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Author(s) Olivier Bonaventure
Deadline No deadline
Submission limit No limitation
Category tags IPv6

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IPv6 : ping6, a simple example

ICMPv6, described in the IPv6 chapter of Computer Networking: Principles, Protocols and Practice is a companion protocol for IPv6 that is used for various functions including network debugging. ping6 is a popular debugging tool that allows to verify whether a remote host is up and running. For this, it sends an ICMPv6 Echo request that contains some information and waits for an ICMPv6 Echo reply.


ping6 messages

Can you infer the Identifier and the sequence fields of the ICMPv6 Echo response ?

# Length Summary Status
0 48 bytes Internet Control Message Protocol v6
1 48 bytes Internet Control Message Protocol v6  

0000  6006f53600103a40  200106a8308f0002  
0010  48e995ae3a92922d  200106a830810001  
0020  0000000000000002  800088ac3a830000  

0000  `.õ6..:@ ..¨0...
0010  Hé.®:..- ..¨0...
0020  ...........¬:...
  • Internet Protocol Version 6, Src: 2001:6a8:308f:2:48e9:95ae:3a92:922d, Dst: 2001:6a8:3081:1::2
    • 0110 .... = Version: 6
      • .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
        • .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
          • .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
          • .... .... .... 0110 1111 0101 0011 0110 = Flow Label: 0x6f536
            • Payload Length: 16
              • Next Header: ICMPv6 (58)
                • Hop Limit: 64
                  • Source: 2001:6a8:308f:2:48e9:95ae:3a92:922d
                    • Destination: 2001:6a8:3081:1::2
                    • Internet Control Message Protocol v6
                      • Type: Echo (ping) request (128)
                        • Code: 0
                          • Checksum: 0x88ac [correct]
                            • Identifier: 0x3a83
                              • Sequence: 0
                              0000  6006f53600103a3d  200106a830810001  
                              0010  0000000000000002  200106a8308f0002  
                              0020  48e995ae3a92922d  810087ac????????  

                              0000  `.õ6..:= ..¨0...
                              0010  ........ ..¨0...
                              0020  Hé.®:..-...¬????
                              • Internet Protocol Version 6, Src: 2001:6a8:3081:1::2, Dst: 2001:6a8:308f:2:48e9:95ae:3a92:922d
                                • 0110 .... = Version: 6
                                  • .... 0000 0000 .... .... .... .... .... = Traffic Class: 0x00 (DSCP: CS0, ECN: Not-ECT)
                                    • .... 0000 00.. .... .... .... .... .... = Differentiated Services Codepoint: Default (0)
                                      • .... .... ..00 .... .... .... .... .... = Explicit Congestion Notification: Not ECN-Capable Transport (0)
                                      • .... .... .... 0110 1111 0101 0011 0110 = Flow Label: 0x6f536
                                        • Payload Length: 16
                                          • Next Header: ICMPv6 (58)
                                            • Hop Limit: 61
                                              • Source: 2001:6a8:3081:1::2
                                                • Destination: 2001:6a8:308f:2:48e9:95ae:3a92:922d
                                                • Internet Control Message Protocol v6
                                                  • Type: Echo (ping) reply (129)
                                                    • Code: 0
                                                      • Checksum: 0x87ac [correct]
                                                        • Identifier: ?
                                                        • Sequence: ?