Re: [mobile-ip] Re: FW: I-D ACTION:draft-tsirtsis-dsmip-problem-0 0.txt

George,

Tsirtsis George wrote:

>Fred,
>
>I am not sure what you are saying...a dual stack MIPv6 MN encountering a v4
>network will have no hope in sending a MIPv6 BU to its v6HA in any way that
>would allow real mobility.
>
>I guess one can imagine that such a mobile detecting a v4 only network could
>start going through the ngtrans tools and see what may work so that it can
>somehow get an IPv6 address and then tunnel a MIPv6 BU to its HA....as I
>said not real mobility.
>

Yes, this is the scenario I was referring to. First order of business is 
to get
some level of IPv6 connectivity in the visited network even if ip-proto-41
is required.

>Then I do not understand why you talk about this as if there needs to be
>"IPv6 over IPv6 over IPv4" tunneling involved. If the HoA is IPv6 and the
>CoA is IPv4 and MIP could be extended to create a binding between the two
>then an "IPv6 over IPv4" tunnel would be created.
>
The IPv6-in-IPv6-in-IPv4 part comes when 1) the HA needs to tunnel IPv6 
packets
to a MN in an IPv4-only visited network or 2) the MN in an IPv4-only network
needs to reverse-tunnel IPv6 packets through the HA to reach a CN. Not sure
how you mean about  MIP being extended to create a binding between IPv6
and IPv4. Do you see a way around the nested tunneling? (And, is there a
specification somewhere that tells how to do it?)

Thanks,

Fred
ftemplin=LXTkK8GSST62oZ/[email protected]

>
>George
>
>-----Original Message-----
>From: Fred Templin [mailto:ftemplin=LXTkK8GSST62oZ/[email protected]] 
>Sent: Wednesday, July 30, 2003 5:53 PM
>To: Tsirtsis George
>Cc: 'Alain Durand'; Mobile-Ip ([email protected]);
>[email protected]; Soliman Hesham; 'Thomas Narten'
>Subject: Re: [mobile-ip] Re: FW: I-D
>ACTION:draft-tsirtsis-dsmip-problem-00.txt
>
>
>George,
>
>Tsirtsis George wrote:
>
>  
>
>>Now, when the mobile is  not at home but in some other network, there 
>>is an issue about what kind of v4/v6 support there is in the foreign 
>>network. The nice thing about Mobile IP is that it is based on tunnels 
>>and thus it provides natural way of tunneling over networks that are 
>>not compatible with the mobile ...if only Mobile IP could configure v4 
>>over v6 and v6 over v4 tunnels (as opposed to just v4 over v4 and v6 
>>over v6 tunnels). A dual stack mobile in a v4 only foreign network 
>>would then be able to create a v4&v6 over v4 (forward and reverse) 
>>tunnel with its HA and thus maintain all its connectivity.
>>
>>    
>>
>When a dual-stack MIPv6 MN encounters a v4-only foregin network, I see (at
>least) three possibilities for the v6-in-v4 tunnel endpoint:
>
> 1) the tunnel endpoint resides in the home network; perhaps
>    even co-located with the HA (potential use case for configured
>    tunnels)
>
> 2) the tunnel endpoint resides in the visited netwok (potential
>    use-case for isatap)
>
> 3) the tunnel endpoint resides in some 3rd party network
>    (potential use-case for tunnel broker)
>
>In any case, the v6-in-v4 tunnel should present an MTU large enough to
>encapsulate 1280 bytes PLUS the size of the outermost IPv6 header so that
>the inner MIPv6  IPv6-in-IPv6 tunneling does not incur harmful fragmentation
>(see RFC 2473, section 7). But, most v6-in-v4 tunneling specifications cap
>their MTUs at 1280 bytes. Does this seem like a potential performance issue
>waiting to bite us?
>
>Fred
>ftemplin=LXTkK8GSST62oZ/[email protected]
>
>
>  
>