#!/usr/bin/perl
#
# $Name: V6LC_P2_1_4_6 $
#
# Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006
# 	Yokogawa Electric Corporation.
# All rights reserved.
# 
# Redistribution and use of this software in source and binary
# forms, with or without modification, are permitted provided that
# the following conditions and disclaimer are agreed and accepted
# by the user:
# 
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in
#    the documentation and/or other materials provided with
#    the distribution.
# 
# 3. Neither the names of the copyrighters, the name of the project
#    which is related to this software (hereinafter referred to as
#    "project") nor the names of the contributors may be used to
#    endorse or promote products derived from this software without
#    specific prior written permission.
# 
# 4. No merchantable use may be permitted without prior written
#    notification to the copyrighters.
# 
# 5. The copyrighters, the project and the contributors may prohibit
#    the use of this software at any time.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHTERS, THE PROJECT AND
# CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING
# BUT NOT LIMITED THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.  IN NO EVENT SHALL THE
# COPYRIGHTERS, THE PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# $Id: storedPMTU.seq,v 1.8 2005/06/02 02:03:07 akisada Exp $
#
######################################################################
BEGIN {
	$V6evalTool::TestVersion = '$Name: V6LC_P2_1_4_6 $';
}

use V6evalTool;
use CommonPMTU;

$pktdesc{'echo_request1500_tn1'}	= "Send Echo Request from TN1 (on-link, $CommonPMTU::default_mtu octets (Media Type Default))";
$pktdesc{'echo_request1500_tn2'}	= "Send Echo Request from TN2 ($CommonPMTU::default_mtu octets (Media Type Default))";
$pktdesc{'echo_request1500_tn3'}	= "Send Echo Request from TN3 ($CommonPMTU::default_mtu octets (Media Type Default))";
$pktdesc{'echo_reply1500_tn1'}		= 'Recv Echo Reply to TN1 (on-link, $CommonPMTU::default_mtu octets (Media Type Default))';
$pktdesc{'echo_reply1500_tn2'}		= 'Recv Echo Reply to TN2 ($CommonPMTU::default_mtu octets (Media Type Default))';
$pktdesc{'echo_reply1500_tn3'}		= 'Recv Echo Reply to TN3 ($CommonPMTU::default_mtu octets (Media Type Default))';
$pktdesc{'PktTooBig1400_tn2'}		= 'Send Packet Too Big message for Echo Reply to TN2';
$pktdesc{'PktTooBig1280_tn3'}		= 'Send Packet Too Big message for Echo Reply to TN3';

$pktdesc{'setup_echo_request_tn1'}	= 'Send Echo Request from TN1 (Global)';
$pktdesc{'setup_echo_reply_tn1'}	= 'Recv Echo Reply to TN1 (Global)';
$pktdesc{'ns_g2g_tn1'}			= 'Recv Neighbor Solicitation to TN1 (Global to Global)';
$pktdesc{'ns_l2g_tn1'}			= 'Recv Neighbor Solicitation to TN1 (Link-Local to Global)';
$pktdesc{'na_g2g_tn1'}			= 'Send Neighbor Advertisement from TN1 (Global to Global)';
$pktdesc{'na_g2l_tn1'}			= 'Send Neighbor Advertisement from TN1 (Global to Link-Local)';

$pktdesc{'cleanup_na_tn1'}		= 'Send Neighbor Advertisement from TN1 (Globaladdress with Different Link-Layer Address)',
$pktdesc{'cleanup_echo_request_tn1'}	= 'Send Echo Request from TN1 (Global)';

$endStatus = $V6evalTool::exitPass;
$IF = 'Link0';

$mtu_diff_min = $CommonPMTU::default_mtu - 1280;
vCPP("-DMTU_DIFF_MIN=$mtu_diff_min");


#fake data
$fragment_id = 0;
$PTB_payload = '_PACKET_IPV6_echo_reply1500_tn1';
$packet_len = 1500;

vCapture($IF);
#======================================================================
if (setup11_v6LC_4_1_2($IF) != $CommonPMTU::Success or additional_setup($IF) != $CommonPMTU::Success) {
	$ret = cleanup($IF);
	if ($ret == $CommonPMTU::Success) {
		exit($V6evalTool::exitFail);
	} else {
		exit($V6evalTool::exitFatal);
	}
}
#======================================================================
#----- test

#----- create fragment pkt.def(from tn1 to nut(onlink))

$original_name = "echo_reply1500_tn1"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_hether_nut_to_onlinkTN1';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN1_GL0_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn1 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn1');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn1',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	if($ret{'recvFrame'} eq 'echo_reply1500_tn1'){
		vLogHTML('OK<BR>');
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
	
	
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);

#----- create fragment pkt.def(from tn2 to nut)

$original_name = "echo_reply1500_tn2"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN2_GL2_ADDR';

$def_file_tn2 = 'pkt_frag_tn2.def'; #fragment define file


#write def file
if(writefragdef($def_file_tn2, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF_TN2 -DFRAG_ID=any");

#send echo request from tn2 to nut(off link)
vClear($IF);
vSend($IF, 'echo_request1500_tn2');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn2',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	$packet_len = 0;
	$fragment_id = 0;
	$PTB_payload = '_PACKET_IPV6_echo_reply1500_tn2';
	if($ret{'recvFrame'} eq 'echo_reply1500_tn2'){
		vLogHTML('OK<BR>');
		$packet_len = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$PTB_payload = "_PACKET_IPV6_$pkt_name";
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";

		#get ipv6 packet length
		$packet_len = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;
		#get id
		$fragment_id = $ret{"Frame_Ether.Packet_IPv6.Hdr_Fragment.Identification"};	
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			#get ipv6 packet length
			$packet_len_2nd = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;	
			if($packet_len < $packet_len_2nd){
				$PTB_payload = "_PACKET_IPV6_$name_2nd_frag";
				$packet_len = $packet_len_2nd;
				#get id
				$fragment_id = $ret{"Frame_Ether.Packet_IPv6.Hdr_Fragment.Identification"};
			}
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
		
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}

keep_cache_tn1_and_tr1($IF);



#----- create fragment pkt.def(from tn3 to nut)

$original_name = "echo_reply1500_tn3"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN3_GL3_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn3 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn3');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn3',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	if($ret{'recvFrame'} eq 'echo_reply1500_tn3'){
		vLogHTML('OK<BR>');
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
		
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}


keep_cache_tn1_and_tr1($IF);
unlink($def_file);



#send Packet Too Big to NUT for echo reply to TN2
if($packet_len > 1280){
	if($packet_len >= 1400){
		vCPP("-DFRAG_DEF_TN2 -DMAX_MTU=1400 -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id");
		vSend($IF, 'PktTooBig1400_tn2');
		$max_mtu = 1400;
	}
	else{
		vCPP("-DFRAG_DEF_TN2 -DMAX_MTU=$packet_len -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id");
		vSend($IF, 'PktTooBig1400_tn2');
		$max_mtu = packet_len;
	}
}else{
	$max_mtu = 1280;
	vLogHTML('<FONT COLOR="#FF0000">Cannot send Packet Too Big message</FONT><BR>');
}


unlink($def_file_tn2);




#----- create fragment pkt.def(from tn1 to nut(onlink))

$original_name = "echo_reply1500_tn1"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_hether_nut_to_onlinkTN1';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN1_GL0_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF  -DFRAG_ID=any");


#send echo request from tn1 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn1');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn1',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	if($ret{'recvFrame'} eq 'echo_reply1500_tn1'){
		vLogHTML('OK<BR>');
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
	
	
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);

#----- create fragment pkt.def(from tn2 to nut)

$original_name = "echo_reply1500_tn2"; #must same echo reply packet
$MTU_value = $max_mtu ; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN2_GL2_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn2 to nut(off link)
vClear($IF);
vSend($IF, 'echo_request1500_tn2');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, @CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	vLogHTML('OK. recive 1st fragment.<BR>');
	$pkt_name = $ret{'recvFrame'};
	$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
	$size_2nd_frag = $1-$2-40;
	$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
	%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
	if ($ret{'status'} == 0) {
		vLogHTML('OK. recive 2nd fragment.<BR>');
	
	}else {
		vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
		$endStatus = $V6evalTool::exitFail;
	}

		
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);



#----- create fragment pkt.def(from tn3 to nut)

$original_name = "echo_reply1500_tn3"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN3_GL3_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn3 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn3');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn3',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	$packet_len = 0;
	$fragment_id = 0;
	$PTB_payload = '_PACKET_IPV6_echo_reply1500_tn3';
	if($ret{'recvFrame'} eq 'echo_reply1500_tn3'){
		vLogHTML('OK<BR>');
		$packet_len = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$PTB_payload = "_PACKET_IPV6_$pkt_name";
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
		#get ipv6 packet length
		$packet_len = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;		
        #get id
		$fragment_id = $ret{"Frame_Ether.Packet_IPv6.Hdr_Fragment.Identification"};
		
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			#get ipv6 packet length
			$packet_len_2nd = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40;	
			if($packet_len < $packet_len_2nd){
				$PTB_payload = "_PACKET_IPV6_$name_2nd_frag";
				$packet_len = $packet_len_2nd;
				#get id
				$fragment_id = $ret{"Frame_Ether.Packet_IPv6.Hdr_Fragment.Identification"};
			}
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
		
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}

keep_cache_tn1_and_tr1($IF);



#send Packet Too Big to NUT for echo reply to TN3
if($packet_len > 1280){
		vCPP("-DFRAG_DEF -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id");
		vSend($IF, 'PktTooBig1280_tn3');
}else{
	vLogHTML('<FONT COLOR="#FF0000">Cannot send Packet Too Big message</FONT><BR>');
}


unlink($def_file);



#----- create fragment pkt.def(from tn1 to nut(onlink))

$original_name = "echo_reply1500_tn1"; #must same echo reply packet
$MTU_value = 1500; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_hether_nut_to_onlinkTN1';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN1_GL0_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn1 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn1');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply1500_tn1',@CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	if($ret{'recvFrame'} eq 'echo_reply1500_tn1'){
		vLogHTML('OK<BR>');
	}
	else{
		vLogHTML('OK. recive 1st fragment.<BR>');
		$pkt_name = $ret{'recvFrame'};
		$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
		$size_2nd_frag = $1-$2-40;
		$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
		%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
		if ($ret{'status'} == 0) {
			vLogHTML('OK. recive 2nd fragment.<BR>');
			
		}
		else {
			vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
			$endStatus = $V6evalTool::exitFail;
		}
	}
	
	
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);

#----- create fragment pkt.def(from tn2 to nut)

$original_name = "echo_reply1500_tn2"; #must same echo reply packet
$MTU_value = $max_mtu ; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN2_GL2_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn2 to nut(off link)
vClear($IF);
vSend($IF, 'echo_request1500_tn2');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, @CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	vLogHTML('OK. recive 1st fragment.<BR>');
	$pkt_name = $ret{'recvFrame'};
	$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
	$size_2nd_frag = $1-$2-40;
	$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
		
	%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
	if ($ret{'status'} == 0) {
		vLogHTML('OK. recive 2nd fragment.<BR>');
	
	}else {
		vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
		$endStatus = $V6evalTool::exitFail;
	}

		
}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);



#----- create fragment pkt.def(from tn3 to nut)

$original_name = "echo_reply1500_tn3"; #must same echo reply packet
$MTU_value = 1280; #MTU value, fixed
$PKT_size = 1500; #this size is IPv6 pakcet size.,1280,1400,1500 etc

$frag_start =  48; #1280 or 48 #should be 48

$data_size_1st = $frag_start - 40 - 8;
$data_size_2nd = ($PKT_size - 40) - $data_size_1st;

#define packet format
$header_ether = '_HETHER_nut2tn';
$ip_src = 'NUT_GL0_ADDR';
$ip_dst = 'TN3_GL3_ADDR';

$def_file = 'pkt_frag.def'; #fragment define file

#write def file
if(writefragdef($def_file, $original_name, $MTU_value,$PKT_size,$data_size_1st,$data_size_2nd, $header_ether, $ip_src, $ip_dst ) != $CommonPMTU::Success) {
	exit($V6evalTool::exitFatal);
}
vCPP("-DFRAG_DEF -DFRAG_ID=any");


#send echo request from tn3 to nut(on link)
vClear($IF);
vSend($IF, 'echo_request1500_tn3');
%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, @CommonPMTU::fragment_1st_name);

if ($ret{'status'} == 0) {
	vLogHTML('OK. recive 1st fragment.<BR>');
	$pkt_name = $ret{'recvFrame'};
	$pkt_name =~ /^echo_reply(\d+)_1st_(\d+)$/;
	$size_2nd_frag = $1-$2-40;
	$name_2nd_frag = "echo_reply$1"."_2nd_$size_2nd_frag";
	
	%ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, "$name_2nd_frag");
	if ($ret{'status'} == 0) {
		vLogHTML('OK. recive 2nd fragment.<BR>');
		
	}
	else {
		vLogHTML('<FONT COLOR="#FF0000">NG. can\'t recive 2nd fragment.</FONT><BR>');
		$endStatus = $V6evalTool::exitFail;
	}

}else {
	vLogHTML('Cannot receive Echo Reply<BR>');
	vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
	$endStatus = $V6evalTool::exitFail;
}
keep_cache_tn1_and_tr1($IF);
unlink($def_file);



#----- end test
additional_cleanup($IF);
$ret = cleanup($IF);

vStop($IF);
if ($ret == $CommonPMTU::Success) {
	exit($endStatus);
} else {
	exit($V6evalTool::exitFatal);
}

sub additional_setup {
	my($IF) = @_;
	my(%ret, $status);

	vLogHTML('--- start additional Setup<BR>');

	vSend($IF, 'setup_echo_request_tn1');
	%ret = vRecv($IF, $CommonPMTU::wait_reply, 0, 0, 'setup_echo_reply_tn1', 'ns_g2g_tn1', 'ns_l2g_tn1');
	if ($ret{'status'} == 0) {
		if ($ret{'recvFrame'} eq 'ns_g2g_tn1') {
			vSend($IF, 'na_g2g_tn1');
			%ret = vRecv($IF, $CommonPMTU::wait_reply, 0, 0, 'setup_echo_reply_tn1');
		} elsif ($ret{'recvFrame'} eq 'ns_l2g_tn1') {
			vSend($IF, 'na_g2l_tn1');
			%ret = vRecv($IF, $CommonPMTU::wait_reply, 0, 0, 'setup_echo_reply_tn1');
		}
	}
	if ($ret{'status'} == 0 and $ret{'recvFrame'} eq 'setup_echo_reply_tn1') {
		vLogHTML('OK<BR>');
		$status = $CommonPMTU::Success;
	} else {
		vLogHTML('Cannot receive Echo Reply<BR>');
		vLogHTML('<FONT COLOR="#FF0000">NG</FONT><BR>');
		vLogHTML('<FONT COLOR="#FF0000">setup failure</FONT><BR>');
		$status = $CommonPMTU::Failure;
	}

	vClear($IF);
	vLogHTML('--- end additional Setup<BR>');

	return ($status);
}


sub additional_cleanup {
	vLogHTML('--- additional Cleanup NUT<BR>');

	if ($CommonPMTU::cleanup eq 'normal') {
		vSend($IF, 'cleanup_na_tn1');
		vSend($IF, 'cleanup_echo_request_tn1');
		vLogHTML("Wait for transit target Neighbor Cache Entry to INCOMPLETE/NONCE ($CommonPMTU::wait_incomplete sec.)<BR>");
		vRecv($IF, $CommonPMTU::wait_incomplete, 0, 0);
	}
}



sub
keep_cache_tn1_and_tr1($) {
	my ($link) = @_;

	my $true	= 1;
	my $false	= 0;

	my $delay_first_probe_time = 5;

	$pktdesc{'ucast_ns_tn1_from_linklocal_sll'}
			= 'Recv NS w/ SLL: NUT (link-local) -&gt; TN1 (global)';

	$pktdesc{'ucast_ns_tn1_from_linklocal'}
			= 'Recv NS: NUT (link-local) -&gt; TN1 (global)';

	$pktdesc{'ucast_ns_tn1_from_global_sll'}
		= 'Recv NS w/ SLL: NUT (global) -&gt; TN1 (global)';

	$pktdesc{'ucast_ns_tn1_from_global'}
		= 'Recv NS: NUT (global) -&gt; TN1 (global)';


	$pktdesc{'ucast_na_tn1_to_linklocal'}
		= 'Send NA: TN1 (global) -&gt; NUT (link-local)';

	$pktdesc{'ucast_na_tn1_to_global'}
		= 'Send NA: TN1 (global) -&gt; NUT (global)';


	$pktdesc{'ucast_ns_tr1_from_linklocal_sll'}
		= 'Recv NS w/ SLL: NUT (link-local) -&gt; TR1 (link-local)';

	$pktdesc{'ucast_ns_tr1_from_linklocal'}
		= 'Recv NS: NUT (link-local) -&gt; TR1 (link-local)';

	$pktdesc{'ucast_ns_tr1_from_global_sll'}
		= 'Recv NS w/ SLL: NUT (global) -&gt; TR1 (link-local)';

	$pktdesc{'ucast_ns_tr1_from_global'}
		= 'Recv NS: NUT (global) -&gt; TR1 (link-local)';


	$pktdesc{'ucast_na_tr1_to_linklocal'}
		= 'Send NA: TR1 (link-local) -&gt; NUT (link-local)';

	$pktdesc{'ucast_na_tr1_to_global'}
		= 'Send NA: TR1 (link-local) -&gt; NUT (global)';

	my %magic_tn1 = (
		'ucast_ns_tn1_from_linklocal_sll'
			=> 'ucast_na_tn1_to_linklocal',

		'ucast_ns_tn1_from_linklocal'
			=> 'ucast_na_tn1_to_linklocal',

		'ucast_ns_tn1_from_global_sll'
			=> 'ucast_na_tn1_to_global',

		'ucast_ns_tn1_from_global'
			=> 'ucast_na_tn1_to_global',
	);

	my %magic_tr1 = (
		'ucast_ns_tr1_from_linklocal_sll'
			=> 'ucast_na_tr1_to_linklocal',

		'ucast_ns_tr1_from_linklocal'
			=> 'ucast_na_tr1_to_linklocal',

		'ucast_ns_tr1_from_global_sll'
			=> 'ucast_na_tr1_to_global',

		'ucast_ns_tr1_from_global'
			=> 'ucast_na_tr1_to_global'
	);

 	vLogHTML('===&gt; '.
 		'make it sure to keep neighbor cache for TN1&amp;TR1'.
 		' &lt;===<BR>');

	vLogHTML('&gt;&gt;&gt;&gt; '.
		'TN1|TR1: REACHABLE|STALE|DELAY &gt;&gt;&gt;&gt;<BR>');

	# TN1&TR1: REACHABLE/STALE/DELAY
	my %ret = vRecv($link, $delay_first_probe_time + 1, 0, 0,
		keys(%magic_tn1), keys(%magic_tr1));

	my $bool_tn1	= $false;
	my $bool_tr1	= $false;

	for( ; ; ) {
		foreach my $frame (keys(%magic_tn1)) {
			if($ret{'recvFrame'} eq $frame) {
				$bool_tn1 = $true;
				last;
			}
		}

		if($bool_tn1) {
			last;
		}

		foreach my $frame (keys(%magic_tr1)) {
			if($ret{'recvFrame'} eq $frame) {
				$bool_tr1 = $true;
				last;
			}
		}

		if($bool_tr1) {
			last;
		}


		last;
	}

	for( ; ; ) {
		if($bool_tn1) {
			# TN1: PROBE
			vSend($link, $magic_tn1{$ret{'recvFrame'}});
			# TN1: REACHABLE

			%ret = vRecv($link, $delay_first_probe_time + 1, 0, 0,
				keys(%magic_tr1));

			foreach my $frame (keys(%magic_tr1)) {
				if($ret{'recvFrame'} eq $frame) {
					$bool_tr1 = $true;
					last;
				}
			}

			if($bool_tr1) {
				# TR1: PROBE
				vSend($link, $magic_tr1{$ret{'recvFrame'}});
				# TR1: REACHABLE
			}

			last;
		}

		if($bool_tr1) {
			# TR1: PROBE
			vSend($link, $magic_tr1{$ret{'recvFrame'}});
			# TR1: REACHABLE

			%ret = vRecv($link, $delay_first_probe_time + 1, 0, 0,
				keys(%magic_tn1));

			foreach my $frame (keys(%magic_tn1)) {
				if($ret{'recvFrame'} eq $frame) {
					$bool_tn1 = $true;
					last;
				}
			}

			if($bool_tn1) {
				# TN1: PROBE
				vSend($link, $magic_tn1{$ret{'recvFrame'}});
				# TN1: REACHABLE
			}

			last;
		}

		last;
	}

	# TN1&TR1: REACHABLE|STALE

	vLogHTML('&lt;&lt;&lt;&lt; '.
		'TN1&amp;TR1: REACHABLE|STALE &lt;&lt;&lt;&lt;<BR>');

	return;
}



######################################################################
__END__

=head1 NAME

  storedPMTU - Verify that a node can store Path MTU information for multiple destinations

=head1 TARGET

  Host and Router

=head1 SYNOPSIS

=begin html
<PRE>
  <A HREF="./storedPMTU.seq">storedPMTU.seq</A> [-tooloption ...] -pkt <A HREF="./storedPMTU.def">storedPMTU.def</A>
    -tooloption : v6eval tool option
</PRE>

=end html

=head1 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.

=head1 TEST PROCEDURE

   TN3                    TN2                    TR1                    NUT                    TN1
    |                      |                      |                      |                      |
    |                      |                      |                      |<---------------------|
    |                      |                      |                      |   1.Echo Request     |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      |                      |                      +--------------------->|
    |                      |                      |                      |   2.Echo Reply       |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      +-------------------------------------------->|                      |
    |                      |  3.Echo Request      |                      |                      |
    |                      |  (1500 octets)       |                      |                      |
    |                      |                      |                      |                      |
    |                      |<--------------------------------------------+                      |
    |                      |  4.Echo Reply        |                      |                      |
    |                      |  (1500 octets)       |                      |                      |
    |                      |                      |                      |                      |
    +----------------------|-------------------------------------------->|                      |
    |   5.Echo Request     |                      |                      |                      |
    |   (1500 octets)      |                      |                      |                      |
    |                      |                      |                      |                      |
    |<---------------------|---------------------------------------------+                      |
    |   6.Echo Reply       |                      |                      |                      |
    |   (1500 octets)      |                      |                      |                      |
    |                      |                      |                      |                      |
    |                      |                      +--------------------->|                      |
    |                      |                      |  7.Packet Too Big    |                      |
    |                      |                      |  for TN2 (MTU 1400)  |                      |
    |                      |                      |                      |                      |
    |                      |                      |                      |<---------------------|
    |                      |                      |                      |   8.Echo Request     |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      |                      |                      +--------------------->|
    |                      |                      |                      |   9.Echo Reply       |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      +-------------------------------------------->|                      |
    |                      | 10.Echo Request      |                      |                      |
    |                      |  (1500 octets)       |                      |                      |
    |                      |                      |                      |                      |
    |                      |<--------------------------------------------+                      |
    |                      |11.Fragment Echo Reply|                      |                      |
    |                      |  (1st + 2nd =1500)   |                      |                      |
    |                      |                      |                      |                      |
    +----------------------|-------------------------------------------->|                      |
    |  12.Echo Request     |                      |                      |                      |
    |   (1500 octets)      |                      |                      |                      |
    |                      |                      |                      |                      |
    |<---------------------|---------------------------------------------+                      |
    |  13.Echo Reply       |                      |                      |                      |
    |   (1500 octets)      |                      |                      |                      |
    |                      |                      |                      |                      |
    |                      |                      +--------------------->|                      |
    |                      |                      | 14.Packet Too Big    |                      |
    |                      |                      |  for TN3 (MTU 1280)  |                      |
    |                      |                      |                      |                      |
    |                      |                      |                      |<---------------------|
    |                      |                      |                      |  15.Echo Request     |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      |                      |                      +--------------------->|
    |                      |                      |                      |  16.Echo Reply       |
    |                      |                      |                      |   (1500 octets)      |
    |                      |                      |                      |                      |
    |                      +-------------------------------------------->|                      |
    |                      | 17.Echo Request      |                      |                      |
    |                      |  (1500 octets)       |                      |                      |
    |                      |                      |                      |                      |
    |                      |<--------------------------------------------+                      |
    |                      |18.Fragment Echo Reply|                      |                      |
    |                      |  (1st + 2nd = 1500)  |                      |                      |
    |                      |                      |                      |                      |
    +----------------------|-------------------------------------------->|                      |
    |  19.Echo Request     |                      |                      |                      |
    |   (1500 octets)      |                      |                      |                      |
    |                      |                      |                      |                      |
    |<---------------------|---------------------------------------------+                      |
    |20.Fragment Echo Reply|                      |                      |                      |
    |   (1st + 2nd = 1500) |                      |                      |                      |
    |                      |                      |                      |                      |
    v                      v                      v                      v                      v

  1. Send Echo Request from TN1
  2. Receive Echo Reply to TN1 <<Check 1>>
  3. Send Echo Request from TN2
  4. Receive Echo Reply to TN2 <<Check 2>>
  5. Send Echo Request from TN3
  6. Receive Echo Reply to TN3 <<Check 3>>
  7. Send Packet Too Big message from TR1 for Echo Reply to TN2
  8. Send Echo Request from TN1
  9. Receive Echo Reply to TN1 <<Check 4>>
 10. Send Echo Request from TN2
 11. Receive fragmented Echo Reply to TN2 <<Check 5>>
 12. Send Echo Request from TN3
 13. Receive Echo Reply to TN3 <<Check 6>>
 14. Send Packet Too Big message from TR1 for Echo Reply to TN3
 15. Send Echo Request from TN1
 16. Receive Echo Reply to TN1 <<Check 7>>
 17. Send Echo Request from TN2
 18. Receive fragmented Echo Reply to TN2 <<Check 8>>
 19. Send Echo Request from TN3
 20. Receive fragmented Echo Reply to TN3 <<Check 9>>

  Echo Request Data is:

        IPv6 Header
            Version            = 6
            Traffic Class      = 0
            FlowLabel          = 0
            PayloadLength      = 1460
            NextHeader         = 58 (ICMPv6)
            SourceAddress      = TN1,TN2 or TN3's Global Address
            DestinationAddress = NUT's Global Address

        ICMP Echo Request
            Type           = 128 (Echo Request)
            Code           = 0
            Checksum       = (auto)
            Identifier     = 0xffff
            SequenceNumber = 1
            PayloadData    = (PayloadLength - 8 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            = 1400 or 1280
            PayloadData    = (1232 octets)

=head1 JUDGEMENT

  PASS: <<Check 1,2,3,4,6,7>> Echo Reply or Fragment Echo Reply Received
        <<Check 5,8>> Fragment Echo Reply Received. 1st and 2nd fragment no larger than 1400 octets.
        <<Check 9>> Fragment Echo Reply Received. 1st and 2nd fragment no larger than 1280 octets.

        IPv6 Header
            Version             = 6
            Traffic Class       = 0
            FlowLabel           = 0
            PayloadLength      = 1460
            NextHeader          = 58 (ICMPv6)
            SourceAddress       = NUT's Global Address
            Destination Address = TN1,TN2 or TN3'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    = (PayloadLength - 8 octets) (same as Echo Request)




=cut

# =head1 REFERENCE
# 
# RFC1981
# 
# 5.2. Storing PMTU information
# 
#    Ideally, a PMTU value should be associated with a specific path
#    traversed by packets exchanged between the source and destination
#    nodes.  However, in most cases a node will not have enough
#    information to completely and accurately identify such a path.
#    Rather, a node must associate a PMTU value with some local
#    representation of a path.  It is left to the implementation to select
#    the local representation of a path.
# 
#    In the case of a multicast destination address, copies of a packet
#    may traverse many different paths to reach many different nodes.  The
#    local representation of the "path" to a multicast destination must in
#    fact represent a potentially large set of paths.
# 
#    Minimally, an implementation could maintain a single PMTU value to be
#    used for all packets originated from the node.  This PMTU value would
#    be the minimum PMTU learned across the set of all paths in use by the
#    node.  This approach is likely to result in the use of smaller
#    packets than is necessary for many paths.
# 
#    An implementation could use the destination address as the local
#    representation of a path.  The PMTU value associated with a
#    destination would be the minimum PMTU learned across the set of all
#    paths in use to that destination.  The set of paths in use to a
#    particular destination is expected to be small, in many cases
#    consisting of a single path.  This approach will result in the use of
#    optimally sized packets on a per-destination basis.  This approach
#    integrates nicely with the conceptual model of a host as described in
#    [ND]: a PMTU value could be stored with the corresponding entry in
#    the destination cache.
# 
#    If flows [IPv6-SPEC] are in use, an implementation could use the flow
#    id as the local representation of a path.  Packets sent to a
#    particular destination but belonging to different flows may use
#    different paths, with the choice of path depending on the flow id.
#    This approach will result in the use of optimally sized packets on a
#    per-flow basis, providing finer granularity than PMTU values
#    maintained on a per-destination basis.
# 
#    For source routed packets (i.e. packets containing an IPv6 Routing
#    header [IPv6-SPEC]), the source route may further qualify the local
#    representation of a path.  In particular, a packet containing a type
#    0 Routing header in which all bits in the Strict/Loose Bit Map are
#    equal to 1 contains a complete path specification.  An implementation
#    could use source route information in the local representation of a
#    path.
# 
#       Note: Some paths may be further distinguished by different
#       security classifications.  The details of such classifications are
#       beyond the scope of this memo.
# 
#    Initially, the PMTU value for a path is assumed to be the (known) MTU
#    of the first-hop link.
# 
#    When a Packet Too Big message is received, the node determines which
#    Big message.  For example, if the destination address is used as the
#    local representation of a path, the destination address from the
#    original packet would be used to determine which path the message
#    applies to.
# 
#       Note: if the original packet contained a Routing header, the
#       Routing header should be used to determine the location of the
#       destination address within the original packet.  If Segments Left
#       is equal to zero, the destination address is in the Destination
#       Address field in the IPv6 header.  If Segments Left is greater
#       than zero, the destination address is the last address
#       (Address[n]) in the Routing header.
# 
#    The node then uses the value in the MTU field in the Packet Too Big
#    message as a tentative PMTU value, and compares the tentative PMTU to
#    the existing PMTU.  If the tentative PMTU is less than the existing
#    PMTU estimate, the tentative PMTU replaces the existing PMTU as the
#    PMTU value for the path.
# 
#    The packetization layers must be notified about decreases in the
#    PMTU.  Any packetization layer instance (for example, a TCP
#    connection) that is actively using the path must be notified if the
#    PMTU estimate is decreased.
# 
#       Note: even if the Packet Too Big message contains an Original
#       Packet Header that refers to a UDP packet, the TCP layer must be
#       notified if any of its connections use the given path.
# 
#    Also, the instance that sent the packet that elicited the Packet Too
#    Big message should be notified that its packet has been dropped, even
#    if the PMTU estimate has not changed, so that it may retransmit the
#    dropped data.
# 
#       Note: An implementation can avoid the use of an asynchronous
#       notification mechanism for PMTU decreases by postponing
#       notification until the next attempt to send a packet larger than
#       the PMTU estimate.  In this approach, when an attempt is made to
#       SEND a packet that is larger than the PMTU estimate, the SEND
#       function should fail and return a suitable error indication.  This
#       approach may be more suitable to a connectionless packetization
#       layer (such as one using UDP), which (in some implementations) may
#       be hard to "notify" from the ICMP layer.  In this case, the normal
#       timeout-based retransmission mechanisms would be used to recover
#       from the dropped packets.
# 
#    It is important to understand that the notification of the
#    packetization layer instances using the path about the change in the
#    PMTU is distinct from the notification of a specific instance that a
#    packet has been dropped.  The latter should be done as soon as
#    packetization layer instance), while the former may be delayed until
#    a packetization layer instance wants to create a packet.
#    Retransmission should be done for only for those packets that are
#    known to be dropped, as indicated by a Packet Too Big message.
# 
# 

=pod

=head1 REFERENCE

=begin html
<BLOCKQUOTE>
<PRE>
RFC 1981 - Path MTU Discovery for IPv6
</PRE>
</BLOCKQUOTE>

=end html

=head1 SEE ALSO

  perldoc V6evalTool

=cut