IPv4

• Format - 32-bit numbers, usually written in decimal format as four octets separated by periods.
• Range - Can provide approximately 4.3 billion unique addresses.
• Configuration - Can be configured manually (static IP) or automatically (dynamic IP) using Dynamic Host Configuration Protocol (DHCP)
• Header complexity - Simpler header with 12 fields. Security - Security features optional and implemented through IPsec.
• Eg - 192.168.1.1, 172.16.0.1, 10.0.0.1

IPv6

• Format - 128-bit numbers, usually written in hexadecimal format as eight groups of four hexadecimal digits separated by colons.
• Range - Can provide virtually unlimited number of unique addresses (~340 undecillion).
• Configuration - Designed to support auto-configuration. Uses Stateless Address Autoconfiguration (SLAAC) and can also use DHCPv6.
• Header complexity - Complex with 8 fields, but includes additional features like flow labeling and improved routing efficiency.
• Security - IPSec is mandatory. Provided built-in security features.
• Eg - 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Components

• IP Header - Contains information for routing the packet across the network.
• TCP/UDP Header - If packet uses TCP or UDP, additional headers are included after IP header to manage data transmission.

IPv4

• Length: 20-60 bytes (depending on options)
• Fields: 12 mandatory fields
• Structure:
  • Version - (4 bits) Indicates the IP version.
  • IHL (Internet Header Length) - (4 bits) Specifies the header length.
  • Type of Service (ToS) - (8 bits) Defines service quality parameters.
  • Total Length - (16 bits) Total length of the packet (header + data).
  • Identification - (16 bits) Used for packet fragmentation.
  • Flags - (3 bits) Control or identify fragments.
  • Fragment Offset - (13 bits) Position of a fragment in the original packet.
  • Time to Live (TTL) - (8 bits) Limits the packet's lifespan.
  • Protocol - (8 bits) Identifies the next level protocol (e.g., TCP, UDP).
  • Header Checksum - (16 bits) Error-checking of the header.
  • Source Address - (32 bits) IP address of the sender.
  • Destination Address - (32 bits) IP address of the receiver.
  • Options - Variable length, used for additional functionality.

IPv6

• Length: Fixed at 40 bytes (excluding extension headers)
• Fields: 8 mandatory fields
• Structure:
  • Version - (4 bits) Indicates the IP version.
  • Traffic Class - (8 bits) Similar to IPv4's ToS, for QoS handling.
  • Flow Label - (20 bits) Used for identifying packet flows for QoS.
  • Payload Length - (16 bits) Length of the payload (data).
  • Next Header - (8 bits) Identifies the type of the next header (can be another protocol or an extension header).
  • Hop Limit - (8 bits) Equivalent to IPv4's TTL, limits packet lifespan.
  • Source Address - (128 bits) IP address of the sender.
  • Destination Address - (128 bits) IP address of the receiver.
• Structure (non-mandatory):
  • Hop-by-Hop Options Header - Carries information to be examined by every router along the packet's path.
  • Destination Options Header - Carries information to be processed only by the destination node(s).
  • Routing Header - Supports source routing, allowing specification of intermediate nodes.
  • Fragment Header - Manages packet fragmentation, with fragmentation done only by the source node.
  • Authentication Header (AH) - Ensures connectionless integrity and data origin authentication; part of IPsec.
  • Encapsulating Security Payload (ESP) Header - Provides confidentiality, integrity, authentication, and anti-replay; part of IPsec.
  • Mobility Header - Supports mobile nodes in mobile IPv6, handling binding updates and acknowledgments.
  • No Next Header - Indicates the end of the header chain, with payload starting immediately after.

• Determined by the subnet mask.
• In 192.168.1.1*24, the network portion is 192.168.1.

• In 192.168.1.1*24, the host portion is .1.

• Network Portion: 192.168.1
• Host Portion: .1

• Class A:
  • Largest networks and can accommodate over 16 million hosts.
  • Typically used by large corporations or government agencies.
• Class B:
  • Medium-sized networks that can accommodate over 65000 hosts.
  • Typically used by universities or large businesses.
• Class C:
  • Small networks and can accommodate up to 254 hosts.
  • Typically used by small business and home networks.
• Class D:
  • Reserved for multicast addressing, which is used to send data to multiple recipients simultaneously.
• Class E:
  • Experiment and not used for anything specific.