Subject: [mobile-ip] Closing issue #269, destination's BCE not to be used for HOTI, COTI, BU

From: Jari Arkko <[email-masked]>
Date: Sat, 12 Apr 2003 17:05:14 +0300

I'm trying to close issue #269, which is about the use
(or not) of the binding cache when sending HOTI messages.
Previously, we have agreed that we need to (1) avoid sending RH with
HOTI, (2) send COTIs and BUs to home address of a CN which is itself
mobile.

Additionally, one of Erik Nordmark's comments in issue #289 was that
we should think about having a general rule for the use of HAO and RH2
with MH messages. Apparently, none of the MH messages are sent using a
BCE lookup, and only the only use of RH2 is for BA (even that without
a BCE lookup). HAO, on the other hand, appears only in BUs (and again
there not according to the existing binding).

What is the current situation in the draft?

  o  General: In draft 21 there are no general statements about HAO, RH2,
     and BCEs for MH messages.

  o  HOTI/COTI: In Section 11.6.1, we don't say anything special about the
     destination of the HOTI/COTI messages. Similarly, we don't say that
     RH2 should be avoided. Nor anything about HAO.

  o  HOT/COT: Section 9.4.3 specifies the destination of the HOT, and
     sort of implies that RH2 not be used. Section 9.4.4 specifies the
     destination of the COT message, but does not clearly state whether
     RH2 or HAO should or should not be used.

  o  BU: Section 11.7.2 does not say anything about the destination
     address of the BU or the use of RH2 towards it. HAO use is
     explained, however.

  o  BA: Section 9.5.4 specifies the destination address to use and
     explains the use of the RH2. The use of HAO is not explained.

  o  BE: Section 9.3.3 specifies how to set the destination. The
     use of HAO is not explained, nor is RH2. Those may be implied,
     however.

Proposal: Lets adopt Erik's suggestion and create a general rule on
how MH messages are sent. Here's the proposed text for section 6.1:

   Mobility Header messages MUST NOT be sent with a type 2 routing
   header, except as described in Section 9.5.4 for Binding
   Acknowledgement. Mobility Header messages also MUST NOT be used with
   a Home Address destination option, except as described in Section
   11.7.1 and Section 11.7.2 for Binding Update. Binding Cache
   information (when present) for the destination MUST NOT be used in sending Mobility
   Header messages. That is, Mobility Header messages bypass the
   Binding Cache check described in Section 9.3.2 which is normally
   performed for all packets.

Then we can remove the text related to RH2/HAO/BCE check from 9.3.3
and 9.4.3. Those sections would then say:

   A Binding Error message is sent directly to the address that
   appeared in the IPv6 Source Address field of the offending packet
   (before any modifications possibly performed as specified in Section
   9.3.1). If the Source Address field does not contain a unicast
   address, the Binding Error message MUST NOT be sent.

and

    The correspondent node creates a home keygen token and uses the
    current nonce index as the Home Nonce Index. It then creates a
    Home Test message (Section 6.1.5) and sends it to the mobile node
    at the latter's home address.

Note that these changes override some of the changes from issue
#274... should have waited a few hours with that mail ;-)

--Jari