Subject: Re: alias netmask
To: Greywolf <greywolf@starwolf.com>
From: Sverre Froyen <sverre@viewmark.com>
List: current-users
Date: 04/09/2003 07:26:45
On Tuesday 08 April 2003 13:51, Greywolf wrote:
> Thus spake Caffeinate The World ("CTW> ") sometime Today...
>
> CTW> I use the same methods as you greywolf. However, according to the
> CTW> FreeBSD people, since alias 64.139.13.178/29, then the alias
> CTW> 64.139.13.181 following that should be /32.
> CTW>
> CTW> Which is the righ logic? or is there one
>
> I wasn't aware that /32 was considered "proper".  I'll go on record
> saying that my "logic" works for me, and it never occurred to me to
> do otherwise.
>
> At this point, I, too, would love other input!

It seems to me that the correct choice for netmask depends on the driver.  The 
netmask primarily defines how broadcasts (e.g., ARP requests) are handled.  
If the driver is able to receive and respond to an ARP request for the alias 
IP address on the "primary" address/interface, a /32 netmask might work.  
Similarly, if the driver sends ARP requests on all interfaces (primary and 
aliased), a /32 netmask would elimitate duplicate requests.

Sverre