Re: RFC 3963: Clarifications if the MR is MN too

Jean-Michel COMBES wrote:

> Hi,
> 
> The RFC 3963 says in:
> 
> (1) Section 3, p5 "When the Mobile Router moves away from the home
> link and attaches to a new access router, it acquires a Care-of
> Address from the visited link.  The Mobile Router can at any time act
> either as a Mobile Host or as a Mobile Router. It acts as a Mobile
> Host as defined in [1] for sessions it originates and provides
> connectivity to the Mobile Network.  As soon as the Mobile Router
> acquires a Care-of Address, it immediately sends a Binding Update to
> its Home Agent as described in [1]. When the Home Agent receives this
> Binding Update, it creates a cache entry binding the Mobile Router's 
> Home Address to its Care-of Address at the current point of
> attachment."
> 
> (2) Section 4.1, p7 "A new flag (R) is included in the Binding Update
> to indicate to the Home Agent whether the Binding Update is coming
> from a Mobile Router and not from a mobile node.  The rest of the
> Binding Update format remains the same as defined in [1]."
> 
> (3) Section 4.1, p7 "Mobile Router Flag (R) The Mobile Router Flag is
> set to indicate to the Home Agent that the Binding Update is from a
> Mobile Router. If the flag is set to 0, the Home Agent assumes that
> the Mobile Router is behaving as a Mobile Node, and it MUST NOT 
> forward packets destined for the Mobile Network to the Mobile Router.
> 
> 
> Assuming that a MR is MN too, as described in (1), my questions are:
>  - (2) seems to indicate that such a MR has to send 2 BU: one with
> R=0 for MIPv6 and one with R=1 for MIPv6. Am I wrong?

In our implementation one R-BU is sufficient to "bind" both the HoA and
the complete MNP.  It was not in the intention to have two BUs sent one
for MH and one for MR.

> - (3) seems to indicate that a HA cannot manage NEMO and MIPv6. Am I
> wrong?

Terminology-wise, "If the flag is set to 0, the Home Agent assumes that
the Mobile Router is behaving as a Mobile Node" should probably better
say "Mobile Host" instead of "Mobile Node".  That would clarify things I
believe.

Implementations that I know of have a HA that either supports MH or both
MH/MR (a MN is an MH and MR actually, by the RFC3775 definitions I believe).

My oppinion,

Alex