6 lowpan
- 1. 6LoWPAN By G.Sivakumar, Assistant Professor, Ramco Institute of Technology, Rajapalayam.
- 2. 6LoWPAN • 6LoWPAN is connecting more things to the cloud. Low-power, IP-driven nodes and large mesh network support make this technology a great option for Internet of Things (IoT) applications. • As the full name implies – “IPv6 over Low-Power Wireless Personal Area Networks” • 6LoWPAN is a networking technology or adaptation layer that allows IPv6 packets to be carried efficiently within small link layer frames, such as those defined by IEEE 802.15.4.
- 3. 6LoWPAN • It use of an end-to-end, IP-based infrastructure takes full advantage of 30+ years of IP technology development • 6LoWPAN is an open standard defined in RFC 6282 by the Internet Engineering Task Force (IETF), the standards body that defines many of the open standards used on the Internet such as UDP, TCP and HTTP. • A powerful feature of 6LoWPAN is that while originally conceived to support IEEE 802.15.4 low-power wireless networks in the 2.4-GHz band
- 5. 6LoWPAN Network Architecture • The uplink to the Internet is handled by the Access Point (AP) acting as an IPv6 router. • Several different devices are connected to the AP in a typical setup, such as PCs, servers, etc. The 6LoWPAN network is connected to the IPv6 network using an edge router. The edge router handles three actions: 1) The data exchange between 6LoWPAN devices and the Internet (or other IPv6 network); 2) Local data exchange between devices inside the 6LoWPAN; 3) The generation and maintenance of the radio subnet (the 6LoWPAN network).
- 6. 6LoWPAN network architecture • By communicating natively with IP, 6LoWPAN networks are connected to other networks simply using IP routers. • As shown in Figure, 6LoWPAN networks will typically operate on the edge, acting as stub networks. This means data going into the network is destined for one of the devices inside the 6LoWPAN. • One 6LoWPAN network may be connected to other IP networks through one or more edge routers that forward IP datagrams between different media. • Connectivity to other IP networks may be provided through any arbitrary link, such as Ethernet, Wi-Fi or 3G/4G.
- 7. 6LoWPAN network architecture • Two other device types are included inside a typical 6LoWPAN network: routers and hosts. Routers can, as the name implies, route data destined to another node in the 6LoWPAN network. • Hosts are also known as end devices and are not able to route data to other devices in the network. Host can also be a sleepy device, waking up periodically to check its parent (a router) for data, enabling very low power consumption.
- 8. System stack overview • An adaptation layer between the IP stack’s link and network layers to enable transmission of IPv6 datagrams over IEEE 802.15.4 radio links.
- 9. System stack overview • All communications systems use a set of rules or standards to format data and control the exchange. The most common model in data communication systems is the Open Systems Interconnect (OSI) model, which in a simplified model, breaks the communication into five fundamental layers. • Figure 2 shows this simplified OSI model alongside two typical examples of stacks used in IoT devices. One is a device running the Wi-Fi stack, the other device is an IoT-connected device based on 6LoWPAN.
- 10. System stack overview • The physical layer converts data bits into signals that are transmitted and received over the air. In the 6LoWPAN example, IEEE 802.15.4 is used. • In addition to the well-rounded 2006 version of the standard, two important amendments exist: e and g. • IEEE 802.15.4e is a MAC amendment and provides enhancements such as time slotted channel hopping (TSCH) and coordinated sampled listening (CSL). Both enhancements aim to further lower the power consumption and make the interface more robust. • The IEEE 802.15.4g is a PHY (or physical layer) and aims to provide an additional range of radio frequency bands to enable worldwide use even in the Sub-1 GHz frequency bands.
- 11. System stack overview • The data link layer provides a reliable link between two directly connected nodes by detecting and correcting errors that may occur in the physical layer during transmission and receiving. • The data link layer includes the media access layer (MAC) which provides access to the media, using features like carrier sense multiple access – collision avoidance (CSMA-CA)
- 12. System stack overview • The network layer addresses and routes data through the network, if needed over several hops. • IP (or Internet Protocol) is the networking protocol used to provide all devices with an IP address to transport packets from one device to another.
- 13. System stack overview • The transport layer generates communication sessions between applications running on end devices. The transport layer allows multiple applications on each device to have their own communications channel. • TCP is the dominant transport protocol on the Internet. However, TCP is a connection-based protocol (including packet ordering) with large overhead and therefore not always suitable for devices demanding ultra-low power consumption. • For those types of systems, UDP, a lower overhead, connectionless protocol, can be a better option. Secure transport layers examples include TLS (transport layer security) running a top TCP and DTLS, which is based on UDP
- 14. System stack overview • The application layer is responsible for data formatting. It also makes sure that data is transported in application-optimal schemes. • A broadly used application layer on the Internet is HTTP running over TCP. HTTP uses XML, which is a text-based language with a large overhead. Therefore, it is not optimal to use HTTP in many 6LoWPAN systems. However, HTTP can still be very useful for communications between 6LoWPAN and the Internet • For this reason, the industry and community have developed alternative application layer protocols, such as the constrained application protocol (COAP), a message protocol running over UDP with a bit-optimized REST mechanism very similar to HTTP.
- 15. System stack overview Need for adaptation layer : • The adaptation layer is the main component of 6LoWPAN. The major function of this layer is 1. The TCP/IP header compression and compression. 2. Fragmentstion and reassembly of packets 3. Routing • The IEEE 802.15.4 frame has a maximum packet size of 128 bytes, whereas IPv6 header size is 40 bytes, User Datagram Protocol (UDP) and Internet Control Message Protocol (ICMP) header sizes are both 4 bytes, fragmentation header adds another 5 bytes overhead. However, without compression, it is not possible to transmit any payload effectively. •
- 16. System stack overview • A second major function of the adaptation layer is to handle packet fragmentation and reassembling. IEEE 802.15.4 has a maximum frame size of 128 bytes, while IPv6 requires a maximum transmission unit (MTU) of 1280 bytes. This mismatch is handled in the adaptation layer. • Routing is the ability to send a data packet from one device to another device, sometimes over multiple hops. Two categories of routing are defined: mesh-under and route-over. Mesh-under uses the layer-two (link layer) addresses (IEEE 802.15.4 MAC to forward data packets. In route-over networks the routing takes place at the IP level ,In this each hop in such networks represents one IP router. The most widely used routing protocol for route-over 6LoWPAN networks today is RPL (pronounced “ripple”).
- 17. 6LowPAN Security • It uses AES -128 Link layer security which is defined in IEEE802.15.4. • It provides link authentication and encryption. • For more security, Transport layer UDP based DTLS (Datagram transport layer security) protocol is used.
- 18. Applications of 6LoWPAN • Automation- used in many different areas of automation. • Used for data monitoring and analyses in industries • The smart grid enabling smart meters and other devices to build a micro mesh network before sending the data back to the billing system using the IPv6 backbone.
- 19. Reference 6LoWPAN demystified – texas Instruments