From: Yingzhen Qu <yingzhen.i...@gmail.com>
Sent: 30 December 2023 21:11

Hi Tom,

Sorry, but I don't understand your question. RFC8665 is for OSPFv2, and RFC8666 
is for OSPFv3. While in both cases, the TLV name is "Extended Prefix Range 
TLV", one is for OSPFv2 extended prefix LSA, the other may be advertised in:
E-Intra-Area-Prefix-LSA
E-Inter-Area-Prefix-LSA
E-AS-External-LSA
E-Type-7-LSA

I'm not sure whether this answers your question. More comments are welcome.

<tp>
No!

There are those in a world with only OSPFv2 routing domains with no awareness 
of the existence of OSPFv3; likewise there are those in a world with only 
OSPFv3 routind domains with no awareness of the existence of OSPFv2.  Then 
there are those who live with both, perhaps with boxes at the border of 
Enterprise and Operator.

And IETF documents exist in this world.  ospf-sr-yang models OSPFv2 and OSPFv3, 
it has RFC8665 and RFC8666 as Normative References and defines a leaf 'af' 
whose definition in RFC8666 contradicts that in RFC8665 unless and until 
RFC8666 is seen as updating RFC8665 and which could confuse those who 
comprehend the Normative References, IMHO.,  

Tom Petch

Thanks,
Yingzhen

On Sat, Dec 30, 2023 at 3:56 AM tom petch 
<ie...@btconnect.com<mailto:ie...@btconnect.com>> wrote:
Going through ospf-sr-yang-25 (and no, I do not want a new version for 
Christmas!) it seems to me that RFC8666 updates, RFC8665 even if the metadata 
does not mention it.

RFC8665 says
"      AF:  Address family for the prefix.  Currently, the only supported
         value is 0 for IPv4 unicast.  The inclusion of address family
         in this TLV allows for future extension.
"

while RFC8666 says
"      AF:  Address family for the prefix.
         AF:  0 - IPv4 unicast
         AF:  1 - IPv6 unicast
"
Since 8665 says 'only supported value' then this is  no longer valid and has a 
knock-on efffect when it comes to ospf-sr-yang.

If 8665 set up a registry (which I appreciate that the LSR WG has been 
resistant to doing in other cases) then adding a value to the registry would 
not be an update as per previous AD decisions but the phrase 'the only 
supported value is 0' can mislead until the reader understands 8666 (and may 
still do so).

Note that ospf-sr-yang has both RFC8665 and RFC8666 as Normative References so 
it is the implementor of the yang module that is at risk of misunderstanding.

I have a number of comments on ospf-sr-yang relating to this which I will post 
separately.

Tom Petch
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