Hi. /31 on ethernet links

[Chuck Swiger]

On Oct 30, 2009, at 5:22 PM, Sebastian Hyrwall wrote:
>> A /31 subnet is only defined for point-to-point network links, per:
>>
>>  http://www.rfc-editor.org/rfc/rfc3021.txt
>>
>> Ordinary ethernet links have BROADCAST flag set instead of  
>> POINTOPOINT.
>>
>
> Well how do I set the POINTOPOINT flag and remove the BROADCAST-flag  
> on ethernet links? Or are you implying that it does not belong on  
> ethernet links :)  Cause Cisco and Linux support /31 (ptp's) on  
> ordinary ethernet links.

Ethernet point-to-point links are normally handled by ppp / pppd in  
PPPoE mode, but possibly something like:

   ifconfig en0 inet 192.1.1.10 inet 192.1.1.2

...would give you a POINTOPOINT link instead.  If not, you can  
probably fake things out by either using a /30 and wrapping the /31  
inside, or using  a /32 and an explicit default route via your  
ethernet interface.

Regards,
-- 
-Chuck