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noneblah
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Neighbour discovery unexpected entry

Wed Feb 21, 2018 12:39 pm

Hey guys, :D

I have faced the following issue:

I have Mikrotik R1(pptp server) and Mikrotik R2(pptp client) - everything is working as expected, both of them are with public addresses, into the pptp they are using: 192.168.3.0/24. Address 3.1 for R1 and 3.2 for R2.

In to the /IP Neighbours, this is the output:

In R1:
2 ether2 x.x.x.x zz:zz:zz:zz:01:85 R2 6.41.2
4 ether3 zz:zz:zz:zz:01:8E R2 6.41.2


In R2:
2 ether2 y.y.y.y zz:zz:zz:zz:01:86 R1 6.41.2
4 ether3 fe80::.xyz.xyz.xyz.xyz zz:zz:zz:zz:01:87 R1 6.41.2


R1:
ether2 MAC address: zz:zz:zz:zz:01:86
ether3 MAC address: zz:zz:zz:zz:01:87


R2:
ether2 MAC address: zz:zz:zz:zz:01:85
ether3 MAC address: zz:zz:zz:zz:01:8E


R1 /ip address:

1 D 192.168.3.1/32 192.168.3.2 <pptp-R2>

2 D x.x.x.x/24 x.x.x.0 ether2

R2 /ip address:

0 D y.y.y.y/24 y.y.y.0 ether2

1 D 192.168.3.2/32 192.168.3.1 pptp-R1


My question is why R1 and R2 see each other through the neighbour discovery on ether3?
There is no bridge configured between ether2 and ether3, neither between the pptp interface or any of the ether ports.
If I disable ether3 on one of the devices, as expected there is no entry in the neighbour discovery table going through ether3.
 
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noneblah
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Re: Neighbour discovery unexpected entry

Wed Feb 21, 2018 1:20 pm

as addition on R1:

Just for the test I have added, firewall rule to log everything that goes into ether:

chain=input action=log in-interface=ether3 log=yes log-prefix=""

Time Feb/21/2018 13:11:55
Buffer memory
Topics
firewall
info
Message input: in:ether3 out:(unknown 0), src-mac zz:zz:zz:zz:01:8e, proto UDP, 0.0.0.0:5678->255.255.255.255:5678, len 117

which is exactly for the neighbour discovery, but still why ether3 is included, when there is nothing connected to it
 
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sebastia
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Re: Neighbour discovery unexpected entry

Sat Feb 24, 2018 2:03 pm

Which version of RouterOs are you using?
Maybe you still have a master-slave config on some of the ports...
 
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noneblah
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Re: Neighbour discovery unexpected entry

Tue Mar 06, 2018 12:48 pm

Hey, :)

The version of both routers is: RouterOS v6.41.2
Forgot to mention that both are: CHR, so I will double check whether there is any virtual switch from the hypervisor for these ports.

If anyone has other ideas?

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