Re: [Autoconf] aspects of multi-hop wireless communication

[Paul Lambert <[e-mail]>]

Hi,

It's great having a clear set of definitions to better describe our problem space.

It is good to be able to have a common understanding of asymmetric, non-transitive, and time-varying issues - however I feel strongly that all of these attributes should not be used to characterize all ad hoc networks.   Specifically - asymmetric networks are interesting, but they are an anomaly that is not present in most commercial link layer protocols.  At the link layer, radio networks are clearly asymmetric - but the data transfer services used to carry IP packets are acknowledged reliable link transmissions (aka bi-directional - not asymetric).

In this context it would be useful to be able to distinguish symmetric ad hoc networks versus non-symmetric ad hoc networks.  Can these be broken out as separate use cases in the definitions?

In this context I'd propose that you change in section 3 (and similar locations):

                We may say that router A has a link to router B. In this

      terminology, there is no guarantee that router B has a link to

      router A.
to

        We may say that router A has a link to router B. In this

      terminology, there is no guarantee in an asymmetric network that router B has a link to

      router A.

Other topics that I do not see fully defined are the:
- differences in link setup requirements and
- in the nature of a ad hoc networks support for multicast.

On link setup - it's often assumed that wireless communications once configured will allow communications between all peers without any explicit association or connection.  This has historically been a model of ad hoc communications (at least for 802.11).  Going forward (assuming IBSS is not displaced from Wi-Fi usage), this model must change to support link layer security.  Security is essentially connection oriented.  Every pairwise communication currently requires an explicit connection establishment (aka WPA 4-way handshake).  This connection is required for both unicast and any multicast communications (due to per device multicast key).  These means that for two devices on network to "hear" each other they had to first establish a explicit WPA  link layer 'connection'.

So Multicast then becomes a issue - not all ad hoc networks will have an ability  to support multicast.   This has considerable implications for the design of mechanisms for IP address assignment.

Regards,


Paul





________________________________
From: [e-mail] [mailto:[e-mail]] On Behalf Of Emmanuel Baccelli
Sent: Friday, December 19, 2008 1:19 AM
To: [e-mail]
Subject: [Autoconf] aspects of multi-hop wireless communication

Hi all,

here's a draft that aims at describing important aspects of multi-hop wireless communication, as observed over the past decade of experience with such networks.

The goal of this document is to identify a consensus about this topic, and then use this to move on quicker with the working group documents.

Please review it, and provide feedback as soon as possible.

http://tools.ietf.org/html/draft-baccelli-multi-hop-wireless-communication-00

cheers
Emmanuel

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