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