Network Transport Layer

standardised

easy accessible for applications

standardised, widly used

constrained devices, constrained networks

payload, no fragemntation with IPv6

21 bytes

Low Power Wireless Personal Area Network

Wireless access technology for low-cost and low-data-rate devices powered on

batteries.

for low power devices

Home and building automation

− Automotive networks

− Industrial wireless sensor networks

− Interactive toys and remote controls

1. IPv6 header compression

2. IPv6 packet segmentation and reassembly

3. Layer 2 forwarding (mesh under)

bigger payload

reusing fields from lower levels to get to know needed information into the higher levesl

IPv6 only

UDP

Fragmentation of IPv6 packets across multiple layer 2 frames

The Datagram Size is 11-bit field that encodes the size of the entire IP packet before link-layer fragmentation. The

value of Datagram Size shall be the same for all link-layer fragments of an IP packet. For IPv6, this shall be 40 bytes

(the size of the uncompressed IPv6 header) more than the value of Payload Length in the IPv6 header of the

packet.

This field does not need to be in every packet, as one could send it with the first fragment and elide it

subsequently. However, including it in every link fragment eases the task of reassembly in the event that a second

(or subsequent) link fragment arrives before the first. In this case, the guarantee of learning the Datagram Size as

soon as any of the fragments arrives tells the receiver how much buffer space to set aside as it waits for the rest of

the fragments. The format above trades o simplicity for efficiency.

The value of the Datagram Tag shall be the same for all link fragments of a payload datagram. The sender shall

increment the Datagram Tag for successive, fragmented datagrams. This field is 16 bits long, and its initial value is

not defined.

The Datagram Offset field is present only in the second and subsequent link fragments and shall specify the offset,

in increments of 8 bytes, of the fragment from the beginning of the payload datagram. This field is 8 bits long. The

first octet of the datagram (e.g., the start of the IPv6 header) has an offset of zero; the implicit value of Datagram

Offset in the first link fragment is zero.

The Datagram Size is 11-bit field that encodes the size of the entire IP packet before link-layer fragmentation. The

value of Datagram Size shall be the same for all link-layer fragments of an IP packet. For IPv6, this shall be 40 bytes

(the size of the uncompressed IPv6 header) more than the value of Payload Length in the IPv6 header of the

packet.

This field does not need to be in every packet, as one could send it with the first fragment and elide it

subsequently. However, including it in every link fragment eases the task of reassembly in the event that a second

(or subsequent) link fragment arrives before the first. In this case, the guarantee of learning the Datagram Size as

soon as any of the fragments arrives tells the receiver how much buffer space to set aside as it waits for the rest of

the fragments. The format above trades o simplicity for efficiency.

The value of the Datagram Tag shall be the same for all link fragments of a payload datagram. The sender shall

increment the Datagram Tag for successive, fragmented datagrams. This field is 16 bits long, and its initial value is

not defined.

The Datagram Offset field is present only in the second and subsequent link fragments and shall specify the offset,

in increments of 8 bytes, of the fragment from the beginning of the payload datagram. This field is 8 bits long. The

first octet of the datagram (e.g., the start of the IPv6 header) has an offset of zero; the implicit value of Datagram

Offset in the first link fragment is zero.

IPv6

forwarding packets over multiple IP hops

Link-layer mesh is possible with some wireless technologies that include multihop forwarding features such as the recently completed IEEE 802.15.5 standard [IEEE802.15.5]. The original 6LoWPAN specification [RFC4944] includes an option for carrying mesh source and destination addresses, which can be used by a forwarding algorithm. No standard algorithms for use with this mesh header have been defined, and therefore the realization of LoWPAN mesh has been implementation specific. Currently, the most common technique instead employs IP routing.

Routers and interconnects are constrained, and many routers

• routers and interconnects are constrained,

• high loss rate, low data rate

• few dozen to thousand of routers

RPL is based on Directed Acyclic Graph (DAG) concept

mesh-over routing because routing is performed at the IP layer

outing protocol for wireless networks with low power consumption and generally susceptible to packet loss,optimized for multi-hop and many-to-one communication, but also supports one-to-one messages

To cope with the constraints of computing and memory that are common characteristics of constrained nodes

Storing mode: All nodes contain the full routing table of the RPL domain. Every node knows how to directly reach

every other node.

Non-storing mode: Only the border router(s) of the RPL domain contain(s) the full routing table. All other nodes in

the domain only maintain their list of parents and use this as a list of default routes toward the border router. This

abbreviated routing table saves memory space and CPU. When communicating in non-storing mode, a node always

forwards its packets to the border router, which knows how to ultimately reach the final destination.

destination Oriented Directed Acyclic Graph

DODAG root is a border router of the RPL domain, Connects the LLN to a backbone network

Parents provide a path to the root

Rank of a node is a scalar representation of the node location

within a DODAG

Used to avoid and detect loops

Objective Function is the objective of the Linear Programming Problem as the name suggests. In linear programming or linear optimization, we use various techniques and methods to find the optimal solution to the linear problem with some constraints. The technique can also include inequality constraints as well. The objective function in Linear Programming is to optimize to find the optimum solution for a given problem.