Subject: About draft-vv-6man-nd-prefix-robustness-01

From: Paolo Volpato <[email-masked]>
Date: Tue, 30 Nov 2021 17:52:15 +0000

Dear WG,

During the past 6man session at the IETF 112, a question was raised whether "prefix robustness", as meant in draft-vv-6man-nd-prefix-robustness, is an issue and relevant precautions make sense.

In brief, ND or SLAAC do not request developers or administrators to be careful with PIOs invalidation.
Abrupt PIOs invalidation that may happen as a result of configuration change on switches or routers may be treated as a "configuration error" or "developer bug".
Deleting PIO in the configuration without deprecating it on the wire may be an example of that.
Sometimes it happens to people with IPv4 background where PIO deprecation was not needed. Cases are discussed in RFC 8978 with examples (including the example when people violate the 802.1x specification).

Hence, the question whether this is perceived as an issue and actions may be taken, as an example:

  *   "Don't forget to automatically deprecate stale prefixes on abrupt configuration changes or router shutdown",
  *   "Store previously delegated prefix in non-volatile memory to find the stale prefix after reload",
  *   "Clean associated prefixes too when default router expired and discarded",
  *   "Introduce new ND protocol flag for the router announcement that would inform the host that this information is comprehensive".

We would like to hear the opinion of the WG.
On behalf of the co-authors, many thanks
Paolo