Re: New Version Notification for draft-petrescu-6man-ll-prefix-len-17.txt

Dear Alexandre,

I don’t believe this is in scope for 6man. 

Ole,
Your ever diligent co-chair. 

> On 10 May 2019, at 13:17, Alexandre Petrescu <alexandre.petrescu@gmail.com> wrote:
> 
> 
> 
>> Le 10/05/2019 à 12:38, tom petch a écrit :
>> ----- Original Message -----
>> From: <sthaug@nethelp.no>
>> Sent: Friday, May 10, 2019 9:30 AM
>>>>> Why OSPF(v3) for IPv6 does not use an IPv6 address in the neighbor
>> ID,
>>>>> and why does it use an IPv4 address instead?
>>>> both OSPFv2 and OSPFv3 use a 32-bit instance ID, which is
>>>> traditionally represented as an ipv4 address. It's not actually an
>>>> ipv4 address.
>>> 
>>> The 32bit instance ID responds to ping?
>> No.
>>> The 32bit instance ID is present in routing tables as next-hop?
>> No.
>> Think of it as a 32-bit *number*, not as an IPv4 address (because it
>> *is not* an IPv4 address).
> 
> In that case, the problem is in the textual representation of a 32bit value.  An uint32 cast into a struct in_addr and further converted by inet_ntoa to be displayed as a '1.1.1.1' instead of the intuitive '16843009' is misleading.
> 
> Probably the operating system of that router could be updated to no longer display the instance ID as an IP address.
> 
> In terms of spec, it seems Router ID of RFC2328 is the culprit, because RFC5340 says:
>> When receiving an Hello Packet from a neighbor on a broadcast,
>>        Point-to-MultiPoint or NBMA network, set the neighbor
>>        structure's Neighbor ID equal to the Router ID found in the
>>        packet's OSPF header.
> [...]
>>    Router ID
>>        A 32-bit number that uniquely identifies this router in the AS.
>>        One possible implementation strategy would be to use the
>>        smallest IP interface address belonging to the router.
> 
> RFC5340 OSPFv3 IPv6:
>> o  OSPF Router IDs, Area IDs, and LSA Link State IDs remain at the
>>      IPv4 size of 32 bits.  They can no longer be assigned as (IPv6)
>>      addresses.
> 
> It sounds as if it was possible to use IPv6 addresses as Router IDs before, but no longer.
> 
> Alex
> 
>> <tp>
>> Absolutely, it is a 32 bit identifier with no semantics at all.
>> Trouble is, an all too popular manufacturer decided that one way to
>> specify it was to make it an IPv4 address as well - both 32 bit, what
>> could go wrong? - sothere are many who now think that it is, even must
>> be, an address that can be reached over the network.  If you have some
>> of this kit, and an IPv4 network, then you may indeed be able to use
>> those 32 bits as a source IP address or a destination IP address but
>> that would be a case of a manufacturer deciding to go over and beyond
>> the specification and making future development more complex.
>> Thank heavens the OSPF WG carried the right concept across to OSPF v3.
>> Tom Petch
>> Steinar Haug, AS2116
>> --------------------------------------------------------------------
>> IETF IPv6 working group mailing list
>> ipv6@ietf.org
>> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
>> --------------------------------------------------------------------
> 
> --------------------------------------------------------------------
> IETF IPv6 working group mailing list
> ipv6@ietf.org
> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> --------------------------------------------------------------------