Re: [Mip6] [issue94] fixing encapsulation mechanism in IPv4 network

[Alexandru Petrescu <alexandru.petrescu at gmail.com>]

Keiichi SHIMA wrote:
> Hello Alex,
>
> On 2007/03/21, at 1:03, Alexandru Petrescu wrote:
>
> > I agree only one encapsulation mechanism (for traversing IPv4) is 
> > something useful, as opposed to implementing always two
> > encapsulating mechanisms.
> >
> > I'm not sure that UDP is the right answer for that.  IPv4-in-IPv4 
> > mechanisms (without UDP) have their advantages: less packet
> > overhead. They have inconvenients that they should be mainly in
> > kernelspace (constraints).
> >
> > Would it be possible to have DS-MIPv6 implementation with one big
> > MIB knob that says: -use UDP for BU signalling, traffic encap and
> > NAT traversal. or -use IPv4-in-IPv4 for BU signalling, traffic
> > encap and NAT traversal.
>
> It should work.  But what do you think about the idea to add a flag
> to specify the encapsulation mechanism in a binding update message as
>  proposed in my mail to Hesham?  With the proposal, we don't need any
>  manual configuration knobs and we can still use IPv*-in-IPv4
> mechanism, but allowing nodes that want to UDPv4 encapsulation only.

I think it could work (flag set by MN to specify UDP or IP encapsulation).

But should be done in tandem with that 'F' flag by HA.  One wouldnt want 
the MN to request eg UDP encapsulation and the HA to force IP encapsulation.

I prefer the MN to decide which encapsulation method to use (and not the 
HA).  However, the HA is the first to know whether there's a NAT in 
between.  A MN doesn't know whether there's a NAT in between, at the 
time it sends BU.

I've always thought there should be some form of tunnelling parameters 
negotiation between MN and HA, before sending the  BU/BAck.  Also 
periodic heartbeats with re-negotiation if necessary.

Alex


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