Subject: RE: [arch-d] Primary and lesser names, or layers of indirection?

From: John Day <[email-masked]>
Date: Thu, 23 Nov 2006 19:22:08 -0500

At 12:52 -0600 2006/11/23, Schliesser, Benson wrote:
>David Conrad [mailto:[email-masked]] wrote:
>>  Mobility is simply renumbering on a constrained time scale.
>>  Architecturally, support for multi-homing (in the sense of a network-
>>  attached-thingie having more than one name-thingie) is not required
>>  for mobility.  I would agree that multi-homing makes implementation
>>  easier.
>
>Though perhaps multi-homing can be treated as a sub-case of mobility, or
>vice versa? That is, multi-homing could be a case of mobility with
>multiple stable subnet connections, mobility could be a case of
>multi-homing with unstable/changing subnet connections. Conceivably we
>could have one solution for both views, no?

I have been meaning to say this to the list, but if you work through 
it carefully you will find that mobility should be nothing more than 
frequently changing multihoming.  But it isn't so much renumbering as 
the acquisition and release of points of attachment instances and 
node instances.

Take care,
John

_______________________________________________
Architecture-discuss mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/architecture-discuss

---

From: Geoff Huston <[email-masked]>
Date: Fri, 24 Nov 2006 11:52:25 +1100

>frequently changing multihoming.  But it isn't so much renumbering 
>as the acquisition and release of points of attachment instances and 
>node instances.

You appear to be re-covering some of the multi6 discussions with 
this. The critical distinction here is one that I've heard described 
as "nomadism" vs "mobility". Typically I've heard the term "mobility" 
to refer to a "home and away" model, where there is a fixed 
'reference point' for rendezvous, while "nomadism" has no such 
'home'. Multi6 highlighted this as there is no referential locator 
between the set of potential locators.  This appears to suggest that 
mobility (in the 'home and away' sense) is not a multi-homing case, 
and while you could view all mobility as nomadism, this appears to be 
a sub-optimal route in that the referential point has come in useful, 
particularly in respect to security functions associated with mobility.

regards,

   Geoff

---

From: John Day <[email-masked]>
Date: Thu, 23 Nov 2006 20:20:10 -0500

Yes, I believe the "home and away" model is probably more properly 
referred to as a "kludge."  The nomadic mode as you call it, if 
properly done actually has better security properties.  But then are 
so many ways to do it improperly.  ;-)  But it does seem to appeal to 
those partial to the phone company model of networking.

Take care,
John

At 11:52 +1100 2006/11/24, Geoff Huston wrote:
>>I have been meaning to say this to the list, but if you work 
>>through it carefully you will find that mobility should be nothing 
>>more than frequently changing multihoming.  But it isn't so much 
>>renumbering as the acquisition and release of points of attachment 
>>instances and node instances.
>
>as "nomadism" vs "mobility". Typically I've heard the term 
>"mobility" to refer to a "home and away" model, where there is a 
>fixed 'reference point' for rendezvous, while "nomadism" has no such 
>and while you could view all mobility as nomadism, this appears to 
>be a sub-optimal route in that the referential point has come in 
>useful, particularly in respect to security functions associated 
>with mobility.
>
>regards,
>
>   Geoff

---

From: Pekka Nikander <[email-masked]>
Date: Fri, 24 Nov 2006 09:06:35 +0200

Geoff,

> ... The critical distinction here is one that I've heard described  
> fixed 'reference point' for rendezvous, while "nomadism" has no  
> such 'home'.

I can easily understand that being stuck in the typical IETF  
discussions today, that becomes the case.

Unfortunately, when dealing with non-technical people, to them  
"mobility" means still something different.  To them "mobility" means  
that some physical, networked things either move around or are being  
moved around.  For example, that vehicles (embedded with nodes),  
humans (carrying nodes), etc, move around.  Even understanding the  
difference between subnetwork mobility and node mobility is hard for  
them.

Hence, when I am speaking about mobility I prefer to disregard the  
"home and away" model.  In my humble opinion, the "home and away"  
model was -- and still is -- a dire architectural mistake.  It was a  
hack that was designed to work for the then-current IPv4; rereading  
Charlie's et al 1996 IEEE Personal Communications paper may help.

The mistake the IETF took was to stick to the "home and away" model  
while moving to IPv6.  Today, even some ADs seem to agree that the  
orthodox or strict "home and away" model is causing more problems  
than solving.

> Multi6 highlighted this as there is no referential locator between  
> the set of potential locators.  This appears to suggest that  
> and while you could view all mobility as nomadism,

So far I agree, but ...

> this appears to be a sub-optimal route in that the referential  
> point has come in useful, particularly in respect to security  
> functions associated with mobility.

... with all respect, it is complete nonsense that the "referential  
point", i.e., the equivalent of Mobile IP home agent, would somehow  
be useful for security functions.  It is useful for rendezvous and  
tackling with the double jump problem.  However, you do not need to  
make the referential point as an architectural corner stone to  
achieve that.  You can relatively easily design combined mobility and  
multi-homing first, with full security and without any referential  
points, and then *add* the referential points to the design in order  
to ease rendezvous and double jump.  (That is what we did with HIP,  
as you should know.  And the same exercise would be easily done on  
the top of SHIM6/CGAs.  The latter exercise was alluded already  
before SHIM6 even existed, in the Roe & O'Shea 2001 CAM paper:
http://research.microsoft.com/research/pubs/view.aspx? 
type=Publication&id=1382 )

If you want a respected, peer reviewed publication, most of the  
security argumentation should be in 'Tuomas Aura, Pekka Nikander, and  
Gonzalo Camarillo, "Effects of Mobility and Multihoming on Transport- 
Protocol Security," in Proc. 2004 IEEE Symposium on Security and  
Privacy (SSP'04), Berkeley, CA USA, May 2004.'  I don't know if it  
gets it all, but at least we tried to get it there.

On the other hand, if with "useful... to security functions  
associated with mobility" you want to say that such a referential  
point is useful in securing certain business models, then I must agree.

--Pekka Nikander

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 24 Nov 2006 10:21:46 +0100

> On the other hand, if with "useful... to security functions  associated 
> with mobility" you want to say that such a referential  point is useful 
> in securing certain business models, then I must agree.

Why? That would imply that the reference point for AAA is in a layer 3
namespace. That doesn't seem right at all.

    Brian

---

From: Pekka Nikander <[email-masked]>
Date: Fri, 24 Nov 2006 14:21:07 +0200

Brian,

> namespace. That doesn't seem right at all.

What I was alluding to was my impression that most, if not all, of  
the security mechanisms build for Mobile IP seem to be based on the  
operator-centric idea where access and mobility security are combined  
or at least very compatible.  Of course, as such that does not  
directly favour any specific business models.

However, if the access provides take an administrative stance where  
they require that the security credentials used for access and those  
used for mobility management must be drawn from the same security  
infrastructure (say AAA), that may be turned to necessitate the  
mobile users to have a "home operator" in order to gain local access  
in the first place.  That, in turn, creates some sort of an  
oligopoly, through raising entry barriers.

In other words, the only thing I was alluding to is that the Mobile  
IP security work seems to be designed to favour (but not necessarily  
enforce) an operator-centric, oligopolistic business model.  Of  
course, that all is quite natural given who are defining those  
mechanism.  Requiring traffic, or at least some signalling traffic,  
to go through a "home network" is good for an operator-centric  
business model, and it is easy to build the involved security  
mechanisms so that they even more support such business models.

--Pekka Nikander

---

From: Scott W Brim <[email-masked]>
Date: Fri, 24 Nov 2006 08:43:23 -0500

On 11/24/2006 07:21 AM, Pekka Nikander allegedly wrote:
> In other words, the only thing I was alluding to is that the Mobile IP
> security work seems to be designed to favour (but not necessarily
> enforce) an operator-centric, oligopolistic business model.  

An "operator" can provide home addresses, tunneling,
authentication/authorization, charging and so on without actually
running more than a server farm and something that speaks routing.

---

From: Brian E Carpenter <[email-masked]>
Date: Fri, 24 Nov 2006 15:42:45 +0100

> running more than a server farm and something that speaks routing.

Not even that, if they are a fully virtual operator (like Tesco in
the UK is a virtual gas supplier).

But I think my point, and I think Pekka agrees, was that the nomadic
entity that needs to be authenticated is, e.g., "Scott W Brim", and not
some notionally fixed IP address. And a lot of practical nomadicity
works like that already, and is remarkably indifferent to IP addresses.

     Brian

---

From: "Bound, Jim" <[email-masked]>
Date: Fri, 24 Nov 2006 09:46:36 -0500

well stated Brian and this has to be part of the list of things to work
on per the mission.
/jim 

> -----Original Message-----
> From: Brian E Carpenter [mailto:[email-masked]] 
> Sent: Friday, November 24, 2006 9:43 AM
> To: Scott W Brim
> Cc: Pekka Nikander; [email-masked]; John Day
> Subject: Re: [arch-d] Nomadism vs. Mobility (was Re:Primary 
> and lesser names, or layers of indirection?)
> 
> Scott W Brim wrote:
> Not even that, if they are a fully virtual operator (like 
> Tesco in the UK is a virtual gas supplier).
> 
> But I think my point, and I think Pekka agrees, was that the 
> nomadic entity that needs to be authenticated is, e.g., 
> "Scott W Brim", and not some notionally fixed IP address. And 
> a lot of practical nomadicity works like that already, and is 
> remarkably indifferent to IP addresses.
> 
>      Brian
>