I don't understand what it is meant for "streamlined ipv6 header"? Could you please provide an example?

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IPv4 has a lot of fields (14) in the header:

  • Version

  • IHL: Internet Header Length.

  • DSCP: Type of Service.

  • ECN: Explicit Congestion Notification.

  • Total Length: Length of entire IP Packet.

  • Identification: An identification number for fragmented packets.

  • Flags

  • Fragment Offset: Position of the fragment in the original Packet.

  • Time to Live.

  • Protocol: Next level Protocol. (UDP, TCP, etc.).

  • Header Checksum

  • Source Address

  • Destination Address

  • Options

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IPV6 designers have reduced this complexity (streamlined the header) to make it easier for routers and network systems to verify each packet and forward it using a routing table.

The IPV6 header has the following 8 fields:

  • Version

  • Traffic Class: 8-bits, the most significant 6 bits are Type of Service and the remaining 2 are used for Explicit Congestion Notification (ECN).

  • Flow Label: Used to maintain the sequential flow of the packets belonging to a communication. The source labels the sequence to help the router identify that a particular packet belongs to a specific flow of information. This field helps avoid re-ordering of data packets. It is designed for streaming/real-time media.

  • Payload Length: Payload is composed of Extension Headers and Upper Layer data.

  • Next Header: Indicates either the type of Extension Header, or if the Extension Header is not present then it indicates the Upper Layer.

  • Hop Limit: This is the same as TTL on IPv4.

  • Source Address (128-bits).

  • Destination Address (128-bits).

The IPv6 header format was designed to keep the header overhead to a minimum.

The non-essential fields and optional fields were moved to extension headers that are placed after the IPv6 header. The IPv6 header can be processed more efficiently at intermediate routers.

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