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Logical addressing in networking refers to the method of assigning unique addresses to devices within a network to facilitate communication. IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6) are two primary protocols used for logical addressing in IP networks. Let’s explore the address schemes of both IPv4 and IPv6:

IPv4 Address Scheme:

Format:

  • IPv4 addresses are 32 bits long, divided into four 8-bit octets.
  • Each octet is represented in decimal format and separated by periods (dots).
  • Example: 192.0.2.1

Address Classes:

  • IPv4 addresses are categorized into five classes: A, B, C, D, and E.
  • Classes A, B, and C are used for unicast addresses (one-to-one communication), while class D is used for multicast addresses (one-to-many communication), and class E is reserved for experimental use.

Address Types:

  • Unicast Address: Identifies a single network interface within the IP network.
  • Broadcast Address: Used to send data to all devices within a network segment. The broadcast address is typically the highest address in the subnet.
  • Multicast Address: Used to send data to multiple devices interested in receiving the same data. Multicast addresses start with the range 224.0.0.0 to 239.255.255.255.

IPv6 Address Scheme:

Format:

  • IPv6 addresses are 128 bits long, represented in hexadecimal format and separated by colons (:).
  • The longer address space of IPv6 allows for a significantly larger number of unique addresses compared to IPv4.
  • Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Address Types:

  • Unicast Address: Similar to IPv4, identifies a single network interface within the IP network.
  • Multicast Address: Used to send data to multiple devices interested in receiving the same data. IPv6 multicast addresses start with the prefix ff00::/8.
  • Anycast Address: Identifies multiple interfaces, typically belonging to different devices. The packet is delivered to the nearest interface based on routing protocols.

IPv4 to IPv6 Transition:

  • Due to the depletion of IPv4 addresses, IPv6 was introduced to provide a larger address space.
  • Transition mechanisms such as dual-stack, tunneling, and translation are used to facilitate the coexistence of IPv4 and IPv6 networks during the transition period.

Summary:

  • IPv4 addresses are 32 bits long and use decimal notation, while IPv6 addresses are 128 bits long and use hexadecimal notation.
  • IPv4 addresses are divided into classes, while IPv6 addresses have a flat address space.
  • Both IPv4 and IPv6 support unicast, multicast, and anycast addressing. However, IPv6 provides a much larger address space to accommodate the growing number of devices connected to the internet.