[Mip6] Comments on Binding Update Backhauling

Dear authors:

Your Internet Draft "Binding Update Backhauling"
<draft-haddad-mipv6-bub-00.txt> proposes a mechanism (BUB) to increase
the efficiency and security of location updates in MIPv6. In particular,
you seek to redundantize the Return Routability (RR) procedure during
all handoffs subsequent to the first (during which the "Do BUB" and "BUB
(N)ACK" messages are being exchanged).

On page 8, in the fourth paragraph of section 6, you state:

   If MN1 moves to a new network, it will send, in parallel, with
   the BU a CoTI message to MN2 using the new direct path between
   them (i.e., MN1 MUST perform a BCE lookup).

To our understanding, the RR test has two goals: (1) Ensure that the BU
has been sent by the *right* MN.  (2) Ensure reachability of the MN at
the new CoA.

We agree that BUB successfully provides issue (1) by authenticating the
BUs. However, since CoTIs and BU are sent in parallel, the BU obviously
does not contain any data that the CN sent along with its CoT. Hence,
the BU (in BUB) fails to ensure reachability of the MN at the new CoA,
i.e. issue (2).

Maybe we are we missing something?

If reachability assurance is not provided, a malicious MN may be able to
start a distributed DoS attack against a network, diverting large data
flows to the attacked network without actually being present there. By
the way, we noticed the same issue in your Internet Draft "Optimizing
Mobile IPv6 (OMIPv6)" <draft-dupont-ipsec-mipv6-04.txt>.

Sincerely,

- Tobias and Christian

PS: Here are links to the Internet Drafts mentioned above.

http://www.ietf.org/internet-drafts/draft-haddad-mipv6-bub-00.txt
http://www.ietf.org/internet-drafts/draft-haddad-mipv6-omipv6-00.txt

|
| Christian Vogt
| Institute of Telematics, University of Karlsruhe (TH)
| www.tm.uni-karlsruhe.de/~chvogt/
|

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