RFC 8920, "OSPF Application-Specific Link Attributes", October 2020Source of RFC: lsr (rtg)
Errata ID: 6631
Publication Format(s) : TEXT
Reported By: Les Ginsberg
Date Reported: 2021-07-05
Section 5 says:
OLD If link attributes are advertised with zero-length Application Identifier Bit Masks for both standard applications and user-defined applications, then any standard application and/or any user-defined application is permitted to use that set of link attributes. If support for a new application is introduced on any node in a network in the presence of such advertisements, these advertisements are permitted to be used by the new application. If this is not what is intended, then existing advertisements MUST be readvertised with an explicit set of applications specified before a new application is introduced. An application-specific advertisement (Application Identifier Bit Mask with a matching Application Identifier Bit set) for an attribute MUST always be preferred over the advertisement of the same attribute with the zero-length Application Identifier Bit Masks for both standard applications and user-defined applications on the same link.
It should say:
NEW Link attributes MAY be advertised associated with zero-length Application Identifier Bit Masks for both standard applications and user-defined applications. Such link attribute advertisements MUST be used by standard applications and/or user defined applications when no link attribute advertisements with a non-zero-length Application Identifier Bit Mask and a matching Application Identifier Bit set are present for a given link. Otherwise, such link attribute advertisements MUST NOT be used.
RFC 8920 defines advertising link attributes with zero
length Standard Application Bit Mask (SABM) and zero length User
Defined ApplicationBit Mask (UDABM) as a means of advertising link
attributes that can be used by any application. However, the text uses
the word "permitted", suggesting that the use of such advertisements
is "optional". Such an interpretation could lead to interoperability
issues and is not what was intended.
The replacement text below makes explicit the specific conditions when
such advertisements MUST be used and the specific conditions under
which they MUST NOT be used.