Subject: Re: clustering

From: Dennis Baker <[email-masked]>
Date: Wed, 01 Nov 2000 10:12:49 -0500

Dmitri,

At the Naval Research Laboratory (NRL), I have been working on what we now
call "Dynamic Backbone Subnets" (DBSs) since the early '80s. Our present
research
is focused on 802.11-based networks that self-organize into an 802.11
Extended Service Set (ESS). In this case, the clusterheads correspond to the
dynamically chosen Access Points (APs). We try to achieve a backbone in 
with the following properties: 1) Every STA is associated with an AP and 2)
the
backbone of APs is connected. As several others have pointed out, many
other factors need to be considered, such as battery power limitations and
(in our approach) how often STAs must change AP associations. Although,
our work with 802.11-based DBSs is still in the early stages, preliminary
results are very promising, and I would encourage you and others to look
further into the area of Dynamic Backbone Subnets.

Regards,
Dennis

At 03:55 PM 10/30/2000 -0500, Dmitri Deshun Perkins wrote:
>
>
>Hello,
>
>I have read some papers discussing the advantages offered by clustering and
>hierarchical routing in static or almost static environments Intuitively, 
>one would think some of these ideas may apply to MANETs especially 
>environments with a large number of nodes.
>
>However, I am curious to know how practical clustering would be in such a 
>dynamic(link failures, node movement, congestion, etc) network.
Specifically, 
>how would one select a clusterhead? Assuming all nodes have the ability to 
>move at anytime, the clusterhead could possibly move. Does the leader
election 
>algorithm elect the node that has been stationary the longest. What if this 
>node has the least power? It may not be a good choice? There would seem to
>be many other issues related to selecting(and reselecting) a clusterhead
in a 
>highly dynamic network such as a MANET.
>
>Your thoughts and feedback on the advantages/disadvantages surrounding
>these issues would be greatly appreciated. If this discussion has already
>taken place, please direct me to the-mail archives. Feel free to list any
>papers that compare hierarchical versus flat routing.
>
>Thanks for your time,
>D. Perkins
>