Subject: [mobile-ip] inconsistent description of the usage of BA code 137

From: "Bryan Xiangqian Wang" <[email-masked]>
Date: Wed, 30 Oct 2002 11:22:52 -0800

Hi,

There is an inconsistent description of the usage of BA code 137

While reading the following text in section 9.4.1

"   -  The Binding Authorization Data mobility option MUST be
       present, and its contents MUST be satisfy rules presented in
       Section 5.2.6."

One would naturally infer that BA 137 (Invalid or missing authenticator) MUST/SHOULD be sent to MN. But the following text rules it out. 

   "Packets carrying Binding Updates that fail to satisfy all of these
   tests for any reason other than insufficiency of the Sequence Number
   or Nonce Indices MUST be silently discarded."

Later we have the following text in section 9.4.4 that indicates we still have the chance to send  BA 137:

   "If the Status field in the Binding Acknowledgement contains the
   value 137 (invalid authenticator), 138 (expired home nonce index),
   139 (expired care-of nonce index), or 140 (expired nonces),
   then the message MUST NOT ..."

So if we do want to send BA 137, shall we make the following changes?

1.

   "Packets carrying Binding Updates that fail to satisfy all of these
   tests for any reason other than insufficiency of the Sequence Number
   or Nonce Indices MUST be silently discarded."

=>

   "Packets carrying Binding Updates that fail to satisfy all of these
   tests for any reason other than insufficiency of the Sequence Number
   or Nonce Indices, or missing or invalid authenticator MUST be silently discarded."

2. Consider adding some text into section 9.4.1, e.g. 

" If the Binding Authorization Data is not presented or invalid, then the receiving node MUST send back a Binding Acknowledgement with status code 137".

3. Remove the second "be" from the following text ;-)

"   -  The Binding Authorization Data mobility option MUST be
       present, and its contents MUST be satisfy rules presented in
       Section 5.2.6."

Thanks,
Bryan Wang
Elmic Systems, USA
(909)787-8475

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From: Jari Arkko <[email-masked]>
Date: Wed, 30 Oct 2002 21:58:08 +0200

Bryan,

Your issue sounds a real one, but fortunately we already removed
BA code 137 when issue #100 was being discussed. So no problem
any more ;-) but thanks for observing this anyway!

Jari