2018-10-12 15:37:13 -04:00
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---
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title: IPv6 Header
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---
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## IPv6 Header Format
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2018-10-26 12:11:18 -07:00
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Below is the IPv6 header format according to [RFC2460](https://tools.ietf.org/html/rfc2460):
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2018-10-12 15:37:13 -04:00
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2018-10-26 12:11:18 -07:00
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2018-10-12 15:37:13 -04:00
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2018-10-26 12:11:18 -07:00
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##### Version [4-bits]
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* Internet Protocol (IP) version number (decimal 6, binary 0110)
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##### Traffic Class [8-bits]
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* Identifies different classes or priorities of IPv6 packets
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##### Flow Label [20-bits]
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* Services that require special handling can utilize this field (defaults to all 0's)
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##### Payload Length [16-bits]
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* Specifies the size of the payload including extension headers. Value is measured in Octets (8-bit values)
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##### Next Header [8-bits]
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* Specifies the type of the next header after the IPv6 header
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##### Hop Limit [8-bits]
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* Number of hops before the packet is discarded
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* Value is decremented by each forwarding node in the network. When the value reaches 0, the packet is discarded
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* Maximum hops using 8-bits is `2^8` or 256 hops
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##### Source Address [128-bits]
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* The IPv6 address of the device sending the packet
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##### Destination Address [128-bits]
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* The IPv6 address of the device(s) destined to receive the packet
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* Destination may be more than one host/device when using Multicast/Anycast
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#### More Information:
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* [List of IP protocol numbers used in the Next Header](https://en.wikipedia.org/wiki/List_of_IP_protocol_numbers)
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