NAME

  receiveMTU0 - Verify that a node does not reduce its estimate of the Path 
                MTU  below the IPv6 minimum link MTU.

TARGET

  Host and Router

SYNOPSIS

  receiveMTU0.seq [-tooloption ...] -pkt receiveMTU0.def
    -tooloption : v6eval tool option

INITIALIZATION

        If the NUT is a host, send a Router Advertisment.
        If the NUT is a router, configure a default route with TN as the next hop.
        And make state of Neighbor Cashe Entry for TN's addresses reachable.

TEST PROCEDURE

   TN2                    TR1                    NUT
    |                      |                      |
    |-------------------------------------------->|
    |   1.Echo Request     |                      |
    |   (1280 octets)      |                      |
    |                      |                      |
    |<--------------------------------------------|
    |   2.Echo Reply       |                      |
    |   (1280 octets)      |                      |
    |                      |                      |
    |                      +--------------------->|
    |                      |  3.Packet Too Big    |
    |                      |    (MTU 0)           |
    |                      |                      |
    |-------------------------------------------->|
    |   4.Echo Request     |                      |
    |   (1280 octets)      |                      |
    |                      |                      |
    |<--------------------------------------------|
    | 5.Echo Reply         |                      |
    |   (1288 octets)      |                      |
    |                      |                      |
    v                      v                      v

  1. Send Echo Request
  2. Receive Echo Reply <<Check 1>>
  3. Send Packet Too Big message
  4. Send Echo Request
  5. Receive Echo Reply(include Fragment Header) 
     or  fragmented Echo Reply <<Check 2>>

  Echo Request Data is:

        IPv6 Header
            Version            = 6
            Traffic Class      = 0
            FlowLabel          = 0
            PayloadLength      = 1240
            NextHeader         = 58 (ICMPv6)
            SourceAddress      = TN2's Global Address
            DestinationAddress = NUT's Global Address

        ICMP Echo Request
            Type           = 128 (Echo Request)
            Code           = 0
            Checksum       = (auto)
            Identifier     = 0xffff
            SequenceNumber = 1
            PayloadData    = (1232 octets)

  Packet Too Big message is:

        IPv6 Header
            Version            = 6
            Traffic Class      = 0
            FlowLabel          = 0
            PayloadLength      = 1280
            NextHeader         = 58 (ICMPv6)
            SourceAddress      = TR1's Global Address
            DestinationAddress = NUT's Global Address

        ICMP Echo Request
            Type           = 2 (Packet Too Big)
            Code           = 0
            Checksum       = (auto)
            MTU            = 0
            PayloadData    = (1232 octets)

JUDGEMENT

  PASS: <<Check 1>> Echo Reply Received or Fragment Echo Reply Received
        <<Check 2>> Echo Reply which include Fragment Header Received, or 
                    Fragment Echo Reply Received.

        IPv6 Header
            Version             = 6
            Traffic Class       = 0
            FlowLabel           = 0
            PayloadLength       = 1240
            NextHeader          = 58 (ICMPv6)
            SourceAddress       = Target Global Address
            Destination Address = TN2's Global Address

        ICMP Echo Reply
            Type           = 129 (Echo Reply)
            Code           = 0
            Checksum       = (auto)
            Identifier     = 0xffff (same as Echo Request)
            SequenceNumber = 1 (same as Echo Request)
            PayloadData    = (1232 octets) (same as Echo Request)

REFERENCE

RFC 1981 - Path MTU Discovery for IPv6