IPv6 Packets

Explain the role of the major header fields in the IPv6 packet.

Limitations of IPv4

IPv4 has three major limitations:

• IPv4 address depletion – We have basically run out of IPv4 addressing.
• Lack of end-to-end connectivity – To make IPv4 survive this long, private addressing and NAT were created. This ended direct communications with public addressing.
• Increased network complexity – NAT was meant as temporary solution and creates issues on the network as a side effect of manipulating the network headers addressing. NAT causes latency and troubleshooting issues.

IPv6 Overview

• IPv6 was developed by Internet Engineering Task Force (IETF).
• IPv6 overcomes the limitations of IPv4.
• Improvements that IPv6 provides:
• • Increased address space – based on 128 bit address, not 32 bits
  • Improved packet handling – simplified header with fewer fields
  • Eliminates the need for NAT – since there is a huge amount of addressing, there is no need to use private addressing internally and be mapped to a shared public address

IPv4 Packet Header Fields in the IPv6 Packet Header

• The IPv6 header is simplified, but not smaller.
• The header is fixed at 40 Bytes or octets long.
• Several IPv4 fields were removed to improve performance.
• • Flag
  • Fragment Offset
  • Header Checksum

IPv6 Packet Header

• Significant fields in the IPv6 header:

• IPv6 packet may also contain extension headers (EH).
• EH headers characteristics:
• • provide optional network layer information
  • are optional
  • are placed between IPv6 header and the payload
  • may be used for fragmentation, security, mobility support, etc.

Note: Unlike IPv4, routers do not fragment IPv6 packets.

Other related topics

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