Summary
Highlights
This chapter focuses on IPv6 addressing, covering everything necessary to understand and work with it. The content will be delivered through multiple videos, emphasizing the importance of taking notes for homework submission.
In the late 1980s and early 1990s, the Internet Engineering Task Force (IETF) recognized the impending exhaustion of IPv4 addresses. IPv4, with its 32-bit addresses, provided only 4.3 billion addresses, which quickly became insufficient due to the exponential growth of internet users. Technologies like NAT extended IPv4's lifespan but introduced delays, particularly for real-time communications. All five Regional Internet Registries (RIRs) have now exhausted their IPv4 addresses, underscoring the critical need for a new addressing scheme.
IPv6, ratified in 1998, offers numerous advantages. It uses 128-bit addresses, providing an immense number of unique addresses and eliminating the need for complex subnetting (allowing for over 65,000 subnets). It features less packet overhead, leading to faster routing and better Quality of Service (QoS), crucial for real-time applications like VoIP and video streaming. IPv6 also includes inherent IP security (IPsec), providing built-in encryption and authentication. It enables global IP addresses, reducing the need for NAT and its associated delays. DHCP is less critical as devices can self-configure IP addresses. Broadcasting is replaced by more efficient unicast and multicast, and devices can have multiple IP addresses on a single network interface card (NIC). Device configuration is also significantly simpler.
An IPv6 address is a 128-bit number written in hexadecimal notation, separated by colons. Each 16-bit segment (called a hextet) consists of four hexadecimal digits. A global unicast address (GUA) is structured into three main parts: the first 48 bits form the global routing prefix (identifying the RIR, ISP, and site), the next 16 bits are for subnetting, and the last 64 bits make up the interface ID (for host identification).
To simplify writing long IPv6 addresses, leading zeros in each hextet can be omitted (e.g., '002A' becomes '2A'). Additionally, a double colon (::) can represent one or more consecutive hextets of all zeros, but this can only be used once in an address to avoid ambiguity. The video concludes by emphasizing the importance of understanding these rules for rewriting IPv6 addresses concisely.