GUI wrong behavior with dhcp and /30 subnet

If I set a /30 for subnet and enable dhcp, starting pool address will be the same as interface adreess. Since dhcp pool don't accept same starting and ending address, dhcp can't be configure correcly on a /30 subnet.

Test on

Related to this feature request:

Hi Mike,

In Release DHCP settings follow common DHCP logic.

In /30 subnet only 2 IP addresses are available for distribution. DHCP section shows one of them as Starting and Second as Ending.

It is true that ePMP interface has assigned one of IP addresses from DHCP pool of /30 subnet, because of interface should be in the same subnet.

But other device in /30 subnet will receive proper IP address different from interface's IP address.

I would be really apreciate it if you could describe your view how it should work with /30 subnet.

Thank you.

@Fedor - I haven't tested the /30 dhcp behavior but I think the issue that Mike brings up is that if a /30 is assigned to the interface handing out DHCP there is only one address available to assign to a connected device. 

The way the GUI lists DHCP Start IP and DHCP End IP would imply that th eaddresses in that range including the start and end address can be assigned.  For a /30 it would be logical to have the start and end address be displayed as the same IP as that is the only one actually available for assignment.  This is how it would be displayed in most DHCP implementations.


I tend to agree with you, but in case of bigger subnet, for example /24 it is not possible te exclude Interface's IP address from DHCP pool on UI.

Please note Interface's IP address will be never assign to a connected device. 

The only thing which can improve usability in described case is to allow enter same IP address for DHCP Start IP and DHCP End IP.

Thank you.