responsibility to make a case for why you believe it is working incorrectly, with evidence.

What puts me off is that when asked a simple question

You responded with this answer:

Obviously we expect the dhcp server to offer a different ip to a different mac. But you avoided answering the question about what subnet the ip came from. There was a reason I asked, because if you got an address from the 192.168.1.0/24 then it is doing what is expected. Do you have a switch plugged into ether6 by any chance?

Did you capture the DHCP exchange with /tool/sniffer on the router or run wireshark on the PC getting the ip address?

What does ipconfig /all on the PC say about the the dhcp server?

Some useful guidelines when reporting “bugs” How to Report Bugs Effectively