[MEXT] Use of MR-HA tunnel for DHCPv6 signalling (in the context of DHCPv6PD for NEMO)

[Carlos Jesús Bernardos Cano <[e-mail]>]

Hi all,

	Reviewing draft-ietf-mext-nemo-pd, some people have commented that the
tunnel between the MR and the HA cannot be used for DHCPv6 signalling
between a DHCPv6 client @ the MR and a DHCPv6 server/relay @ the HA. The
point is that for messages sent to the MR from the HA, the HA is
operating as a CN and then it has to use RH2 to route the packet towards
the MR, instead of the MR-HA tunnel.

	My doubt is the following, Section 10.4.4 of RFC3775 (RFC3775bis does
not change this) says the following:

"10.4.4.  Stateful Address Autoconfiguration

   This section describes how home agents support the use of stateful
   address autoconfiguration mechanisms such as DHCPv6 [29] from the
   mobile nodes.  If this support is not provided, then the M and O bits
   must remain cleared on the Mobile Prefix Advertisement Messages.  Any
   mobile node which sends DHCPv6 messages to the home agent without
   this support will not receive a response.

   If DHCPv6 is used, packets are sent with link-local source addresses
   either to a link-scope multicast address or a link-local address.
   Mobile nodes desiring to locate a DHCPv6 service may reverse tunnel
   standard DHCPv6 packets to the home agent.  Since these link-scope
   packets cannot be forwarded onto the home network, it is necessary
   for the home agent to either implement a DHCPv6 relay agent or a
   DHCPv6 server function itself.  The arriving tunnel or IPsec SA of
   DHCPv6 link-scope messages from the mobile node must be noted so that
   DHCPv6 responses may be sent back to the appropriate mobile node.
   DHCPv6 messages sent to the mobile node with a link-local destination
   must be tunneled within the same tunnel header used for other packet
   flows."

Therefore, IMHO it seems that using DHCPv6PD signalling between the MR
and the HA would be perfectly possible, as stated in
draft-ietf-mext-nemo-pd-04. Am I missing something?

Thanks,

Carlos

-- 
Carlos Jesús Bernardos Cano     http://www.netcoms.net
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