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

["Hesham Soliman" <Hesham at elevatemobile.com>]

 > > switching between the UDP tunnel and IP n IP is very small (from an
 > > implementation point of view).
 > 
 > I may not agree on the above point.  Since UDP is a transport  
 > protocol, encapsulating something in it cannot be handled by a  
 > *normal* packet decapsulation flow, while IPv4-in-IPv4 can 
 > be fit to  
 > the natural flow.  So switching from IPv4 encapsulation to UDP  
 > encapsulation may not be so easy as you say, especially for MIP  
 > stacks that are implemented in user space.

=> I'm not sure I get that. If you're implementing in user space you would
still know how to handle IP n IP today because that's what MIP6 does today
and some people have already done that in user space. The UDP part is always
there because the BU is always sent on UDP. So if someone already implements
MIP6 in user space they already need to know how to handle IP n IP and if we
choose to do UDP only in DSMIP then they end up in a situation where they
have to handle both tunnelling mechanisms anyway. 

So to summarise for the user space case:

- You always need to handle IP n IP for native MIPv6 (it doesn't matter
whether it's v6 in v6 or v6 in v4, it's all IP n IP). 

- You always need to handle the UDP tunnel because the BU in DSMIP is always
sent in UDP. 

The difference in the DSMIP case is that normal traffic can also be
tunnelled in UDP, but that's the case you want to keep anyway. So you'll
always end up having to support both types of tunnels whether we remove IP n
IP from DSMIP or not. 

What am I missing? 

Hesham




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