RE: manual config of UE tunnel [RE: 3gpp-analysis: Recommendation on tunneling in the UE]

[Pekka Savola <pekkas@netcore.fi>]

On Wed, 26 Nov 2003, Soliman Hesham wrote:
>  > > => This alternative is a non starter. This knowledge would not
>  > > exist unless static addresses are used, and they're not used
>  > > at all.
>  > 
>  > This cannot be true.  The home operator must know the address of the 
>  > UE, 
> 
> => Of course it knows it but it will know it in a different
> box (i.e. GGSN and DHCP for v4) but the tunnel end point
> is not on either one of those boxes.

Certainly.  But this is no problem.  You can get that information
using some means, e.g. SNMP.  I don't know which kind of interfaces
3GPP boxes have, and which kind management systems they connect to,
but I'm pretty sure there can be ways to extract that information.

>  > if for no other reason, but because it's tunneled back from the 
>  > foreign network.  
> 
> => I don't get this.

I mean, I understand foreign 3GPP operators use something like L2TP to 
transport the IPv4 packets back to the home operator, correct?  The 
home operator has to have some kind of policy to who will be allowed 
in its network, i.e., when decapsulating the L2TP stream from the 
foreign operator, the 3GPP operator should check the source addresses 
of the packets (or at least do something to check that the packets are 
valid, for billing etc. reasons if for nothing else).

>  > >  > minor modification to proto-41 decapsulation code at the 3GPP
>  > >  > operator's tunnel router, but basically that's it.  
>  > > 
>  > > => I'd rather not make this assumption either. 
>  > 
>  > Well, some rather might! :-)  Can you provide some technical 
>  > arguments?
> 
> => It doesn't exist today in routers AFAICS. 

Pretty close to trivial to implement.

> And there is no reason to introduce it when we can do with other
> mechanisms in products that people seem to prefer.

On the contrary, there is no reason to bless a solution (and impose
the burden of the solution on everyone eelse) that some have chosen
because they didn't think of alternative ways to achieve the result.

> => We can't assume that it is not well understood
> because one person made a mistake.

I can read myself, and I can say for sure that it isn't well 
understood. :-)

> It is implemented
> on 4 different products that I know of (2 host platforms
> and two router platforms) and are all interoperable. 

Implementatable & interoperable is VERY FAR from being well
understood.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings