Subject: Re: [rrg] RRG Mobility Architecture

From: [email-masked]
Date: Fri, 7 Aug 2009 18:26:33 EDT

In einer eMail vom 30.07.2009 20:56:22 Westeuropäische Normalzeit schreibt  
[email-masked]:

The architecture v. engineering debate  is a red herring that gets thrown 
around too easily.  Every PhD student  has to do a literature survey to 
understand what has been done, in order to  demonstrate that there is at least 
something new to do that will improve  society.  That is what is needed here. 

100 % d'accord.

Nothing  more, and certainly nothing less, and it has been woefully lacking 
in the  past.  N.B., I am not asking that we get stuck in history– that is 
a  favorite pastime of this organization, but there is a balance between the 
two  extremes.

If we are going to create a new mobility architecture we  should understand 
how the existing ones work and don't work, and recognize  what is worthy of 
our time and what is not. 

Yes.Yes. Yes.My two cents: LISP is just to rescue an architecture which has 
 nothing in mind with respect to mobility. I do not blame the existing  
architecture because it is  older than the mobility objectives. But  what I do 
blame is  to ignore mobility objectives and to  rescue an architecture which 
is not at all appropriately designed.  
 
> We've all done the numbers.  What I stated were common  pitfalls the 
conversation usually follows like:

- trying to solve the problem  exclusively at L3, a favorite within the 
IETF.  You and I know that not  considering these problems from the transceiver 
to the application means poor  deployment (more on this later)

Yes,yes,yes. IMHO IEEE is completely ignored, i.e. the possibility to  
cooperate, instead  endless discussions are done about MTU-size problems  due to 
additional (LISP) headers. IMHO, the IETF and the IRTF think to hold all  
marbles in the own hands, but this is a wrong judgement. IEEE is in a much  
better position because it is handling the layer 2. And is competent and 
eager  to deal with Mobility. Of course, it would need layer 3 advertisements, 
but  there are well-known patterns how to do that (BGP does MPLS label 
propagation  for VPNs, why shouldn't it propagate Mobility-relevant information 
like  geographical coordinates and have the IEEE solve the problems which the 
IRTF  tries to solve for the last half decade)

. - not using the right tool for the right purpose.  I'll spare  the guilty 
parties, but you know who you are.

- simply not understanding what problem they are solving, and what  
problems to leave for others.  How many efforts (and perhaps entire  companies) 
have failed because of scope?  The IETF perhaps goes to the  other extreme now, 
but we'll leave that alone

- attempting to shoehorn every last problem into a solution.  I  believe in 
the need for locator/id separation, but it is not a  panacea. 

I believe in locators which have location significance i.e. by which you  
get a metric system, and not in location-agnostic RLOC identifiers as 
provided  by LISP.

For instance, use of different locators may have involve  different costs, 
that may need to be exposed all the way to the application  layer.  The 
iPhone demonstrates this best of all with some of its  apps.  And so the app 
can't simply cope with an identifier, as many would  like.  It has to have 
additional information (although it may not need  the locators themselves).

But back to that literature survey  thing.  People are often quite hard on 
MIPv6, and often for the wrong  reasons.  While MIPv6 bind times have often 
been viewed as atrocious,  often ranging from 20-60 seconds, in many 
instances that has been due to poor  signaling in the layers below.  The real 
problems with MIPv6 (putting  aside triangular routing in MIP) is the need for 
v6, firewall impedance  mismatch, and poor interaction of the layers above and 
below L3.  There  are assuredly other problems I'm not mentioning, like the 
complexity of  dealing with private address spaces.  HIP implementations 
have some of  these problems.  But that is often times it- we may in fact have 
the  right Internet standards but need work elsewhere.  And some  of this, 
such as FW traversal may be just poor incentive alignment, or scope  creep, 
depending on how you view the problem.  How do you view the  problem?

To restate my main point: if we're going to design a new  system, we had 
darn well better understand the old systems, and what their  limits are.
 
100 % d'accord.
 
BTW, what was the outcome of the rrg-meeting with respect to  mobility? 
IMHO it would be a big progress, if people acknowledged that - no matter  
what has been accomplished by MIBv4 /v6  so far - that  neither the  IPv4 nor 
IPv6-routing architecture are designed as to deal with these issues in  a 
natural way.
 
Heiner

Eliot

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