Subject: [MEXT] DSMIP draft 9

From: Christian Kaas-Petersen <[email-masked]>
Date: Thu, 26 Mar 2009 02:55:18 +0000 (GMT)

Reading draft 9, I did not find any text on the case of a
mobile node attaching to an IPv4-only home network, ie the
case where the mobile node has the address v4HoA, and
the home agent in its binding cache has the entry

    v6HoA -> v4HoA

Given this case is of particular interest to 3GPP,
I think it should be mentioned explicitly somewhere, for
example as one of the scenarios in Section 2.

Reading draft 9, I think some small details on NAT traversal
should be clarified.  Section 4.2.2 defines the NAT 
Detection option.  The option suggests a Refresh Time to
the mobile node.  

If Refresh Time = 0, then there was a NAT on the path,
but it is not clear if the mobile node is informed that
NAT refresh may be omitted, or if the mobile node shall
make an attempt to refresh the NAT binding using some
refresh time configured into the mobile node.  The
parameter NATKATIMEOUT is only for use in the home agent.

Another item on NAT, in four places (section 5.2, para 5;
section 5.4.3, para 3; section 5.4.3, para 5; section 5.5.1,
para 3) are stated, that the home agent may force UDP
encapsulation.  Also the mobile node may force UDP
encapsulation.

Related to this, section 5.4.2, bullet 6, ought to have
a "MUST" instead of "should".

Section 5.5.1, first packet, shall have UDP Header in
square brackets.

For the packets in section 6.2.1 and 6.2.2 I think it should
be stated, that V4ADDR can mean either the care-of address
or the address assigned by the NAT box.

Christian

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