NAME

        rfc2766_5.3.2_checksum_icmp.seq - Verify IPv6 <-> IPv4 header 
        translation in accordance with RFC2766 [NATPT]

TARGET

        Router

SYNOPSIS

        rfc2766_5.3.2_checksum_icmp.seq [-tooloption ...] 
        -p rfc2766_5.3.2_checksum_icmp.def

INITIALIZATION

	Before this test starts, run initialize_natpt.seq.

TEST PROCEDURE

        This test verifies that NUT adjusts header checksum for ICMP packets.
        
        Network Topology

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

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

        1.1.
        ===================>
        IPv6 ICMP packet
                IPv6 Header
                        src address : TN LINK0 IPv4 embedded IPv6 address
                        dst address : TN LINK1 IPv4 embedded IPv6 address
                ICMPv6 Destination Unreachable
                        Type = 1
                        Code = 0
                Payload (48 bytes)
                        IPv6 Header (40 bytes)
                                src address : TN LINK0 IPv4 embedded IPv6 address
                                dst address : TN LINK1 IPv4 embedded IPv6 address
                                NextHeader = 17
                        UDP packet (first 8 bytes)
                                Checksum including IPv6 pseudo header
                                data = repeat(0xff,1422)
        1.2.
        <<JUDGMENT>>
                                   ===================>
        IPv4 ICMP packet
                IPv4 Header
                        src address : TN LINK0 IPv4 address
                        dst address : TN LINK1 IPv4 address
                        DF = 1
                ICMPv4 Destination Unreachable
                        Type = 3
                        Code = 1
                Payload (28 bytes)
                        IPv4 Header (20 bytes)
                                src address : TN LINK0 IPv4 address
                                dst address : TN LINK1 IPv4 address
                                DF = 1
                                Protocol = 17
                        UDP packet (first 8 bytes)
                                Checksum including IPv4 pseudo header
                                data = repeat(0xff,1422)

JUDGMENT

        << PASS >>
                NUT will translate ICMPv6 Destination Unreachable
                to ICMPv4 Destination Unreachable.
                NUT will translate the inner IPv6 UDP packet to the
                equivalent IPv4 UDP packet.
                NUT will update checksums for the inner and outer
                IP headers.
                
        << FAIL >>      
                NUT does not translate correctly.

NOTE

REFERENCE

RFC2766

5.3.2 TCP/UDP/ICMP Checksum Update from IPv6 to IPv4

   The checksum calculation for a V4 ICMP header needs to be derived
   from the V6 ICMP header by running the checksum adjustment algorithm
   [NAT] to remove the V6 pseudo header from the computation. Note, the
   adjustment must additionally take into account changes to the
   checksum as a result of updates to the source and destination
   addresses (and transport ports in the case of NAPT-PT) made to the
   payload carried within ICMP.