17. RPL Constants and Variables

The following is a summary of RPL constants and variables:

BASE_RANK: : This is the Rank for a virtual root that might be used to coordinate multiple roots. BASE_RANK has a value of 0.

ROOT_RANK: : This is the Rank for a DODAG root. ROOT_RANK has a value of MinHopRankIncrease (as advertised by the DODAG root), such that DAGRank(ROOT_RANK) is 1.

INFINITE_RANK: : This is the constant maximum for the Rank. INFINITE_RANK has a value of 0xFFFF.

RPL_DEFAULT_INSTANCE: : This is the RPLInstanceID that is used by this protocol by a node without any overriding policy. RPL_DEFAULT_INSTANCE has a value of 0.

DEFAULT_PATH_CONTROL_SIZE: : This is the default value used to configure PCS in the DODAG Configuration option, which dictates the number of significant bits in the Path Control field of the Transit Information option. DEFAULT_PATH_CONTROL_SIZE has a value of 0. This configures the simplest case limiting the fan-out to 1 and limiting a node to send a DAO message to only one parent.

DEFAULT_DIO_INTERVAL_MIN: : This is the default value used to configure Imin for the DIO Trickle timer. DEFAULT_DIO_INTERVAL_MIN has a value of 3. This configuration results in Imin of 8 ms.

DEFAULT_DIO_INTERVAL_DOUBLINGS: : This is the default value used to configure Imax for the DIO Trickle timer. DEFAULT_DIO_INTERVAL_DOUBLINGS has a value of 20. This configuration results in a maximum interval of 2.3 hours.

DEFAULT_DIO_REDUNDANCY_CONSTANT: : This is the default value used to configure k for the DIO Trickle timer. DEFAULT_DIO_REDUNDANCY_CONSTANT has a value of 10. This configuration is a conservative value for Trickle suppression mechanism.

DEFAULT_MIN_HOP_RANK_INCREASE: : This is the default value of MinHopRankIncrease. DEFAULT_MIN_HOP_RANK_INCREASE has a value of 256. This configuration results in an 8-bit wide integer part of Rank.

DEFAULT_DAO_DELAY: : This is the default value for the DelayDAO Timer. DEFAULT_DAO_DELAY has a value of 1 second. See Section 9.5.

DIO Timer: : One instance per DODAG of which a node is a member. Expiry triggers DIO message transmission. A Trickle timer with variable interval in [0, DIOIntervalMin..2^DIOIntervalDoublings]. See Section 8.3.1.

DAG Version Increment Timer: : Up to one instance per DODAG of which the node is acting as DODAG root. May not be supported in all implementations. Expiry triggers increment of DODAGVersionNumber, causing a new series of updated DIO message to be sent. Interval should be chosen appropriate to propagation time of DODAG and as appropriate to application requirements (e.g., response time versus overhead).

DelayDAO Timer: : Up to one timer per DAO parent (the subset of DODAG parents chosen to receive destination advertisements) per DODAG. Expiry triggers sending of DAO message to the DAO parent. See Section 9.5.

RemoveTimer: : Up to one timer per DAO entry per neighbor (i.e., those neighbors that have given DAO messages to this node as a DODAG parent). Expiry may trigger No-Path advertisements or immediately deallocate the DAO entry if there are no DAO parents.