[Sidrops] rfc8210bis further review - question 1

[Job Snijders <[e-mail]>]

Dear all,

I have some questions about rfc8210bis

Question #1
===========

In Section 8.2:

    Cache                         Router
      ~                             ~
      | -------- Notify ----------> |  (optional)
      |                             |
      | <----- Serial Query ------- | R requests data
      |                             |
      | ----- Cache Response -----> | C confirms request
      | ------- Payload PDU ------> | C sends zero or more
      | ------- Payload PDU ------> |   IPv4 Prefix, IPv6 Prefix,
      | ------- Payload PDU ------> |   ASPA. or Router Key PDUs
      | ------- End of Data ------> | C sends End of Data
      |                             |   and sends new serial

and section 5.6 "IPv4 Prefix" states

    """
    The cache server MUST ensure that it has told the router client to have one
    and only one IPvX PDU for a unique {Prefix, Len, Max-Len, ASN} at any one
    point in time.  Should the router client receive an IPvX PDU with a
    {Prefix, Len, Max-Len, ASN} identical to one it already has active, it
    SHOULD raise a Duplicate Announcement Received error.
    """

Imagine the cache emits the following sequence of PDUs:

   Cache                                   Router
   ~                                       ~
     <-- Serial Query                       
   Cache response                      -->
   Announce 2001:db8::/32 Origin 65535 -->
   Withdraw 2001:db8::/32 Origin 65535 -->
   Announce 2001:db8::/32 Origin 65535 -->
   End of Data w/ new serial           -->

A VRP for 2001:db8::/32 is announced, withdrawn, and announced again.

Should the above sequence of PDUs trigger the 'Duplicate Announcement
Received' error?

I'd take "only and only at any one point in time" where 'point in time'
is the window between the last serial and the next serial? To what
extend can routers expect caches to provide a consistent view within a
single Cache Response?

Kind regards,

Job