RFC Errata
RFC 6822, "IS-IS Multi-Instance", December 2012
Note: This RFC has been obsoleted by RFC 8202
Source of RFC: isis (rtg)
Errata ID: 4521
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Alexander Okonnikov
Date Reported: 2015-11-02
Held for Document Update by: Alia Atlas
Date Held: 2015-11-11
Section 2.6.2 says:
In order for an MI-RTR to interoperate over a point-to-point circuit with a router that does NOT support this extension, the MI-RTR MUST NOT send IS-IS PDUs for instances other than IID #0 over the point-to-point circuit as these PDUs may affect the state of IID #0 in the neighbor.
It should say:
Note: The procedure below should not be used when MI-RTR is operating in point-to-point mode over broadcast circuit [RFC 5309]. In order for an MI-RTR to interoperate over a point-to-point circuit with a router that does NOT support this extension, the MI-RTR MUST NOT send IS-IS PDUs for instances other than IID #0 over the point-to-point circuit as these PDUs may affect the state of IID #0 in the neighbor.
Notes:
In Section 2.6.1, it clearly says "If operating in point-to-point mode on a broadcast circuit [RFC5309]" which reinforces that Section 2.6.2 is about point-to-point circuits and not broadcast circuits.
However, there isn't any harm in adding a bit of clarity going forward. This can be looked at if and when RFC 6822 is updated.