[ovs-discuss] DHCP IP addresses range of OVN's internal DHCP server

[Dominik Holler]

On Thu, 11 Jan 2018 18:31:25 +0530
Numan Siddique <nusiddiq at redhat.com> wrote:

> On Thu, Jan 11, 2018 at 5:31 PM, Dominik Holler <dholler at redhat.com>
> wrote:
> 
> > Hello,
> > what is the range of offered IP addresses by OVN's internal DHCP
> > server? 
> 
> Hi Dominik,
> Internal DHCP offers the IP address set in the logical_switch_port's
> addresses column. So, the CMS (cloud management system)  is expected
> to set it.
> 
> 
> > I am also interested in locating the source code which calculates
> > this range.
> >  
> 
> Alternatively, OVN supports basic IPAM implementation which actually
> assign's IP address to the logical switch ports from the configured
> range.
> 

Hi Numan,
this is the feature I am interested.

> All the documentation is available in "man ovn-nb" (grep for "IP
> Address Assignment"  and "DHCP") and "man ovn-northd".
> 

Even I use this man page quite often, I did not find the concrete range
in the man page.

> For IPAM you can find the code here -
> https://github.com/openvswitch/ovs/blob/master/ovn/northd/ovn-northd.c#L1114
> 

Thanks. Looks like IPAM returns for IPv4 the next smallest unused
address in the range of subnet address +1 (e.g. x.x.x.1) to biggest
subnet address-1 (e.g. x.x.x.254).

But from my experience the first port usually gets x.x.x.2.
Can you give me a hint why it does not get x.x.x.1?

> For DHCP here -
> https://github.com/openvswitch/ovs/blob/master/ovn/northd/ovn-northd.c#L2662
> 
> Thanks
> Numan
> 
> Thanks and regards
> > Dominik
> >