Subject: draft-chakrabarti-nordmark-6man-efficient-nd - Proposing new use case "Set-and-forget off-line network"

From: Anders Brandt <[email-masked]>
Date: Mon, 2 Sep 2013 09:44:10 +0000

[cross-posting 6man / 6lo]

Samita Chakrabarti et al,

Great draft which addresses important issues for low-power wireless network technologies.

After reading the draft, it seems to me that you would benefit adding one more use case -
and addressing the derived requirement(s).

Proposed use case:
-------
A.7.  Set-and-forget off-line networks
    Home control modules designed for networked environments may be deployed  
    in very simple settings like garden path lighting controlled by wireless  
    light and motion sensors. Once the network has been created and sensors  
    have been associated with the light modules, the installer takes away the  
    configuration tool which was used to set up the network. Most likely a ULA  
    prefix is used, since multiple hops may be needed. None of the sensors and  
    light modules has the capability of handing out fresh prefixes. Thus, for  
    a set-and-forget style off-line network to work, the nodes must be  able to
    operate forever without trying to refresh its address registration.

    In another instance of an off-line network, a key-fob style remote control is paired
    to a few lamp modules. The controller creates its own small off-line network.
    The controller is not only battery powered and sleeping. It is far away in its owner's pocket.
    Address registration is not possible.
 
     The manufacturer of the lamp module wants to sell exactly the same lamp
     module to large network deployments where address registration is used.
     Since this class of devices provide no local configuration interface, the behaviour needs
     to be controlled via some sort of auto-configuration.
-------
(end of proposed use case) 

One solution could be to introduce a special interpretation of registration lifetime 0xFFFF as infinite
and stating that default routers SHOULD NOT advertise this value.

Such an approach would resemble existing text in RFC4861:

 Valid Lifetime
                      32-bit unsigned integer.  The length of time in
                      seconds (relative to the time the packet is sent)
                      that the prefix is valid for the purpose of on-link
                      determination.  A value of all one bits
                      (0xffffffff) represents infinity.  The Valid
                      Lifetime is also used by [ADDRCONF].

The authors may have other preferred solutions?

Thank you,
  Anders