RE: [Mip4] I-D ACTION:draft-ietf-mip4-dsmipv4-03.txt

["Sri Gundavelli" <sgundave at cisco.com>]

> -----Original Message-----
> From: Hesham Soliman [mailto:Hesham at elevatemobile.com] 
> Sent: Friday, August 10, 2007 5:44 AM
> To: 'Tsirtsis, George'; 'Sri Gundavelli'; 'McCann Peter-A001034'
> Cc: mip4 at ietf.org
> Subject: RE: [Mip4] I-D ACTION:draft-ietf-mip4-dsmipv4-03.txt 
> 
> 
>  > =========================================================
>  > Section 4.3.1.  IPv6 Packet Processing
>  > 
>  > Should be mentioned that Proxy ND is required only when 
> the requested
>  > IPv6 address is a HoA and not a IPv6 prefix.
>  > 
>  > GT> Hmmm, yes maybe. Is that simple statement sufficient 
> or should we
>  > say anything more?
> 
> => Basically we need to say that the HA will defed the IPv6 address by
> sending a proxy Neighbour Advertisement message. RFC 3775 talks about
> resending the message once for reliability. You could  refer to that
> behaviour. 
> 

I meant for the case, when the MN requests a prefix. HA need not
do any IPv6 ND operations. A simple route for the prefix over the
tunnel should be sufficient.


>  > Section 4.3.2
>  > 
>  > " Packets addressed to the mobile node's IPv6 link-local 
> address MUST
>  >     NOT be tunneled to the mobile node.  Instead, these 
>  > packets MUST be
>  >     discarded and the home agent SHOULD return an ICMPv6 
> Destination
>  >     Unreachable, Code 3, message to the packet's Source 
>  > Address (unless
>  >     this Source Address is a multicast address)."
>  > 
>  > The HA will probably never know the link-local address of the
>  > mobile node ? The document does not specify the operation of the
>  > mobile node using a IPv6 HoA on its home interface and also
>  > there is no "Link-Local Address Compatibility (L)" flag to tell the
>  > HA that the identifier for IPv6-HoA and the Link-local address is
>  > the same.
>  > 
>  > GT> Actually I am strangling to remember why or when we wrote this.
>  > Should I just remove it or is there something else we should say?
> 
> => I can't remember why we wrote this either. Looks like a 
> bug, but I'm
> wondering whether we should have the L-flag equivalent here 
> at all. It'd be
> interesting to see if anyone cares about link-local traffic, 
> e.g. DHCPv6,
> MLD...etc. 
>

The draft did not talk about of the use of IPv6 home address on the
home link. If the MN is on a virtual link or never at home, there
is no need for the HA to defend the mobile node's link-local address.
But, there is no such assumption mentioned in the spec. If the mobile
node operates as a normal MIPv6 node on the home link, we need to make
sure that address is defended by the HA, else it might loose it. MN
might use a link-local source address for DHCPv6 requests.

 
Sri


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