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