NAME

  IP_HL_DecrementIN - Hop Limit Decrement - Intermediate Node (Router Only)

TARGET

  Router

SYNOPSIS

  IP_HL_DecrementIN.seq [-tooloption ...] -pkt IP_HL_DecrementIN.def
    -tooloption : v6eval tool option

INITIALIZATION

  None

TEST PROCEDURE

Verify that a router correctly processes the Hop Limit field of received packets an generates a valid value in transmitted packets.

   TN1                         RUT                         TN2
              (Link0)                     (Link1)
    |                           |                           |
    |-------------------------->|                           |
    |   Echo Request to Link0   |                           |
    |      (Hop Limit = 15)     |                           |
    |                           |-------------------------->|
    |                           |   Echo Request to Link1   |
    |                           |      (Hop Limit = 14)     |
    |                           |                           |
    v                           v                           v

  1. TN1 transmits an Echo Request to TN'2s Global Address with a first hop through the RUT.
     The Hop Limit field is set to 15.
  2. Observe the packets transmitted by the RUT on Link1.

  Echo Request to Link0 Data is:

        IPv6 Header
            Version            = 6
            Traffic Class      = 0
            FlowLabel          = 0
            PayloadLength      = 16
            NextHeader         = 58 (ICMPv6)
            HopLimit           = 15
            SourceAddress      = TN1 Global Address (Link0)
            DestinationAddress = TN2 Global Address (Link1)

        ICMP Echo Request
            Type           = 128 (Echo Request)
            Code           = 0
            Checksum       = (auto)
            Identifier     = 0xffff
            SequenceNumber = 1
            PayloadData    = {1, 2, 3, 4, 5, 6, 7, 8}

JUDGEMENT

  PASS: The RUT should forward the Echo Request to TN2.
        The Hop Limit field should be decremented 14.

        IPv6 Header
            Version             = 6
            Traffic Class       = 0
            FlowLabel           = 0
            PayloadLength       = 16
            NextHeader          = 58 (ICMPv6)
            HopLimit            = 14
            SourceAddress      = TN1 Global Address (Link0)
            DestinationAddress = TN2 Global Address (Link1)

        ICMP Echo Request
            Type           = 128 (Echo Request)
            Code           = 0
            Checksum       = (auto)
            Identifier     = 0xffff
            SequenceNumber = 1
            PayloadData    = {1, 2, 3, 4, 5, 6, 7, 8}

CLEANUP

Common Test Cleanup

REFERENCE

RFC 8200 - IPv6 Specification