# NAME

            fragment.seq - Verify that node perform fragmentation inside
            tunnel

# TARGET

            Router

# SYNOPSIS

            fragment.seq [-tooloption ...] -p fragment.def

# INITIALIZATION

    	Before this test starts, run initialize.seq.
    	In subroutine "change_tunnel_mtu" use two way of changeing
    	tunnel's path MTU.
    	If DF flag of encapsulating IPv4 Header isn't set, the test consider
    	that node do not execute IPv4 path MTU. and change node's link MTU.
    	If DF flag of encapsulating IPv4 Header is set, test consider
    	that node execute IPv4 path MTU. and send ICMPv4 Packet Too Big
    	message.

# TEST PROCEDURE

            This test verifies that node can employ fragmentation algorithm
            to determine when to forward an IPv6 packet that is larger than
            the tunnel's path mtu.

        Network Topology

        Link0
        --------------------------
            |               |
           TN              NUT
            |               |
        --------------------------
        Link1

        TN -- (Link0) -- NUT        TN -- (Link1) -- NUT

        ---------------------      ------------------------
        0.
        set tunnel's mtu is 1500

        -- V4PMTU -20 = 1400
        1.1.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1401

        1.1.2
        <<JUDGMENT>>
        <===================
        ICMPv6 Packet Too Big message
            MTU : 1400

        1.2.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1400

        1.2.2
        <<JUDGMENT>>
                                   <===================
        IPv4 packet encapsulating IPv6 packet

        -- V4PMTU -20 = 1280

        2.1.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1400

        2.1.2
        <<JUDGMENT>>
        <===================
        ICMPv6 Packet Too Big message
            MTU : 1280

        2.2.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1281

        2.2.2
        <<JUDGMENT>>
        <===================
        ICMPv6 Packet Too Big message
            MTU : 1280

        2.3.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1280

        2.3.2
        <<JUDGMENT>>
                                   <===================
        IPv4 packet encapsulating IPv6 packet

        -- V4PMTU -20 = 1000
        3.1.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1281

        3.1.2
        <<JUDGMENT>>
        <===================
        ICMPv6 Packet Too Big message
            MTU : 1280

        3.2.1
        ===================>
        ICMPv6 Echo Request
            packet size : 1280

        3.2.2
        <<JUDGMENT>>
                                   <===================
        IPv4 packet encapsulating IPv6 packet

# JUDGMENT

            << PASS >>
                    TN received the packet which describe above "TEST PROCEDURE"

            << FAIL >>
                    TN could not receive the packet which describe above
                    "TEST PROCEDURE"

# SEE ALSO

              perldoc V6evalTool