On Sep 11, 2007, at 12:11 AM, Paolo Masci wrote:
Hi guys,
Thanks for the replies. I agree with you on the fact that
the routing tables are correct, i.e.
* the end-to-end link quality embeds the concept of distance
* routes have a cost that monotonically decreases
as the packet moves towards the base station.
Nevertheless, the implementation of RouteSelect.selectRoute(..)
still doesn't fully convince me: shouldn't we check that
the packet is actually decreasing the cost while it is
being forwarded? Both MintRoute and the old routing
algorithm (tos/lib/Route) included this check.
We know that routes have a cost that decreases when the
packet gets closer to the sink, but routes can change
while a packet is already being forwarded, and there
is no relation (I guess) between the cost of different
routes for different time instants.
For example, consider the following:
* suppose that node n0 sends a packet through
the path p0 = n1.n2...nx... with minimum cost
* suppose that there is a route update while the packet
is being forwarded, and that node nx decides to change
parent and selects a new route with minimum cost
px = ny.nz....
Although we know that px has a decreasing cost, we are
missing the relation with the previous path p0, and
the new path px may include some nodes of path p0, as well.
What do you think about this?
Yes, MultihopLQI can have transient loops. I think it hopes that its
duplicate detection will drop packets in them, and the parent
selection algorithm will finally figure things out. MLQI greatly
prefers links that have very high channel quality (and are therefore
reasonably stable).
Phil
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