[Tinyos-devel] Multihop routing framework

[Romain Thouvenin]

Hello devel,

This follows a discussion begun on tinyos-help about having a
multihop routing framework on TinyOS 2.0, I hope I post on the right
place.

I am going to implement a multihop unicast routing protocol (DYMO) on
TinyOS 2. When I checked if there is a framework or guidelines for
that, I noticed there was such a framework in TinyOS 1.x, but not 2.0,
so I requested information on tinyos-help, where I got a reply from
Philip and Omprakash.

I just started to think about adapting the framework to TinyOS 2 and
my needs, while trying to keep something generic and partly reusable.
Here is a link showing the components and their interfaces :
http://www.daimi.au.dk/~romain/components-diagram.png

This is basically the same principle as in TinyOS 1.x : a top-level
component that abstracts the multihop routing. It is composed of three
main components. One handle the received message, one handle the send
commands, and the third one is the core routing components, which
updates and provides routes to the send component. This last one is
also made of three components. One implements the routing algorithms,
one implements the packet format, and the third one keeps the routing
table and manage neighbor discovery and monitoring.

I guess that integrating this in TinyOS would require to describe the
top-leve component, ForwardingEngine, MultiHopSend, RouteSelect and
RoutingTable. The first three ones are described in TinyOS 1
documentation.
Here is how I see RoutingTable :

interface RoutingTable {
   command void update(nghbr_info_t *);
   command nghbr_info_t * getRoute(addr_t);
   command uint8_t size();
   event void evicted(nghbr_info_t *, reason_t);
}

update adds or updates a routing entry, getRoute retrieves a routing
entry (especially nextHop) from an address. nghbr_info_t is an
abstraction like message_t, because routing protocols all require
differents fields in their route entries.


This is a first draft, you'll probably find various mistakes.
First, the control is not really specified, but I don't really know
how to do that. Do all the components provide a control ? Std or split
? Should a component handle the control of the whole multihop system ?
Next, I think I have misunterstood the use or principle of
RouteSelect. It is supposed to care about the format of the packet,
since the routeSelect command takes a message as a parameter and fills
the fields properly, but what prevents Multihop to use a different
format from RouteSelector ?


Here is where I am. What are your thoughts about that ? Is there anything good ?

Romain