Understanding IoT Networks and Devices

• Estimated 20-50 billion devices existed by 2018
• The integration of existing, smart, and constrained nodes within a framework is the reason for the estimation

Connectivity Features

• Connectivity features, such as cellular, Wi-Fi, and ethernet
• Connectivity features include upcoming tech like Bluetooth Low Energy (BLE), DASH7, Insteon and IEEE 802.15.4

ITU's Vision

• The ITU vision is approaching reality, as networked devices have outnumbered humans

IoT LAN

• Local, short-range communication that may or may not connect to the Internet within a building or organization.

IoT WAN

• Connects various network segments organizationally and geographically, and connects to the internet.

IoT Node

• Connected to other nodes inside a LAN via IoT LAN and sometimes to the internet through a WAN directly

IoT Gateway

• A router connecting the IoT LAN to a WAN to the Internet that implements several LAN and WAN forwards packets between LAN and WAN on the IP layer.

IoT Proxy

• Performs active application layer functions between IoT nodes and other entities.

Green Circles

• Nodes represented by green circles correlate to "L" (local link addresses or LU (local link addresses which are unique locally).

Node Addresses

• Nodes within a gateway's jurisdiction have addresses that are valid only within the gateway's domain.
• The same addresses may be repeated in the domain of another gateway
• The gateway has a unique network prefix for globally identifying it.
• This saves unnecessary address wastage, although nodes must communicate to the internet by the gateway.

Local Addresses

• IoT address conservation uses local addresses within the gateway's domain, represented by circles.

Internet Connection

• The internet connected network has routers with their sets of addresses and ranges.

Multiple Gateways

• These routers have multiple gateways to forward packets from the nodes to the Internet, assigning prefixes to gateways for identification.

Network Prefix

• Network prefix changes from 1 to 2 due to movement
• Makes the IoT LAN safe from changes from movements
• IoT gateway WAN address changes without change in LAN address, using ULA

Prefix Assignments

• Gateways assigned with prefixes are attached to a remote anchor point using Mobile IPv6 and are immune to network prefix changes.
• Achieved using LU, the address of the nodes within the gateways remain unchanged
• The locally unique address and change in gateway's network prefix doesn't affect them

Tunneling

• There is a need for nodes to communicate directly to the internet
• Achieved by tunneling to a remote anchor point instead of channeling packets through the router
• Tunneling protocols (IKEv2: internet key exchange version 2) are used

Gateway Responsibility

• IoT gateways, with/without proxies, are mainly responsible for Internet and IoT LAN intra-connectivity

Upstream and Delegation

• Address prefixes are obtained using DHCPv6 and delegated using SLAAC (stateless addressing)

LU Address

• LU addresses are maintained independently of globally routable addresses, for the sake of internal address stability

LU and Internet

• Despite providing address stability, LU cannot communicate directly with the internet/upper layers
• Solved by implementing an application layer proxy
• Application layer proxies can be configured to process or pass data

Intensive Tasks

• For nodes lacking support for computationally intensive tasks, the IoT proxy gathers data sent to the link-local multicast address and routes them globally

IPv4 vs IPv6

• The Internet is mainly IPv4 with little IPv6 uplink facilities
• Lack of IPv6 transition solutions lead to un-optimized IoT deployment
• The translation solutions mainly address IPv6 to IPv4 translation, IPv6 tunneling over IPv4 and application layer proxies (data relaying)

Multi-Homing

• A node or network connected to multiple networks to improve reliability
• Proxy based approach manages multiple IP addresses by mapping them to link local addresses
• Gateway-based approach assigns link local addresses to the nodes under it
• Multi-homing networks present challenges by providing source addresses, destination addresses, and routing information to multi-homed nodes
• Routing between gateways can be used if destination and source addresses come from the same prefix
• The IETF is trying to standardize this issue

IPv4 vs IPv6 differences

• Developed: IPv4 (IETF 1974), IPv6 (IEF 1998)
• Length: IPv4 (32 bits), IPv6 (128 bits)
• No. of Addresses: IPv4 (2^32), IPv6 (2^128)
• Notation: IPv4 (Dotted Decimal), IPv6 (Hexadecimal)
• Dynamic Allocation: IPv4 (DHCP), IPv6 (SLAAC/ DHCPv6)
• IPSec: IPv4 (Optional), IPv6 (Compulsory)
• Header Size: IPv4 (Variable), IPv6 (Fixed)
• Header Checksum and Options: IPv4 (Yes), IPv6 (No)
• Multicast Address: IPv4 (No), IPv6 (Yes)
• Broadcasts Addresses: IPv4 (Yes), IPv6 (No)

IPv4 Header

• Consists of Version (Ver), Internet Header Length (IHL), Type of Service, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol, Header Checksum, Source Address (32 bit), Destination Address (32 bit), Options, Padding

IPv4 Transmission

• Emphasis on reliable transmission is evident by fields like type of service, total length, ID, offset, TTL, and checksum.

IPv6 Header

• Consists of Version (Ver), Traffic Class, Flow Label, Payload Length, Next Header, Hop Limit, Source Address (128 bit), and Destination Length (128 bit)

IPv6 Focus

• Simpler header structure that focuses on addressing the source and destination
• More concerned with addressing than data delivery reliability