EP1491004A1 - Procede de recherche de mtu a chemin de transmission dans un reseau ip et appareil correspondant - Google Patents

Procede de recherche de mtu a chemin de transmission dans un reseau ip et appareil correspondant

Info

Publication number
EP1491004A1
EP1491004A1 EP03745468A EP03745468A EP1491004A1 EP 1491004 A1 EP1491004 A1 EP 1491004A1 EP 03745468 A EP03745468 A EP 03745468A EP 03745468 A EP03745468 A EP 03745468A EP 1491004 A1 EP1491004 A1 EP 1491004A1
Authority
EP
European Patent Office
Prior art keywords
message
packet
mtu
icmp
information
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP03745468A
Other languages
German (de)
English (en)
Inventor
Hak-Goo 4-208 Limkwang Apt. LEE
Young-Keun 528-103 Daedong Apt. KIM
Sun-Woo 331-1602 Gwonseon 3-Jigu KIM
Yong-Jun Lim
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Samsung Electronics Co Ltd
Original Assignee
Samsung Electronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR10-2002-0034131A external-priority patent/KR100453055B1/ko
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Publication of EP1491004A1 publication Critical patent/EP1491004A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H04L69/166—IP fragmentation; TCP segmentation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H04L69/167—Adaptation for transition between two IP versions, e.g. between IPv4 and IPv6

Definitions

  • the present invention relates to a method and apparatus for more efficiently operating a network, and more particularly, to a method and apparatus for more efficiently performing discovery of a maximum transmission unit (MTU) on a path of a network and an apparatus thereof.
  • MTU maximum transmission unit
  • IPv4 Internet Protocol version 4
  • IPv6 Internet Protocol version 6
  • IPv4 when the size of a packet is greater than a link MTU, a router located on a routing path performs fragmentation of a packet.
  • IPv6 unlike in the IPv4, if a packet is once transmitted by a source node, a node in the middle of a path does not perform fragmentation of the packet. Instead, the source node searches for a minimum MTU on a path, fragments packets according to the discovered MTU, and transmits fragmented packets.
  • a link MTU of a path through which a packet is transmitted is first discovered. That is, a path MTU (hereinafter referred to as "PMTU") that is a minimum link MTU in a routing path between the source node and the destination node should be determined.
  • PMTU path MTU
  • the source node when a source node first transmits a packet, the source node fragments the packet in units each having the size of a next-hop link MTU and transmits the fragmented packet.
  • FIG. 1 is a diagram showing a process of PMTU discovery by using the prior art PMTU discovery method when the link MTU between a source node 1 10 and a destination node 150 decreases in the order of 6, 5, 4, and 3.
  • the method for PMTU discovery according to the prior art PMTU discovery method will now be explained.
  • the present invention provides a method and apparatus for more efficient PMTU discovery.
  • a method for discovery of a path maximum transmission unit (PMTU) among nodes on an Internet protocol (IP) network comprising: (a) comparing the size of a received packet with a maximum transmission unit (MTU) of a next link; and (b) if the size of the received packet is greater than the MTU of the next link, generating an error message, transmitting the generated error message to a source node, generating a test message of the size of the MTU of the next link, and transmitting the generated test message to a destination node.
  • the error message is an Internet Control
  • IPv6 Internet Protocol version 6
  • test message is an ICMP information message which uses one of bits [128:255] in a "Type" field of an ICMP message of IPv6.
  • the error message generated in the step (b) contains MTU information of a next link.
  • test message generated in the step (b) contains source address and destination address information of the received packet.
  • the method further comprises (c) storing MTU information, source address information and destination address information contained in the received packet, wherein the received packet is a test message generated by a previous node.
  • the method further comprises (d) comparing the MTU information, source address information, and destination address information of a packet received after transmitting the error message generated in step (b) to the source node, with the MTU information, source address information, and destination address information stored in step (c), and if the information in these comparisons is the same, transmitting the error message generated in step (b) without generating an error message and a test message, and then discarding the received packet.
  • an apparatus for discovery of a path maximum transmission unit (PMTU) among nodes on an Internet protocol (IP) network comprising: a determining unit which determines whether or not the size of a received packet exceeds the MTU of a next link; an error message generation and transmission unit which if it is determined that the size of the received packet is greater than the MTU of the next link, generates an error message and transmits the generated error message to a source node; and a test message generation and transmission unit which generates a test message of the size of the MTU of a next link and transmits the generated test message to a destination node.
  • PMTU path maximum transmission unit
  • IP Internet protocol
  • the generated error message contains MTU information of a next link.
  • the generated test message contains source address and destination address information of the received packet. It is preferable that when the MTU information, source address information, and destination address information of a packet received after transmitting the generated error message to the source node are compared with the stored MTU information, source address information, and destination address information. If the information in these comparisons is the same, the generated error message is transmitted without generating an error message and a test message and the received packet is discarded.
  • the apparatus is any one of a router, a bridge, and a switch that support IPv6.
  • FIG. 1 is a diagram showing a prior art path maximum transmission unit (MTU) discovery method
  • FIG. 2 is a diagram of a basic header of Internet Protocol version 6 (IPv6) used in the present invention
  • FIG. 3A is a diagram showing a basic structure of an ICMPv ⁇ message used in the present invention
  • FIG. 3B is a diagram showing a basic structure of an ICMP-Packet
  • FIG. 4A is a diagram showing a basic structure of a modified ICMP-Packet Too Big message used in a preferred embodiment of the present invention
  • FIG. 4B is a diagram showing a basic structure of a newly defined
  • FIG. 5 is a diagram showing a path MTU (PMTU) method according to the present invention
  • FIG. 6 is a diagram showing a storage space shape of a node according to the present invention
  • FIG. 7A is a diagram showing time and hop count spent in PMTU discovery according to the prior art PMTU discovery method.
  • FIG. 7B is a diagram showing time and hop count spent in PMTU discovery by a PMTU discovery method according to a preferred embodiment of the present invention.
  • node a device that implements IPv6.
  • router a node that forwards IPv6 packets not explicitly addressed to itself
  • host any node that is not a router.
  • upper layer a protocol layer immediately above IPv6.
  • transport protocols such as TCP and UDP
  • control protocols such as ICMP path maximum transmission unit discovery (PMTU)
  • PMTU ICMP path maximum transmission unit discovery
  • Minimizing Packet a newly defined ICMP information message.
  • link a communication facility or medium over which nodes can communicate at the link layer.
  • packet an IPv6 header plus a payload.
  • link MTU the maximum transmission unit
  • path the set of links traversed by a packet between a source node and a destination node
  • MTU (PMTU) the minimum link MTU of all the links in a path between a source node and a destination node.
  • FIG. 2 is a diagram of a basic header of IPv6 used in the present invention. All packets of IPv6 begin with a basic header formed with 40 bytes. "Version” of FIG. 2 indicates the version of IP, and “Payload Length” indicates the length of an IP packet in units of bytes. "Next Header” indicates which extension header follows the IP basic header, and “Hop Limit” is used to restrict in units of hops a distance for transmitting an IP packet. "Source Address” and “Destination Address” indicate the address of a host transmitting a packet and the address of a destination to which the packet should be transmitted, respectively. The length of the address is 128 bits.
  • FIG. 3A is a diagram showing a basic structure of an ICMPv6 message used in the present invention.
  • type numbers 0 to 127 are used in transmitting a message on an error, and type numbers 128 to
  • FIG. 3B is a diagram showing a basic structure of an ICMP-Packet
  • the value in the "Type” field of the ICMPv6 message is set to 2, and the value in a "Code” field is usually set to 0 by a sender, and is neglected in a receiver.
  • "MTU” field indicates a next-hop link MTU value.
  • the destination address of an ICMP-Packet Too Big message is copied from the source address of the IP header of the received original packet.
  • FIG. 4A is a diagram showing a basic structure of a modified
  • the modified ICMP-Packet Too Big message shown in FIG. 4A has the same structure as that of the
  • PMTUD Minimizing Packet having a "Type” field value of 143, which will be explained later, the value in the "Code” field is set to 1.
  • the value in the "Code” field is 0 or 1.
  • the PMTU discovery method according to the present invention can be implemented.
  • FIG. 4B is a diagram showing a newly defined ICMP information message i.e., an ICMP-PMTUD Minimizing Packet used in the PMTU discovery method according to the present invention.
  • type numbers 128 to 255 can be used in an ICMP information message and type numbers 128 to 142 have been used.
  • a new ICMP information message having a "Type" field value of 143 is generated and used.
  • PMTU discovery method according to the present invention by using another "Type" field number that is not 143 and is not defined at present.
  • the value 143 indicating the PMTUD Minimizing Packet which is newly defined according to the present invention, is stored in the "Type" field of the ICMP information message shown in FIG. 4b, and the value stored in the "Code” field is set to 0.
  • next-hop link MTU value is stored.
  • the source address of the previous packet being discarded is stored as a source address value
  • the destination address of the previous packet being discarded is stored as a destination address value.
  • the newly defined ICMP information message that is, the PMTUD Minimizing Packet, is transmitted to the destination node unlike the ICMP Packet Too Big message. To make the size of the message meet the next-hop link MTU, the message is filled with dummy data.
  • the PMTU discovery method according to the present invention is performed by using the modified ICMP Packet Too Big message of FIG. 4A and the ICMP-PMTUD Minimizing Packet, that is, the newly defined ICMP information message of FIG. 4B.
  • the PMTUD discovery method of the present invention in a node on a routing path, if the next-hop link MTU is less than the size of the transmitted packet, the present node discards the packet transmitted by the source node, generates the ICMP-Packet Too Big message shown in FIG. 4A, and transmits the generated ICMP-Packet Too Big message to the source node.
  • the present node sends the ICMP-PMTUD Minimizing Packet which is generated to meet the next-hop link MTU, to the destination node.
  • the arbitrary node discards the transmitted ICMP-PMTUD Minimizing Packet, generates an
  • ICMP-Packet Too Big message containing the next-hop link MTU information, and transmits the message to the source node.
  • the value in the "Code" field of the ICMP-Packet Too Big message becomes 1.
  • the arbitrary node generates an ICMP-PMTUD Minimizing Packet which has the same as the next-hop link MTU, and transmits the packet to the destination node.
  • the source node after receiving the ICMP-Packet Too Big message having the "Code" field value of 0, the source node fragments the packet according to the link MTU value contained in the ICMP-Packet Too Big message and transmits the fragmented packet.
  • the source node receives an ICMP-Packet Too Big message having a "Code" field value of 1 before the source node transmits the packet fragmented according to the link MTU value contained in the ICMP-Packet Too Big message, the packet fragmented according to the link MTU value contained in the previous ICMP-Packet Too Big message should be discarded.
  • the source node Before transmitting the packet fragmented according to the link MTU value included in the ICMP-Packet Too Big message, if the source node receives an ICMP-Packet Too Big message having the "Code” field value of 0, the source node receives an ICMP-Packet Too Big message having the "Code” field value of 1 , the already fragmented packet is discarded, and the packet is again fragmented according to the size of the MTU value included in the ICMP-Packet Too Big message having the "Code” field value of 1 , and transmitted.
  • the transmitted packet is automatically discarded in a node which generated the ICMP-Packet Too Big message having the "Code" field value is 1.
  • a node which generates an ICMP-Packet Too Big message having the "Code" field value of 1 for example, a router, stores a source address, a destination address, and a PMTU value, which are stored in an ICMP-PMTUD Minimizing Packet transmitted from the previous node, in its storage space having the structure shown in FIG. 6, for example, a cache.
  • the duration for which these items can be stored in the cache is not long. These items should be stored only for a period for PMTU discovery, and after that time, these items are automatically deleted.
  • the node After storing these items, if a packet from the source node arrives at this node, the node compares the source address, destination address and PMTU value of the packet with the values stored in the cache of the node. If the values are the same, the node deems that the packet is a packet to which an ICMP-Packet Too Big message having the "Code" field value of 1 is not applied.
  • the node deems that the packet was fragmented by the previous ICMP-Packet Too Big message and transmitted before the ICMP-Packet Too Big message having the "Code” field value of 1 , the message which the node generated and transmitted, arrives at the source node, and discards the packet without generating an ICMP-Packet Too Big message having the "Code” field value of 0.
  • This is to prevent generating and transmitting again an ICMP-Packet Too Big message when a packet, which is again fragmented by an ICMP-Packet Too Big message that is transmitted by the previous node, arrives after an ICMP-Packet Too Big message having the "Code” field value generated and transmitted to the source. By doing so, the unnecessary use of network resources can be prevented.
  • FIG. 5 is a diagram showing an embodiment for PMTU discovery using a PMTU discovery method and apparatus according to the present invention when the link MTU between a source node 510 and a destination node 550 decreases in the order of 6, 5, 4, and 3.
  • FIG. 5 a PMTU discovery method using the modified ICMP-Packet Too Big message of FIG. 4A and the ICMP PMTUD Minimizing Packet, which is the newly defined ICMP information message of FIG. 4B according to the present invention, will now be explained.
  • the source node 510 which operates as a host, comprises a function unit which can distinguish whether the value of the "Code" field of the modified ICMP-Packet Too Big message is 0 or 1 , and immediately after this message is received, newly defines a PMTU, and retransmits a packet satisfying the size of the new PMTU.
  • Each of the first node 520, the second node 530, and the third node 540 comprises a function unit which can distinguish whether the "Code" field of the modified ICMP-Packet Too Big message is 1 or 0 as in the source node, and generates the modified ICMP-Packet Too Big message of FIG. 4A and the ICMP-PMTUD Minimizing Packet, which is the newly defined ICMP information message of FIG. 4B. Also, each of these nodes comprises a storage space, as shown in FIG.
  • a cache (not shown), for storing the source address, destination address, and previous PMTU information stored in the discarded ICMP-PMTUD Minimizing Packet, for a predetermined time, when the ICMP-PMTUD Minimizing Packet is discarded.
  • this message is an ICMP error message for the data packet, which is originally desired to be transmitted by the source node 510, the value in* the "Code" field is 0.
  • the value in the "Code" field is 1.
  • the second node 530 stores information stored in the "MTU", “Source Address,” and “Destination Address” fields of the previous ICMP-PMTUD Minimizing Packet, that is, the ICMP-PMTUD Minimizing Packet ⁇ transmitted by the first node 520, in a storage space, for example, a cache having the structure shown in FIG. 6.
  • the message since the message is about an ICMP-PMTUD Minimizing Packet ⁇ , the value in the "Code" field is 1.
  • the second node 530 discards the packet.
  • the second node 530 already stored information stored in "MTU", “Source Address,” and “Destination Address” fields of the ICMP-PMTUD Minimizing Packet ⁇ which was transmitted by the first node 520, in the cache. Since these values stored in the cache are the same as the information in the packet, the second node 530 does not generate a separate ICMP error message. By doing so, it is possible to prevent the unnecessary use of network resources.
  • FIGS. 7A and (b) show time and hop count used in PMTU discovery in a routing path, in which link MTU sequentially decreases, in the prior art PMTU discovery method and in the PMTU discovery method according to the present invention.
  • a PMTU can be determined in a shorter time and the number of used hop counters decreases, compared to the prior art PMTU discovery method.
  • the present invention may be embodied in code on a computer readable recording medium which can be read by a computer.
  • the computer readable recording medium includes ail kinds of recording apparatuses on which computer readable data are stored.
  • the computer readable recording media includes storage media such as magnetic storage media (e.g., ROM's, floppy disks, hard disks, etc.), optically readable media (e.g., CD-ROMs, DVDs, etc.) and carrier waves (e.g., transmissions over the Internet). Also, the computer readable recording media can be scattered on computer systems connected through a network and can store and execute a computer readable code in a distributed mode.
  • storage media such as magnetic storage media (e.g., ROM's, floppy disks, hard disks, etc.), optically readable media (e.g., CD-ROMs, DVDs, etc.) and carrier waves (e.g., transmissions over the Internet).
  • the computer readable recording media can be scattered on computer systems connected through a network and can store and execute a computer readable code in a distributed mode.
  • a PMTU can be determined in a shorter time, and it is possible to minimize the use of network resources, compared to the prior art PMTU discovery method.

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

L'invention concerne un procédé d'exploitation plus efficace d'un réseau, et plus particulièrement, un procédé de recherche d'une unité de transmission maximale à chemin de transmission (PMTU) entre des noeuds dans un réseau IP. Ce procédé consiste à : (a) comparer la taille du paquet reçu à l'unité de transmission maximale (MTU) d'une liaison suivante; et (b) si la taille du paquet reçu est supérieure à la MTU de la liaison suivante, produire un message d'erreur, transmettre le message d'erreur produit à un noeud source, produire un message d'essai correspondant à la taille de la MTU de la liaison suivante, et transmettre le message d'essai produit à un noeud destination. Selon le procédé de recherche de PMTU, une PMTU peut être déterminée dans un délai plus court, et i est possible de réduire au minimum l'utilisation des ressources de réseau.
EP03745468A 2002-03-29 2003-02-26 Procede de recherche de mtu a chemin de transmission dans un reseau ip et appareil correspondant Withdrawn EP1491004A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US36837802P 2002-03-29 2002-03-29
US368378P 2002-03-29
KR10-2002-0034131A KR100453055B1 (ko) 2002-03-29 2002-06-18 Ｉｐ 네트워크 상에서의 경로 ｍｔｕ 탐색 방법 및 그 장치
KR2002034131 2002-06-18
PCT/KR2003/000382 WO2003084144A1 (fr) 2002-03-29 2003-02-26 Procede de recherche de mtu a chemin de transmission dans un reseau ip et appareil correspondant

Publications (1)

Publication Number Publication Date
EP1491004A1 true EP1491004A1 (fr) 2004-12-29

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EP03745468A Withdrawn EP1491004A1 (fr) 2002-03-29 2003-02-26 Procede de recherche de mtu a chemin de transmission dans un reseau ip et appareil correspondant

Country Status (4)

Country Link
EP (1) EP1491004A1 (fr)
CN (1) CN1647453A (fr)
AU (1) AU2003215922A1 (fr)
WO (1) WO2003084144A1 (fr)

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CN100375433C (zh) * 2003-11-13 2008-03-12 中兴通讯股份有限公司 动态发现IPsec隧道PMTU的方法

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CN101374101B (zh) * 2007-08-22 2011-05-04 华为技术有限公司 一种传输复用报文的方法、设备及系统
CN101217770B (zh) * 2008-01-18 2011-04-27 中国移动通信集团福建有限公司 一种移动通信网络质量自动评估分析装置及方法
CN101552728B (zh) * 2009-05-12 2012-05-23 北京师范大学 一种面向IPv6的路径MTU发现方法及系统
US8121135B2 (en) 2009-06-23 2012-02-21 Juniper Networks, Inc. Discovering path maximum transmission unit size
CN104601409B (zh) * 2015-01-30 2018-01-09 新华三技术有限公司 一种mtu探测方法及装置
CN106817316B (zh) * 2015-12-02 2020-02-21 华为技术有限公司 探测路径mtu的方法、装置和系统
CN113660167A (zh) * 2021-09-18 2021-11-16 中国电信股份有限公司 防止无效报文转发方法、装置以及存储介质

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EP1104141A3 (fr) * 1999-11-29 2004-01-21 Lucent Technologies Inc. Systéme de génération des paquets composites

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Publication number Priority date Publication date Assignee Title
CN100375433C (zh) * 2003-11-13 2008-03-12 中兴通讯股份有限公司 动态发现IPsec隧道PMTU的方法

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AU2003215922A1 (en) 2003-10-13
CN1647453A (zh) 2005-07-27
WO2003084144A1 (fr) 2003-10-09

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