On Apr 18, 2013, at 10:54, Carsten Bormann <[email protected]> wrote:
> Hope I can send around an update proposal today...
Here it is:
2.3.1. LLN ("low-power lossy network")
A related term that has been used recently is "low-power lossy
network" (LLN). In its terminology document, the ROLL working group
is saying [I-D.ietf-roll-terminology]:
LLN: Low power and Lossy networks (LLNs) are typically composed of
many embedded devices with limited power, memory, and processing
resources interconnected by a variety of links, such as IEEE
802.15.4 or Low Power WiFi. There is a wide scope of application
areas for LLNs, including industrial monitoring, building
automation (HVAC, lighting, access control, fire), connected home,
healthcare, environmental monitoring, urban sensor networks,
energy management, assets tracking and refrigeration.. [sic]
In common usage, LLN often stands for "the network characteristics
that RPL has been designed for". Beyond what is said in the ROLL
terminology document, LLNs do appear to have significant loss at the
physical layer, with significant variability of the delivery rate,
and some short-term unreliability, coupled with some medium term
stability that makes it worthwhile to construct medium-term stable
directed acyclic graphs for routing and do measurements on the edges
such as ETX [RFC6551]. Actual "low power" does not seem to be
required for an LLN [I-D.hui-vasseur-roll-rpl-deployment], and the
positions on scaling of LLNs appear to vary widely
[I-D.clausen-lln-rpl-experiences].
The ROLL terminology document states that LLNs typically are composed
of constrained nodes; this is also supported by the design of
operation modes such as RPL's "non-storing mode". So, in the
terminology of the present document, an LLN seems to be a constrained
node network with certain network characteristics, which include
constraints on the network as well.
I hope that is a bit more to the point, and helps correlate the ROLL
terminology to the one used in this document.
I'll look at your other points now.
Grüße, Carsten
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