Subject: RE: [manet] Suggestions for new problem statement

From: Joe Macker <[email-masked]>
Date: Tue, 03 Dec 2002 16:37:33 -0500

At 03:04 PM 12/3/2002 -0500, Scott Corson wrote:
>Richard,
>
>IMO this discussion is a rat hole for this group.
>
>The ANS (Ad hoc Network Scaling) research list is being established (should
>be available soon) for just this purpose and more.  It will be an open
>research subgroup.  The work there will objectively evaluate all the issues
>you raise and others, and will consider the performance of existing MANET
>proposals as well as possible variants/crazy ideas ;-) for comparison.
>
>I think there should be no notion of a *minimum* requirement for IETF MANET
>WG scaling.  We should not overly concern ourselves about this issue in the
>IETF.  Just build robust, stable protocols that work under a variety of
>common situations, while we ascertain the boundary/scaling/stability
>conditions where these protocols fall apart in the IRTF, to see
>when/where/how/why/if additional work is required.  Frankly, the wide range
>of possible traffic loadings and network dynamics can swamp all other
>considerations, rendering specification of a minimum size quite pointless.
>10 nodes or 250... either number can hold (or not), depending on a whole
>host of assumptions.

Scott I tend to agree.  Heavily quantifying minimum size or means little without spelling out a whole host of other metrics and scenario specific related issues (which defines a RATHOLE argument space for generality).... Mea culpa for throwing such numbers up in the strawman.  Speed is also not a generic metric for mobility because it doesn't take into account the variables relating to the scale of relative motion across a wide range of scenarios.  Also, in my opinion MANET technology is not just about handling potential relative motion but also about simple wireless link dynamics and time varying interface behavior.

To reiterate the proposal in Atlanta, we should focus in on simple, practical approaches in the IETF MANET realm that work for a variety of more commonly envisioned scenarios (and I believe we have some good engineering lessons learned finally on the table to build of off..) The ANS will serve to debate the larger scale analysis, performance tweaks, and design choices.  Within the IETF scope, after our initial EXPERIMENTAL targets, I would be more interested in achieving the goal of simple operational robustness and flexibility for basic cases at the engineering level.  Some may say we have that already, but what we don't have is consensus on a common WG engineered approach.  In addition, if we can design a degree of extensibility into any adopted core framework(s) we are in reasonable good shape for the future enhancements that will certainly come along.

Let's hear from more of you on this...

>I don't believe we should even list 100 nodes as a requirement... I think
>network scale should be a non-goal in the IETF work.  Common sense
>engineering should be able to produce reasonably efficient protocols without
>needless overspecification.
>
>-Scott
>
>
>> I would like to offer some suggestions for the new problem 
>> statement.  
>> Joe presented a preliminary problem statement that said the protocol 
>> should support up to 100 nodes, but I know this is up for discussion.
>> 
>> At the meeting in Atlanta, at least one person suggested 
>> that we not limit ourselves to only 100 nodes since some or all
>> of the proposed protocols can already support more than that,
>> and I agree with this.  
>> 
>> I know that AODV, TBRPF, and OLSR can all support at least 250 nodes
>> and probably more, using 802.11 with rate 2 Mbps.
>> 
>> I think the protocol should be as scalable and efficient as 
>> possible without being "too complex", and without using
>> hierarchical routing.  
>> 
>> It is generally agreed that the protocol should be extendable
>> to a scalable protocol (e.g., using a hierarchical method such
>> as landmark routing).
>> HOWEVER, IF THE PROTOCOL CAN SUPPORT MORE NODES WITHOUT USING
>> HIERARCHICAL ROUTING, THEN ITS HIERARCHICAL EXTENSION WILL
>> SUPPORT MORE NODES.  (The same is true for other scalability
>> techniques such as HSLS and FSR.)
>> 
>> Perhaps the problem statement can give 100 or 250 nodes as a 
>> *minimum requirement*, and state that when alternative techniques are 
>> available that are reasonably simple and well understood, preference 
>> should be given to techniques that perform better, e.g. that:
>> 
>>   1. Support more nodes 
>>   2. Support a higher level of mobility and dynamics
>>   3. Have better delivery ratio and end-to-end delay
>>   4. Provide shorter paths
>>   5. Generate less overhead (or "total overhead")
>>   6. Support lower bandwidth links 
>> 
>> We also need to be careful about stating the minimum requirements for
>> mobility.  For example, the number of topology changes per second for 
>> nodes traveling 20 mps according to the random waypoint model is much 
>> greater in an urban environment than it is in an open field.
>> 
>> Richard 
>> 
>> _______________________________________________
>> manet mailing list
>> [email-masked]
>> https://www1.ietf.org/mailman/listinfo/manet
>> 
>_______________________________________________
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---

From: "Tao Lin" <[email-masked]>
Date: Tue, 3 Dec 2002 18:55:23 -0500

We developed a framework for the MANET routing protocols.  The draft of this
paper is available at http://io.irean.vt.edu/~tlin/.

"A framework for mobile ad hoc routing protocols" T. Lin, S. F. Midkiff, and
J. S. Park, accepted by IEEE WCNC 2003.

This framework can characterize the MANET routing protocols, including
DSR/AODV/TBRPF/OLSR and other drafts proposed in the IETF MANET web site.
This framework points out the multi-objective optimization problems (or
trade off problems) in the design/improvement of these protocols.
Therefore, I hope it can be helpful for the future study of MANET routing
protocols.

 Best,

      Tao Lin
  ECE Department
  Virginia Tech.
  USA

----- Original Message -----
From: "Joe Macker" <[email-masked]>
To: <[email-masked]>
Sent: Tuesday, December 03, 2002 4:37 PM
Subject: RE: [manet] Suggestions for new problem statement

> Scott I tend to agree.  Heavily quantifying minimum size or means little
without spelling out a whole host of other metrics and scenario specific
related issues (which defines a RATHOLE argument space for generality)....
Mea culpa for throwing such numbers up in the strawman.  Speed is also not a
generic metric for mobility because it doesn't take into account the
variables relating to the scale of relative motion across a wide range of
scenarios.  Also, in my opinion MANET technology is not just about handling
potential relative motion but also about simple wireless link dynamics and
time varying interface behavior.
>
> To reiterate the proposal in Atlanta, we should focus in on simple,
practical approaches in the IETF MANET realm that work for a variety of more
commonly envisioned scenarios (and I believe we have some good engineering
lessons learned finally on the table to build of off..) The ANS will serve
to debate the larger scale analysis, performance tweaks, and design choices.
Within the IETF scope, after our initial EXPERIMENTAL targets, I would be
more interested in achieving the goal of simple operational robustness and
flexibility for basic cases at the engineering level.  Some may say we have
that already, but what we don't have is consensus on a common WG engineered
approach.  In addition, if we can design a degree of extensibility into any
adopted core framework(s) we are in reasonable good shape for the future
enhancements that will certainly come along.

---

From: "Tao Lin" <[email-masked]>
Date: Tue, 3 Dec 2002 18:55:23 -0500

Best,

      Tao Lin
  ECE Department
  Virginia Tech.
  USA