Hi Acee, Rajesh,

RFC 6565 states that the same communities, defined in RFC 4577, are reused.

Just before the text, quoted by Rajesh, there is statement:

"The BGP Extended Communities attributes defined in [RFC4577] are reused for 
convenience."

RFC 4577 defines sub-type 0x05 and also refers to RFC 4360, where 0x00 and 0x01 
types are defined. Only gap, that I notice, is that RFC 4360 (and RFC 4577) 
mentions type 0x02, but doesn't define that type and doesn't point to reference 
of its definition (it was defined later in RFC 5668).

> 17 сент. 2021 г., в 17:15, Acee Lindem (acee) 
> <[email protected]> написал(а):
> 
> Hi Rajesh, 
>  
> This is the extended community type and RFC 6565 really should have had some 
> references for this - It took me a good 15-20 minutes to recall all the 
> details. The first octet specifies the extended community type of domain ID 
> as defined in https://www.rfc-editor.org/rfc/rfc7153.html#section-5.1.1 
> <https://www.rfc-editor.org/rfc/rfc7153.html#section-5.1.1>
>  
> TYPE VALUE       NAME
>  
>       0x00             Transitive Two-Octet AS-Specific Extended
>                        Community (Sub-Types are defined in the
>                        "Transitive Two-Octet AS-Specific Extended
>                        Community Sub-Types" registry)
>  
>       0x01             Transitive IPv4-Address-Specific Extended
>                        Community (Sub-Types are defined in the
>                        "Transitive IPv4-Address-Specific Extended
>                        Community Sub-Types" registry)
>  
>       0x02             Transitive Four-Octet AS-Specific Extended
>                        Community (Sub-Types are defined in the
>                        "Transitive Four-Octet AS-Specific Extended
>                        Community Sub-Types" registry)
>  
>  
> The second octet (0x05) is the registered sub-type value for the OSPF Domain 
> Identifier. See https://www.rfc-editor.org/rfc/rfc4577.html#page-10 
> <https://www.rfc-editor.org/rfc/rfc4577.html#page-10>.
>  
> Hope this helps,
> Acee
>  
> From: Lsr <[email protected] <mailto:[email protected]>> on behalf of 
> Rajesh M <[email protected] <mailto:[email protected]>>
> Date: Friday, September 17, 2021 at 5:44 AM
> To: "[email protected] <mailto:[email protected]>" <[email protected] <mailto:[email protected]>>
> Subject: [Lsr] Regarding OSPFv3 VPN Domain Type
>  
> Hi All,
>  
> For OSPFv3 from RFC 6565, section 4.4, it is mentioned that 2-byte type field 
> in the attribute.
> May I know what three different types 0x0005, 0x0105 0x0205 represent?
>  
>    OSPF Domain Identifier Extended Communities Attribute
>  
>    Each OSPFv3 Instance within a VRF MUST have a Domain ID.  The Domain
>    ID is configured per OSPFv3 Instance.  The OSPFv3 Domain ID is a
>    6-byte number, and its default value is 0.  This attribute has a
>    2-byte type field, encoded with a value of 0x0005, 0x0105, or 0x0205.
>  
>         0                   1                   2                   3
>         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>        |          Type Value           |    Domain Identifier          |
>        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>        |                     Domain Identifier Cont.                   |
>        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>  
>          The OSPF Domain Identifier Extended Communities Attribute
>  
> Thanks & Regards,
> Rajesh
>  
>  
>  
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