[Unstrung-hackers] RPL requirements

Vijay Anand R vjanandrgky at gmail.com
Mon Oct 12 04:20:17 EDT 2015


Hi Michael,

I was trying to put together the set of things that is required from RPL 
for AN. Please add correct if any.


RPL requirements
================
The Routing Protocol for Low-Power and Lossy Networks (RPL) is a routing 
protocol for data plane datagrams in the IoT world. The routing protocol 
is particularly suitable for low powered devices and lossy links, hence 
the protocol is designed to produce its control plane traffic sparingly. 
The protocol is particularly suitable in scenarios where much of the 
traffic is P2MP or MP2P, and very little P2P and hence only a DODAG 
specific route is maintained and not that of a meshed network. This 
particular design methodology of RPL is suitable for control plane 
traffic of AN, as much of the communication is expected between the 
controller and the forwarding elements. The control plane traffic of AN 
is responsible for bootstrapping of devices multiple hops away from the 
controller/registrar. Please see above to understand how devices 
multiple hops away get bootstrapped.

Design Considerations
====================

a. The DODAG root is administratively configured to be the 
controller/registrar host.
b. The DIO message used to build the DODAG would be configured as below.
     i) The 128 bit DODAGID is the IPv6 Domain ULA address of the host 
device.
     ii) PIO option is not required to be distributed to the forwarding 
elements. The ULA address assignment is handled by AN control plane 
protocol.
     iii) The DODAG operates in Storing Mode of Operation with multicast 
support. P2P traffic is not required to be routed all the way to the 
DODAG root.
c. AN is more concerned with the connectivity of devices and hence not 
particular about a objective function. OF0 as defined in RF 6552 is 
suitable enough. Therefore the root and hence the DODAG is grounded.
d. The preference bit is the same for all nodes (could be 3).
e. The Domain ULA address is advertised in the DAO messages as 
reachability information.
f. The DAO messages are exchanged over the Overlay network over the 
IPSEC/GRE tunnels. Therefore the DODAG is constructed over overlay network.
g. Any new tunnel interface that is created by AN should be associated 
with RPL.
h. Election of a new ROOT when the current ROOT goes down could be based 
on the lowest prefixed IPV6 Domain ULA address. This is desirable so 
that the ULA address are assigned incrementally and the node closest to 
the current ROOT could potentially become the new ROOT. This is an 
implementation detail and is not covered in any of the RFCs.

Regards,
Vijay


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