Re: [OSPF] OSPFv2 operation on broadcast media with "slacked"/"discontinuous" IP addressing

    Hi David,
    problem of unnumbered IP on broadcast interfaces has little to do 
with OSPF. There are certain checks and assumptions built into IPv4 
architecture which prevent this (say, how ARP requests are accepted and 
validated; check concept of proxy ARP). So before you solve this problem 
in OSPF you should be messing with IPv4 basics and legacies of earlier 
days. At this point in time this is not interesting.
    As for /32 mask on broadcast interface see 
draft-ietf-ospf-prefix-hiding-04.

Anton


On 06/23/2012 11:00 PM, David Lamparter wrote:
> On Sat, Jun 23, 2012 at 01:17:40PM -0400, Acee Lindem wrote:
>> Nobody has ever suggested this - why do think it useful?
>
> Oops - context:  Unnumbered operation on broadcast media, and on that
> principle reduction of both IPv4 address consumption and configuration
> complexity.
>
> -David
>
>
>> On Jun 23, 2012, at 9:31 AM, David Lamparter wrote:
>>> out of a rather funny misunderstanding of RFC 5309, I've ended up with
>>> half an implementation of OSPF running in ignorance of the IP subnet
>>> mask on a broadcast network.  After cleaning up the misunderstanding and
>>> taking a step back, I found draft-ietf-ospf-hybrid-bcast-and-p2mp, which
>>> I expected to contain a note about this, but no such thing.
>>>
>>> The general idea would be to operate a broadcast medium with a /32
>>> subnet mask, possibly unnumbered, and allowing adjacencies with just
>>> about anything that sends a Hello (and passes auth).
>>>
>>> The link can operate as regular broadcast, hybrid-bcast-p2mp, or P-t-P
>>> (the last would amount to RFC 5309 with the detail that the peer address
>>> is not known up front.)
>>>
>>> (For OSPFv3, this is obviously not interesting since with link-local
>>> addresses, there is no notion of similar same-subnet restrictions.)
>>>
>>> I haven't found anything on this - is this mode of operation already
>>> described somewhere?
>
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