RPL vs CORPL vs CARP-difference between RPL,CORPL,CARP IoT

This page compares RPL vs CORPL vs CARP used in IoT and mentions difference between RPL, CORPL and CARP. These are used as network layer routing protocols in IoT.

We are aware that network late is categorized into two sub-layers viz. routing and encapsulation. Routing layer takes of transferring packets from source to the destination while encapsulation layer takes care of formation of packets. All the three i.e. RPL, CORPL and CARP are network layer routing protocols.

RPL

Following are the features of RPL protocol as defined in RFC6550.
• It is distance vector protocol which supports various datalink protocols.
• Here DODAG (Dedicated Oriented Directed Acyclic Graph) has been built. This graph will have only one route from node to the root. From this single route all the traffic is routed.
• At the start, each of the nodes send DODAG information object (i.e. DIO). These messages are propagated in the network which help in construction of DODAG graph.
• When any node wants to communicate, it sends a DAO to its parents, DAO is propagated to root. Now root decides where to transmit it based on destination information available in the packet.
• Any node can join the network by sending the DODAG Information Solicitation (i.e. DIS) Request to join. Root replies back with DAO-ACK as sign of confirmation of the joining approval.
• Here all communications happen via root as it (i.e. root) has the complete knowledge of DODAG graph when stateless nodes are communicating. Stateful node has knowledge of its parents and childrens and hence communication inside sub-tree of DODAG does not require to go through root.

CORPL

Following are the features of CORPL protocol.
• It is extension of RPL protocol described above.
• It is designed for cognitive networks.
• It uses DODAG topology.
• It uses opportunistic forwarding in order to forward the packet between nodes.
• Here each node keeps information of forwarding set rather than only parent maintaining it. Each node update others using DIO messages. Based on which each node constructs forwarding set.

CARP

Following are the features of CARP protocol.
• CARP stands for Channel Aware Routing Protocol.
• It is developed for underwater communication and can also be used for IoT (Internet of Things) due to light weight packets.
• It selects the forwarding nodes based on link quality as per available historical data transmission from neighbours.
• There are two steps in CARP routing viz. network initialization and data forwarding.
• In network initialization, HELLO packet is being broadcasted from sink to all other nodes. In data forwarding, packet is being routed hop by hop from sensor to the sink. Here each of the next hop is determined independent of the others.
• E-CARP is enhancement to the CARP.

Following table mentions comparison between RPL, CORPL and CARP protocols.

Features	RPL	CORPL	CARP
Full Form	Routing Protocol for Low-Power and Lossy Networks	Cognitive RPL	Channel-Aware Routing Protocol
Server technologies	Supported	Supported	Not supported
Security	Not supported	Not supported	Not supported
Storage management	Supported	Not supported	Supported
Data management	Supported	Supported	Supported

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