Subject: Re: [Roll] Energy metric for link

From: Alexandru Petrescu <[email-masked]>
Date: Tue, 28 Apr 2009 15:28:30 +0200

Mukul Goyal a écrit :
> Alex
> 
> There are many different aspects of energy consumption. Folks on this
>  list have already identified some of these aspects - battery levels,
>  the expectation regarding node life times, the power consumed for 
> transmission/reception on a link etc.

I am interested in a metric reflecting the energy needed for
transmission/reception on a link.  Unfortunately this type of metric is
only briefly alluded to by draft-mjkim-roll-routing-metrics-03:
   "Raw power and energy values are meaningless without knowledge of the
    energy cost of sending and receiving packets"

I agree with it and I propose to represent energy send/rcv in Watt
fractions in an RA, related to the MTU 1280bytes.

However, the draft takes a negative turn and says:
   "Given the complexity of trying to address such a broad collection of
    constraints, a much simpler path is preferable in the short term.  A
    few energy levels, for example, unlimited, scavenger supported,
    enough energy and low energy, may be sufficient to compute an
    adequate path in highly constrained scenarios will be specified in a
    further revision of this document."

And I don't agree at all with such conclusion.  I think it _is_ possible
to describe an energy representation and the relatic metric, for link
capabilities of sending/receiving 1280bytes.

> We may decide to define metrics representing each one of these 
> aspects. But the list seems endless to me.

Maybe we could converge defining a few (1, 2?) metrics and
representation... but we should start somewhere...

Alex

---

From: Mukul Goyal <[email-masked]>
Date: Tue, 28 Apr 2009 08:04:12 -0500 (CDT)

Alex

There are many different aspects of energy consumption. Folks on this list have already identified some of these aspects - battery levels, the expectation regarding node life times, the power consumed for transmission/reception on a link etc. We may decide to define metrics representing each one of these aspects. But the list seems endless to me. Some routing protocols, designed to optimize life times, may need this information from all/some nodes in the network while other protocols may consider such details strictly local. Whether such details are considered local or not may have an impact on the scalability of the protocol.

> I just think today although there are ideas about what a ROLL routing 
protocol may be, there is really no detail concept of an energy-related 
metric, or how that ROLL protocol may make use of it.

I agree.

Regards
Mukul

----- Original Message -----
From: "Alexandru Petrescu" <[email-masked]>
To: "Mukul Goyal" <[email-masked]>
Cc: "Richard Kelsey" <[email-masked]>, [email-masked], [email-masked]
Sent: Tuesday, April 28, 2009 6:59:18 AM GMT -06:00 US/Canada Central
Subject: Re: [Roll] Energy metric for link

Mukul Goyal a écrit :
> I am not sure if the routing protocol MUST aim for maximization of 
> the network life time.

I think the routing protocol could maximize for the network life time,
or for path life time, or for other relevant criterion.

I think it's worth conceiving the metrics now and make use of them in
various ways later.

> There will be a variety of the nodes in the network - some nodes
> dedicated to forwarding packets of others, some nodes just acting as
> end points and some nodes doing both operations. I think, rather than
> aiming for optimizing the life time/performance, the routing protocol
> should allow different "local" policies to be enforced. The routing
> protocol should not decide whether a node must participate in
> routing. The routing protocol should find the best routes among the
> nodes willing to forward packets. A node should be able to decide
> whether to forward packets or not based on the local policy factors
> such as battery levels.

I agree mainly with the policy aspect.

I just think today although there are ideas about what a ROLL routing 
protocol may be, there is really no detail concept of an energy-related 
metric, or how that ROLL protocol may make use of it.

Alex