Modull 12-IPv4 vs IPv6 Comparison and Address Types

IPv4 vs IPv6 Comparison

• IPv4 has a limited address space of about 4.3 billion unique addresses, making it insufficient for the increasing number of internet users and devices.
• Network Address Translation (NAT) and private addresses helped delay the depletion of IPv4 addresses, but IPv6 was developed as a more permanent solution.
• IPv4 and IPv6 will co-exist for a transition period.
• The Internet Engineering Task Force (IETF) created methods for migrating from IPv4 to IPv6.

IPv6 Address Representation

• IPv6 addresses are 128 bits long.
• Usually written as eight groups of four hexadecimal digits (e.g., 2001:0db8:0000:1111:0000:0000:0000:0200).
• Leading zeros can be omitted (e.g., 0000 becomes 0).
• A double colon (::) can replace a series of zero groups (e.g., 2001:db8:0:1111::200).

IPv6 Address Types

• Unicast: For a single interface (a unique IPv6 address on a device).
• Multicast: For a group of devices.
• Anycast: Enables multiple devices to share one address, directing traffic to the nearest device with that address.
• IPv6 uses slash notation (e.g., /64) to specify the network portion (prefix).

Global Unicast and Link-Local Addresses (GUA & LLA)

• Devices usually have two unicast addresses:
  • Global Unicast Address (GUA): Routable on the internet.
  • Link-Local Address (LLA): Operates only on the local network.
• Unique local addresses act like private addresses in IPv4, for use within a site or small networks.
• GUAs and LLAs can be configured statically or dynamically.

Dynamic Addressing for IPv6 GUAs

• Devices can automatically obtain IPv6 GUAs using ICMPv6 messages.
• Router Advertisement (RA) messages: Sent by routers to devices on the network.
• Router Solicitation (RS) message: Sent by a device to request RA information.
• Address assignment methods include:
  • Stateless Address Autoconfiguration (SLAAC): Device generates its own address using prefix and interface ID from RA.
  • SLAAC + Stateless DHCPv6: Device uses SLAAC for addresses but gets additional information (e.g., DNS) from a stateless DHCPv6 server.
  • Stateful DHCPv6: Device requests an address from a DHCPv6 server (similar to IPv4 DHCP).
• Interface ID generation: EUI-64 (based on MAC address), or random 64-bit number.

Dynamic Addressing for IPv6 LLAs

• Every IPv6 device has a link-local address (LLA).
• LLAs can be manually assigned or automatically created.
• Many routers automatically generate LLAs.

IPv6 Multicast Addresses

• Well-known multicast addresses: Predefined groups (e.g., ff02::1 - all nodes, ff02::2 - all routers).
• Solicited-node multicast address: Used for device MAC address discovery (similar to ARP in IPv4).

IPv6 Subnetting

• IPv6 subnetting is flexible.
• Addresses have a global routing prefix, subnet ID, and interface ID.
• A common prefix size is /48 (global prefix) and /64 (total network), allowing for 65,536 subnets and an enormous number of possible device addresses.
• Subnets are designed logically rather than address-focused.