Subject: [manet] New Version Notification for draft-lacharite-manet-holsr-01

From: Yannick Lacharité <[email-masked]>
Date: Tue, 18 Nov 2008 19:18:26 -0500

A new version of I-D, draft-lacharite-manet-holsr-01.txt has been  
successfuly submitted by Yannick Lacharite and posted to the IETF  
repository.

Filename:	 draft-lacharite-manet-holsr
Revision:	 01
Title:		 Hierarchical OLSR
Creation_date:	 2008-11-18
WG ID:		 Independent Submission
Number_of_pages: 34

Abstract:
This document describes the Hierarchical Optimized Link State Routing
(HOLSR) mechanism for heterogeneous mobile ad hoc networks.  In this
specification a heterogeneous mobile ad hoc network is defined as a
network of mobile nodes that are characterized by different
communication capabilities, such as communication channels,
processing powers or energy levels.

The HOLSR mechanism is an extension to the OLSRv2 protocol.  HOLSR
takes advantage of the node's distinct communications capabilities to
reduce the routing control overhead in large heterogeneous ad hoc
networks, thus improving the performance of the routing mechanism.
More precisely, HOLSR defines a hierarchy in the network and presents
a routing scheme for this hierarchical structure with a better
scalability.

The IETF Secretariat.

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From: Henning Rogge <[email-masked]>
Date: Wed, 19 Nov 2008 16:31:58 +0100

> Filename:	 draft-lacharite-manet-holsr

I have one question about the proposed HOLSR protocol, how do the cluster 
heads communicate with each other (on the same hierarchy) if they are outside 
direct communication range ?

Henning Rogge

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From: Yannick Lacharité <[email-masked]>
Date: Wed, 19 Nov 2008 11:35:18 -0500

See inline,

> direct communication range ?

If they are outside direct communication range, they will have to use  
their hierarchical levels to reach each other. Let's say they can't  
connect at level 1, they might be able to at level 2; if not they  
would have to go through level 3... There is a (I hope) good example  
of a communication stream in the Appendix A of the draft.

At a particular level, there are 2 cases that can be encountered about  
clusters:
1) They don't interconnect, in which case it is not physically  
possible to communicate at the same level.
2) They interconnect. Let's say cluster A interconnects with cluster  
B, in which case, MANET nodes from a cluster A close to the  
intersection area can communicate multi-hop directly with nodes from  
cluster B - without going through the cluster head. This special case  
is handled with the use of the C_INTER_DEPTH parameter as described in  
section 6.6.3 of the draft. It is to avoid having to go through  
cluster heads when shorter paths are available (for example, to avoid  
following a "10 hops path" when a "3 hops path" is available).

> Henning Rogge

-Yannick

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From: Henning Rogge <[email-masked]>
Date: Thu, 20 Nov 2008 09:30:02 +0100

Am Wednesday 19 November 2008 17:35:18 schrieb Yannick Lacharité:
> > heads communicate with each other (on the same hierarchy) if they are
> > outside direct communication range ?
>
I have read the example, but I'm still unsure if it works.

The example (page 9 of the draft) states that level 1 of the network are
all nodes, layer 2 contains the cluster heads of level 1 nodes and level 3 is 
a cluster of level 2 nodes.

I'm thinking about a scenario with lot's of 802.11 WLAN nodes. Some of them 
are mobile and have a single radio, some are fixed with a single radio and a 
few of them are fixed and have multiple radios and a higher range (maybe 
because of their phyiscal position).

Fixed nodes would be choosen as level 2 nodes, while multiradio nodes will be 
level 3 nodes, but there is no guarantee that all level 3 nodes will be able 
to hear each other (or that the layer 3 nodes create a continous mesh).

Theoretically layer 3 nodes could communicate through each other by using 
layer 2 (or even layer 1) connections, but I don't see an algorithm for this 
in HOLSR.

> following a "10 hops path" when a "3 hops path" is available).

My question is if the cluster heads are able to use this "lower parts" (not 
the higher parts) of the topology to get in contact with each other to from 
the higher topology meshes ?

Henning Rogge

---

From: Yannick Lacharité <[email-masked]>
Date: Thu, 20 Nov 2008 11:37:19 -0500

> layer 2 (or even layer 1) connections, but I don't see an algorithm for this
I think this can be answered in the following way: the highest layer  
of the architecture shall provide the overall connectivity of the  
network. If nodes at the highest layer (layer 3 from your example) are  
partitioned, then it might be better to not have a third layer. Thus,  
we would have an architecture where cluster heads at layer 1 are  
comprised of a mixture of fixed nodes, some with single-radio, and  
some with multi-radios. Such that these cluster heads appear as layer  
2 nodes. And that layer 2 would provide the overall continuous mesh...

> the higher topology meshes ?
Currently, the architecture does not support this. It might be  
interesting to study how that specific scenario could be supported and  
what changes to the specification it implies.

-Yannick