Information

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

Tags

Sign in

IPv6 : Hop Limit field with traceroute6

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. traceroute6 is a popular debugging tool that allows to trace the path towards a destination.


Usage of Hop Limit by traceroute6

Can you infer the Hop Limit value of the packets captured during the following traceroute6:

traceroute6 -q 1 -n www.ietf.org
traceroute6: Warning: www.ietf.org.cdn.cloudflare.net has multiple addresses; using 2606:4700:10::6814:155
traceroute6 to www.ietf.org.cdn.cloudflare.net (2606:4700:10::6814:155) from 2a02:2788:484:59e:2c1c:849e:f74f:e233, 64 hops max, 12 byte packets
1  2a02:2788:484:59e:a221:b7ff:fed8:aa90  2.415 ms
2  2a02:2788:480::1  8.138 ms
3  2a02:2788:480:2::1  9.125 ms
4  2a02:2788:ffff:1b::1  9.757 ms
5  2001:7f8:26::a501:3335:1  7.960 ms
6  2400:cb00:78:1024::a29e:e959  7.934 ms
# Length Summary Status
0 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33435  
1 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33436  
2 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33437  
3 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33438  
4 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33439  
5 48 bytes User Datagram Protocol, Src Port: 53634, Dst Port: 33440  

0000  6007d0ed001411??  2a0227880484059e  
0010  2c1c849ef74fe233  2606470000100000  
0020  0000000068140155  d182829b00141a84  

0000  `.Ðí...?*.'.....
0010  ,...÷Oâ3&.G.....
0020  ....h..UÑ.......
  • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
    • 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)
          • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
            • Payload Length: 20
              • Next Header: UDP (17)
                • Hop Limit: ?
                • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                  • Destination: 2606:4700:10::6814:155
                  • User Datagram Protocol, Src Port: 53634, Dst Port: 33435
                    • Source Port: 53634
                      • Destination Port: 33435
                        • Length: 20
                          • Checksum: 0x1a84 [unverified]
                          0000  6007d0ed001411??  2a0227880484059e  
                          0010  2c1c849ef74fe233  2606470000100000  
                          0020  0000000068140155  d182829c00141170  

                          0000  `.Ðí...?*.'.....
                          0010  ,...÷Oâ3&.G.....
                          0020  ....h..UÑ......p
                          • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
                            • 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)
                                  • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
                                    • Payload Length: 20
                                      • Next Header: UDP (17)
                                        • Hop Limit: ?
                                        • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                                          • Destination: 2606:4700:10::6814:155
                                          • User Datagram Protocol, Src Port: 53634, Dst Port: 33436
                                            • Source Port: 53634
                                              • Destination Port: 33436
                                                • Length: 20
                                                  • Checksum: 0x1170 [unverified]
                                                  0000  6007d0ed001411??  2a0227880484059e  
                                                  0010  2c1c849ef74fe233  2606470000100000  
                                                  0020  0000000068140155  d182829d0014f0b3  

                                                  0000  `.Ðí...?*.'.....
                                                  0010  ,...÷Oâ3&.G.....
                                                  0020  ....h..UÑ.....ð³
                                                  • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
                                                    • 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)
                                                          • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
                                                            • Payload Length: 20
                                                              • Next Header: UDP (17)
                                                                • Hop Limit: ?
                                                                • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                                                                  • Destination: 2606:4700:10::6814:155
                                                                  • User Datagram Protocol, Src Port: 53634, Dst Port: 33437
                                                                    • Source Port: 53634
                                                                      • Destination Port: 33437
                                                                        • Length: 20
                                                                          • Checksum: 0xf0b3 [unverified]
                                                                          0000  6007d0ed001411??  2a0227880484059e  
                                                                          0010  2c1c849ef74fe233  2606470000100000  
                                                                          0020  0000000068140155  d182829e0014cd01  

                                                                          0000  `.Ðí...?*.'.....
                                                                          0010  ,...÷Oâ3&.G.....
                                                                          0020  ....h..UÑ.....Í.
                                                                          • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
                                                                            • 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)
                                                                                  • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
                                                                                    • Payload Length: 20
                                                                                      • Next Header: UDP (17)
                                                                                        • Hop Limit: ?
                                                                                        • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                                                                                          • Destination: 2606:4700:10::6814:155
                                                                                          • User Datagram Protocol, Src Port: 53634, Dst Port: 33438
                                                                                            • Source Port: 53634
                                                                                              • Destination Port: 33438
                                                                                                • Length: 20
                                                                                                  • Checksum: 0xcd01 [unverified]
                                                                                                  0000  6007d0ed001411??  2a0227880484059e  
                                                                                                  0010  2c1c849ef74fe233  2606470000100000  
                                                                                                  0020  0000000068140155  d182829f0014acdc  

                                                                                                  0000  `.Ðí...?*.'.....
                                                                                                  0010  ,...÷Oâ3&.G.....
                                                                                                  0020  ....h..UÑ.....¬Ü
                                                                                                  • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
                                                                                                    • 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)
                                                                                                          • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
                                                                                                            • Payload Length: 20
                                                                                                              • Next Header: UDP (17)
                                                                                                                • Hop Limit: ?
                                                                                                                • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                                                                                                                  • Destination: 2606:4700:10::6814:155
                                                                                                                  • User Datagram Protocol, Src Port: 53634, Dst Port: 33439
                                                                                                                    • Source Port: 53634
                                                                                                                      • Destination Port: 33439
                                                                                                                        • Length: 20
                                                                                                                          • Checksum: 0xacdc [unverified]
                                                                                                                          0000  6007d0ed001411??  2a0227880484059e  
                                                                                                                          0010  2c1c849ef74fe233  2606470000100000  
                                                                                                                          0020  0000000068140155  d18282a000148b22  

                                                                                                                          0000  `.Ðí...?*.'.....
                                                                                                                          0010  ,...÷Oâ3&.G.....
                                                                                                                          0020  ....h..UÑ......"
                                                                                                                          • Internet Protocol Version 6, Src: 2a02:2788:484:59e:2c1c:849e:f74f:e233, Dst: 2606:4700:10::6814:155
                                                                                                                            • 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)
                                                                                                                                  • .... .... .... 0111 1101 0000 1110 1101 = Flow Label: 0x7d0ed
                                                                                                                                    • Payload Length: 20
                                                                                                                                      • Next Header: UDP (17)
                                                                                                                                        • Hop Limit: ?
                                                                                                                                        • Source: 2a02:2788:484:59e:2c1c:849e:f74f:e233
                                                                                                                                          • Destination: 2606:4700:10::6814:155
                                                                                                                                          • User Datagram Protocol, Src Port: 53634, Dst Port: 33440
                                                                                                                                            • Source Port: 53634
                                                                                                                                              • Destination Port: 33440
                                                                                                                                                • Length: 20
                                                                                                                                                  • Checksum: 0x8b22 [unverified]