Re: [Roll] [roll] #5: DODAG
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Roll] [roll] #5: DODAG
Hi Tim,
My question is: are there DAGs that are not DODAGs in RPL? My feeling is
no. Hence I would suppress the DODAG instead of turning all "DAG" into
"DODAG".
Best,
Julien
> -----Original Message-----
> From: roll-bounces at ietf.org [mailto:roll-bounces at ietf.org] On
> Behalf Of Tim Winter
> Sent: samedi 7 novembre 2009 19:55
> To: ROLL WG
> Subject: [Roll] [roll] #5: DODAG
>
> Hi Julien, WG,
>
>
> roll issue tracker wrote:
> > #5: DODAG
> >
> --------------------------------+-------------------------------------
> > --------------------------------+------
> > Reporter: jpv at ... | Owner: wintert at ...
> > Type: defect | Status: new
> > Priority: major | Milestone:
> > Component: rpl | Version:
> > Severity: Active WG Document | Keywords:
> >
> --------------------------------+-------------------------------------
> > --------------------------------+------
> > * This is currently being discussed by the RPL Author team *
> >
> > Email from Julien
> >
> > Is there a distinction between DAG and destination
> oriented DAG. From
> > what I read I feel all DAGs are destination oriented. If this is
> > correct I propose to remove the destination oriented DAG concept.
> >
>
>
> The intent for -05 will be to make the unqualifed use of
> `DAG' in the text consistent with `DODAG Iteration', as
> outlined below. So in this use, a `DAG' is a `DODAG'
> snapshotted by a single sequence number -- a `DODAG
> Iteration'. There may be cases in -04 where the text reads
> `DAG' and is in fact referring to `DODAG'- we will be sure to
> clean these up. Here below is some additional explanation
> prepared by the author team-
>
> Does this help to clarify?
>
> Regards,
>
> -Tim
>
>
>
> Instance
>
>
>
> +----------------------------------------------------------------+
> |
> |
> | (R1) (R2)
> (Rn) |
> | / \ /| \ / |
> \ |
> | / \ / | \ / |
> \ |
> | (A) (B) (M) | (N) ... (X) (Y)
> (Z) |
> | /|\ |\ / | |\ | |
> | |
> | : : : : : : (O) : : : :
> : |
> | / \
> |
> | : :
> |
> |
> |
> | Instance ID
> |
> |
> |
>
> +----------------------------------------------------------------+
>
> Instance
>
>
> An Instance is a routing topology over an LLN, optimized for a
> particular objective/application. Discrete Instances may
> also be set
> up to offer optimized connectivity to different destinations when
> appropriate, for example to differentiate a Home Network LLN from a
> Utility Network LLN in a smart metering application where
> a meter may
> be configured to join both Instances.
>
> It consists of one or more Destination Oriented DAGs (DODAGs).
>
> It is uniquely identified by an InstanceID.
>
> Each instance is operated independently of other instances, and RPL
> defines operation over only one instance. Operation among multiple
> instances is to be expanded upon in a future revision or companion
> specification.
>
>
>
> Destination Oriented DAG (DODAG)
>
>
> +----------------+
> | |
> | (R1) | (R2) (Rn)
> | / \ | /| \ / | \
> | / \ | / | \ / | \
> | (A) (B) | (M) | (N) ... (X) (Y) (Z)
> | /|\ |\ | / | |\ | | |
> | : : : : : | : (O) : : : : :
> | | / \
> | DAGID | : :
> | |
> +----------------+
>
> DODAG
>
>
> A Destination Oriented DAG is a DAG rooted at a single root node,
> which is a node with no outgoing edges.
>
> In the case where multiple nodes in the LLN coordinate over a
> backbone and expose the same DAGID (to support the same
> DODAG), it is
> conceptually as if there is a single virtual root over the backbone
> (not illustrated). In some applications/implementations
> this may be
> a desired architecture; in other applications each DODAG
> may operate
> with indpendent uncoordinated roots exposing different DAGIDs.
>
> A DODAG is uniquely identified over the LLN by the tuple
> (InstanceID,
> DAGID).
>
> In RPL a node may belong to only one DODAG per Instance at a time.
>
>
>
> DODAG Iteration
>
>
> +----------------+ +-----------------+
> | | | |
> | (R1) | | (R1) |
> | / \ | \ | / | \ |
> | / \ | ------\ | / | \ |
> | (A) (B) | \ | (A) (C) (B) |
> | /|\ |\ | / | /|\ |\ |
> | : : : : : | ------/ | : : : : : |
> | | / | |
> | Sequence N | | Sequence N+1 |
> | | | |
> +----------------+ +-----------------+
>
> DODAG Iteration
>
>
> A DODAG Iteration is the DODAG that results from the iterative
> process that reshapes the DODAG as stimulated by the root. It is a
> DAG as constrained by operation of RPL over a fixed
> Sequence Number.
>
> As the root node increments the Sequence Number, different types of
> node movement are allowed (e.g. moving `down') and a new DODAG
> Iteration is formed.
>
> A DODAG Iteration is uniquely identified over the LLN by the tuple
> (InstanceID, DAGID, SequenceNumber).
>
>
>
> Scope
>
> o The scope of an InstanceID is the whole network and it
> defines an
> instance
>
> o The scope of a DAGID is an instance and it defines a
> DODAG within
> that instance
>
> o The scope of a Sequence Number is a DODAG and it defines an
> iteration of that DODAG (DODAG Iteration)
>
> o The scope of a rank is a DODAG Iteration and it defines
> a position
> of a node within that iteration.
> _______________________________________________
> Roll mailing list
> Roll at ietf.org
> https://www.ietf.org/mailman/listinfo/roll
>
Note: Messages sent to this list are the opinions of the senders and do not imply endorsement by the IETF.
