#!/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: reducePMTUofflink.seq,v 1.5 2005/04/11 09:05:56 akisada Exp $ # ###################################################################### BEGIN { $V6evalTool::TestVersion = '$Name: V6LC_P2_1_4_6 $'; } use V6evalTool; use CommonPMTU; $pktdesc{'echo_request_pl1400'} = 'Send Echo Request (Payload Length is 1400)'; $pktdesc{'echo_reply_pl1400'} = 'Recv Echo Reply (Payload Length is 1400)'; $pktdesc{'PktTooBig1400'} = 'Send Packet Too Big message'; $pktdesc{'echo_request1500'} = 'Send Echo Request (Packet size is 1500)'; $pktdesc{'PktTooBig1280'} = 'Send Packet Too Big message (1280 octets)'; $endStatus = $V6evalTool::exitPass; $IF = 'Link0'; #fake data $fragment_id = 0; $PTB_payload = '_PACKET_IPV6_echo_reply_pl1400'; $packet_len = 1500; vCapture($IF); #====================================================================== if (setup11($IF) != $CommonPMTU::Success) { $ret = cleanup($IF); if ($ret == $CommonPMTU::Success) { exit($V6evalTool::exitFail); } else { exit($V6evalTool::exitFatal); } } #====================================================================== #----- test #----- create fragment pkt.def(from tn2 to nut(onlink)) $original_name = "echo_reply_pl1400"; #must same echo reply packet $MTU_value = 1500; #MTU value, fixed $PKT_size = 1440; #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"); #packet send vSend($IF, 'echo_request_pl1400'); %ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, 'echo_reply_pl1400',@CommonPMTU::fragment_1st_name); if ($ret{'status'} == 0) { $packet_len = 0; $fragment_id = 0; $PTB_payload = '_PACKET_IPV6_echo_reply_pl1400'; if($ret{'recvFrame'} eq 'echo_reply_pl1400'){ vLogHTML('OK
'); $packet_len = $ret{"Frame_Ether.Packet_IPv6.Hdr_IPv6.PayloadLength"} + 40; } else{ vLogHTML('OK. recive 1st fragment.
'); $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.
'); #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('NG. can\'t recive 2nd fragment.
'); $endStatus = $V6evalTool::exitFail; } } }else { vLogHTML('Cannot receive Echo Reply
'); vLogHTML('NG
'); $endStatus = $V6evalTool::exitFail; } #send Packet Too Big to NUT for echo reply to TN2 if($packet_len > 1280){ if($packet_len >= 1400){ vCPP("-DFRAG_DEF -DMAX_MTU=1400 -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id"); vSend($IF, 'PktTooBig1400'); $max_mtu = 1400; } else{ vCPP("-DFRAG_DEF -DMAX_MTU=$packet_len -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id"); vSend($IF, 'PktTooBig1400'); $max_mtu = packet_len; } }else{ $max_mtu = 1280; vLogHTML('Cannot send Packet Too Big message
'); } unlink($def_file); #----- create fragment pkt.def(from tn2 to nut) $original_name = "echo_reply1500"; #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) vSend($IF, 'echo_request1500'); %ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, @CommonPMTU::fragment_1st_name); if ($ret{'status'} == 0) { $packet_len = 0; $fragment_id = 0; vLogHTML('OK. recive 1st fragment.
'); $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.
'); #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('NG. can\'t recive 2nd fragment.
'); $endStatus = $V6evalTool::exitFail; } }else { vLogHTML('Cannot receive Echo Reply
'); vLogHTML('NG
'); $endStatus = $V6evalTool::exitFail; } #send Packet Too Big to NUT for echo reply to TN2 if($packet_len > 1280){ vCPP("-DFRAG_DEF -DPAYLOAD=$PTB_payload -DFRAG_ID=$fragment_id"); vSend($IF, 'PktTooBig1280'); }else{ vLogHTML('Cannot send Packet Too Big message
'); } unlink($def_file); #----- create fragment pkt.def(from tn2 to nut) $original_name = "echo_reply1500"; #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 = '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) vSend($IF, 'echo_request1500'); %ret = nd_vRecv_EN($IF, $CommonPMTU::wait_reply, 0, 0, @CommonPMTU::fragment_1st_name); if ($ret{'status'} == 0) { vLogHTML('OK. recive 1st fragment.
'); $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.
'); }else { vLogHTML('NG. can\'t recive 2nd fragment.
'); $endStatus = $V6evalTool::exitFail; } }else { vLogHTML('Cannot receive Echo Reply
'); vLogHTML('NG
'); $endStatus = $V6evalTool::exitFail; } unlink($def_file); #----- end test $ret = cleanup($IF); vStop($IF); if ($ret == $CommonPMTU::Success) { exit($endStatus); } else { exit($V6evalTool::exitFatal); } ###################################################################### __END__ =head1 NAME reducePMTUofflink - Verify that a node properly reduces its estimate of the MTU for a path due to a Packet Too Big message indicating a reduction in Path MTU for a global destination =head1 TARGET Host and Router =head1 SYNOPSIS =begin html 
  reducePMTUofflink.seq [-tooloption ...] -pkt reducePMTUofflink.def
    -tooloption : v6eval tool option
=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 TN2 TR1 NUT | | | |-------------------------------------------->| | 1.Echo Request | | | (1440 octets) | | | | | |<--------------------------------------------| | 2.Echo Reply | | | (1440 octets) | | | | | | +--------------------->| | | 3.Packet Too Big | | | (MTU 1400) | | | | |-------------------------------------------->| | 4.Echo Request | | | (1500 octets) | | | | | |<--------------------------------------------| | 5.Fragment Echo Reply| | | (1st + 2nd = 1500) | | | | | | +--------------------->| | | 6.Packet Too Big | | | (MTU 1280) | | | | |-------------------------------------------->| | 7.Echo Request | | | (1500 octets) | | | | | |<--------------------------------------------| | 8.Fragment Echo Reply| | | (1st + 2nd = 1500) | | | | | v v v 1. Send Echo Request (Payload Length is 1400) 2. Receive Echo Reply (Payload Length is 1400)<> 3. Send Packet Too Big message (MTU is 1400) 4. Send Echo Request (Packet size is 1500) 5. Receive fragmented Echo Reply (1st + 2nd Fragment size is 1500)<> 6. Send Packet Too Big message (MTU is 1280) 7. Send Echo Request (Packet size is 1500) 8. Receive fragmented Echo Reply (1st + 2nd Fragment size is 1500)<> Echo Request Data is: IPv6 Header Version = 6 Traffic Class = 0 FlowLabel = 0 PayloadLength = 1400 or 1460 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 = (1392 or 1452 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 = 1400,1280 PayloadData = (1232 octets) =head1 JUDGEMENT PASS: <> Echo Reply Received or Fragment Echo Reply Received <> Fragment Echo Reply Received. 1st and 2nd fragment no larger than 1400 octets. <> Fragment Echo Reply Received. 1st and 2nd fragment no larger than 1280 octets. IPv6 Header Version = 6 Traffic Class = 0 FlowLabel = 0 PayloadLength = 1400,1460 NextHeader = 58 (ICMPv6) SourceAddress = NUT's 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 = (1392 or 1452 octets ) (same as Echo Request) =cut # =head1 REFERENCE # # RFC1981 # # 4. Protocol Requirements # # As discussed in section 1, IPv6 nodes are not required to implement # Path MTU Discovery. The requirements in this section apply only to # those implementations that include Path MTU Discovery. # # When a node receives a Packet Too Big message, it MUST reduce its # estimate of the PMTU for the relevant path, based on the value of the # MTU field in the message. The precise behavior of a node in this # circumstance is not specified, since different applications may have # different requirements, and since different implementation # architectures may favor different strategies. # # After receiving a Packet Too Big message, a node MUST attempt to # avoid eliciting more such messages in the near future. The node MUST # reduce the size of the packets it is sending along the path. Using a # PMTU estimate larger than the IPv6 minimum link MTU may continue to # elicit Packet Too Big messages. Since each of these messages (and # the dropped packets they respond to) consume network resources, the # node MUST force the Path MTU Discovery process to end. # # Nodes using Path MTU Discovery MUST detect decreases in PMTU as fast # as possible. Nodes MAY detect increases in PMTU, but because doing # so requires sending packets larger than the current estimated PMTU, # and because the likelihood is that the PMTU will not have increased, # this MUST be done at infrequent intervals. An attempt to detect an # increase (by sending a packet larger than the current estimate) MUST # NOT be done less than 5 minutes after a Packet Too Big message has # been received for the given path. The recommended setting for this # timer is twice its minimum value (10 minutes). # # A node MUST NOT reduce its estimate of the Path MTU below the IPv6 # minimum link MTU. # # Note: A node may receive a Packet Too Big message reporting a # next-hop MTU that is less than the IPv6 minimum link MTU. In that # case, the node is not required to reduce the size of subsequent # packets sent on the path to less than the IPv6 minimun link MTU, # but rather must include a Fragment header in those packets [IPv6- # SPEC]. # # A node MUST NOT increase its estimate of the Path MTU in response to # the contents of a Packet Too Big message. A message purporting to # announce an increase in the Path MTU might be a stale packet that has # been floating around in the network, a false packet injected as part # of a denial-of-service attack, or the result of having multiple paths # to the destination, each with a different PMTU. # # # (omit) # # 5.1. Layering # # In the IP architecture, the choice of what size packet to send is # made by a protocol at a layer above IP. This memo refers to such a # protocol as a "packetization protocol". Packetization protocols are # usually transport protocols (for example, TCP) but can also be # higher-layer protocols (for example, protocols built on top of UDP). # # # Implementing Path MTU Discovery in the packetization layers # simplifies some of the inter-layer issues, but has several drawbacks: # the implementation may have to be redone for each packetization # protocol, it becomes hard to share PMTU information between different # packetization layers, and the connection-oriented state maintained by # some packetization layers may not easily extend to save PMTU # information for long periods. # # It is therefore suggested that the IP layer store PMTU information # and that the ICMP layer process received Packet Too Big messages. # The packetization layers may respond to changes in the PMTU, by # changing the size of the messages they send. To support this # layering, packetization layers require a way to learn of changes in # the value of MMS_S, the "maximum send transport-message size". The # MMS_S is derived from the Path MTU by subtracting the size of the # IPv6 header plus space reserved by the IP layer for additional # headers (if any). # # It is possible that a packetization layer, perhaps a UDP application # outside the kernel, is unable to change the size of messages it # sends. This may result in a packet size that exceeds the Path MTU. # To accommodate such situations, IPv6 defines a mechanism that allows # large payloads to be divided into fragments, with each fragment sent # in a separate packet (see [IPv6-SPEC] section "Fragment Header"). # However, packetization layers are encouraged to avoid sending # messages that will require fragmentation (for the case against # fragmentation, see [FRAG]). # # # =pod =head1 REFERENCE =begin html 
RFC 1981 - Path MTU Discovery for IPv6
=end html =head1 SEE ALSO perldoc V6evalTool =cut