IPv6

https://www.ietf.org/rfc/rfc2460.txt

Sample IPv6 ICMP Packet https://www.cloudshark.org/captures/84fd54ad03e0

IPv6 Packet Header

   IPv6 Header - fixed length of 40 octets, any header extensions are
   included in the payload length 


   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Version| Traffic Class |           Flow Label                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Payload Length        |  Next Header  |   Hop Limit   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                         Source Address                        +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                                                               |
   +                      Destination Address                      +
   |                                                               |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Version              4-bit Internet Protocol version number = 6. [0110] 0x6

   Traffic Class        8-bit traffic class field. DSCP 6bits [000000] + ECN 2bit [00]
                        DSCP Traffic classification (network), and Explicit Congestion Notification    

   Flow Label           20-bit flow label. (under development)

   Payload Length       16-bit unsigned integer.  Length of the IPv6
                        payload, i.e., the rest of the packet following
                        this IPv6 header, in octets.  (Note that any
                        extension headers [section 4] present are
                        considered part of the payload, i.e., included
                        in the length count.)

   Next Header          8-bit selector.  Identifies the type of header
                        immediately following the IPv6 header.  Uses the
                        same values as the IPv4 Protocol field [RFC-1700
                        et seq.]
                          0x003A decimal 58 = ICMPv6 payload
                          0x0006 decimal 6 = TCP segment in payload
                          0x0011 decimal 17 = UDP segment in payload

   Hop Limit            8-bit unsigned integer.  Decremented by 1 by
                        each node that forwards the packet. The packet
                        is discarded if Hop Limit is decremented to
                        zero.

   Source Address       128-bit address of the originator of the packet.
                        See [ADDRARCH].

   Destination Address  128-bit address of the intended recipient of the
                        packet (possibly not the ultimate recipient, if
                        a Routing header is present).  See [ADDRARCH]
                        and section 4.4.

IPv6 Extension Headers

Extension Headers are optional RFX8200

• Type 0 - Hop by hop options
• Type 43 - Routing
• Type 44 - Fragment
• Type 60 - Destination Options
• Type 51 - Authentication (AH)
• Type 50 - Encapsulating Security Payload (ESP)

IPv6 Addresses

Represented in Hexadecimal, there are 8x 4 hexdecimal digits fields mapping to 16 binary bits separated by ':' Each hex digit represents a nibble. IE 0x2 --> 0010 In total 32 hex digita in a IPv6 address --> 128 binary bits

• Leading zeros in any field may be omitted when writing an address
• '::' may be used once to compress adjacent fields that would otherwise only contain zeros,
  • RFC5952 is multiple opportunies to shorten zero bits, the longer should be used, or the left most if the two options are the same length

IPv6 Prefix and URI

ipv6_address/Prefix length prefix length is the left most bits.

2001:db8::/32 --> prefix 2001:0db8
2001:0db8:0000:0000:0000:0000:0000:0000/32

2001:db8:1::36e:1250:2b00/48 --> prefix = 2001:0db8:00001

2001:

RFC3986 - '[]' square brackets are used to enclose the IP liternal