On Fri, 19 Jun 2020 07:44:03 -0400 Daniel Ouellet <[email protected]> wrote:
> On 6/19/20 7:15 AM, Robert wrote: > > Hi, > > > > I want to configure multiple alias IPs on the same interface and in the > > same subnet. > > (reason: hosting services with dedicated DNS names and IPs) > > > > inet 10.0.0.1 255.255.255.0 > > inet alias 10.0.0.2 255.255.255.0 > > inet alias 10.0.0.3 255.255.255.255 > > ... > > > > What is the correct subnet mask for those alias IPs? > > If you have multiple IP's in the same subnet you enter then as /32 > > If you have two different subnet NOT in the same range, the first one of > the new subnet you enter it as it's full subnet and any additional one > in that second subnet you enter them as /32. > > Example: > > inet 10.0.0.1 255.255.255.0 > inet alias 10.0.0.2 255.255.255.255 > inet alias 10.0.0.3 255.255.255.255 > inet 10.1.0.1 255.255.255.0 > inet alias 10.1.0.2 255.255.255.255 > inet alias 10.1.0.3 255.255.255.255 > inet 10.2.0.1 255.255.255.0 > inet alias 10.2.0.2 255.255.255.255 > inet alias 10.2.0.3 255.255.255.255 > > It's always how I did it. If I am doing it wrong, then I never > understood it properly. May be the man page might benefit from > clarifying it. > > Hope this help you. > > Daniel > I have used both methods, and I have not seen any immediate issue. Which is why I am curious now if there are any technical or protocol reasons for one or the other. I am not worried about potential duplicate broadcasts in regard to bandwidth usage or similar. But are there any negative effects in the network stack or other states due to not using /32? /Robert
