CN101977156B - Method, device and routing equipment for learning maximum transmission unit - Google Patents

Method, device and routing equipment for learning maximum transmission unit Download PDF

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CN101977156B
CN101977156B CN 201010549943 CN201010549943A CN101977156B CN 101977156 B CN101977156 B CN 101977156B CN 201010549943 CN201010549943 CN 201010549943 CN 201010549943 A CN201010549943 A CN 201010549943A CN 101977156 B CN101977156 B CN 101977156B
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mtu
bgp
ipv6
routing information
network
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CN 201010549943
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CN101977156A (en
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吴梦非
姚辉
林东豪
贾攀
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北京星网锐捷网络技术有限公司
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Abstract

The invention discloses a method, a device and routing equipment for learning the maximum transmission unit. The method comprises the following steps of: receiving border gateway protocol (BGP) routing information reaching an IPv6 network and informed by an upstream BGP neighbor in an IPv6 message transmission tunnel, wherein the BGP routing information carries a first maximum transmission unit (MTU) reaching a route of the IPv6 network and determined by the upstream BGP neighbor; detecting a second MTU corresponding to the next hop of the BGP route carried by the BGP routing information; comparing the size of the first MTU and the second MTU, taking the small value as the determined third MTU reaching the BGP route of the IPv6 network, and saving the small value; and when a downstream BGP neighbor is present in the tunnel is determined, carrying the third MTU in the BGP routing information reaching the IPv6 network and informing the downstream BGP neighbor. The invention solves the problem of low message forwarding efficiency caused by transmission blockage and segmentation for multiple times of IPv6 messages in the transmission process.

Description

一种最大传输单元的学习方法、装置及路由设备 A method of learning the maximum transmission unit, and routing equipment device

技术领域 FIELD

[0001] 本发明涉及计算机网络通信技术领域,尤其涉及一种最大传输单元MTU的学习方法、装置及路由设备。 [0001] The present invention relates to computer network communication technology, and in particular, to a maximum transmission unit MTU of the learning method, apparatus and routing equipment.

背景技术 Background technique

[0002] 现有互联网协议版本6 (IPv6)网络作为下一代网络,目前尚未完全普及,仍然作为孤岛网络分散在互联网协议版本4(IPv4)网络之中。 [0002] the existing Internet Protocol version 6 (IPv6) network as the next generation network, has not yet completely universal, still dispersed in Internet Protocol version 4 (IPv4) network as an island network. 为了实现这些IPv6网络能够通过IPv4网络实现互联互通,一般采用隧道技术,如利用互联网协议版本4-多协议标签交换(IPv4-MPLS)网络提供IPv6报文传输隧道,从而实现IPv6孤岛网络的互联互通,互联网工程任务组(The Internet EngineeringTask Force, IETF)为该方案制定了相应的标准,称其为IPv6运营商边界(IPv6Provider Edge,6PE)方案。 To achieve these IPv6 network to the IPv4 network to achieve interoperability, tunneling technology is generally used, such as using the Internet Protocol version 4- Multiprotocol Label Switching (IPv4-MPLS) network provides a transmission tunnel IPv6 packets, enabling isolated IPv6 network interconnection , the Internet Engineering task Force (the Internet EngineeringTask Force, IETF) to develop the appropriate standards for the program, called IPv6 provider Edge (IPv6Provider Edge, 6PE) program. [0003] 图I所示是采用6PE方案实现IPv6网络互联的一个具体例子,该例子为单个自治域(Autonomous System,AS)内的IPv6网络的互联互通,在图I中,路由设备6PE_1、6PE_2、运营商路由器(Provider,简称P)和6PE-3组成了整个IPv4MPLS网络,其中P设备为网络中IPv4单协议栈路由设备,其他各设备均支持IPv6、IPv4双协议栈。 [0003] As shown in Figure I is employed to achieve a specific example embodiment 6PE IPv6 network interconnection, the interconnection examples IPv6 network within a single autonomous system (Autonomous System, AS), in FIG I, the routing device 6PE_1,6PE_2 operators router (provider, abbreviated P), and the entire composition 6PE-3 IPv4MPLS network, wherein the network device is a P single stack IPv4 routing device, each of the other devices support IPv6, IPv4 dual protocol stacks. 6ΡΕ-1、6ΡΕ_2、6ΡΕ_3之间通过内部边界网关协议(Internal Border Gateway Protocol, IBGP)分发带标签的IPv6路由信息,以6PE-1通告IPv6网络地址SI为例,6PE-1通过多协议内部边界网关协议(Multiprotocol-IBGP,MP-IBGP)协议向6PE-3通告带标签的IPv6路由,网络地址为SI,对应的标签值为Ll,6PE-3在收到该标签路由之后,将添加IPv6路由,出标签为LI,下一跳为6PE-1,这样IPv6S3网络中即存在到达SI的IPv6路由了。 Between 6ΡΕ-1,6ΡΕ_2,6ΡΕ_3 by an internal border gateway protocol (Internal Border Gateway Protocol, IBGP) IPv6 routing information distribution tagged to 6PE-1 SI advertise IPv6 network address as an example, multi-protocol 6PE-1 inner boundary gateway protocol (Multiprotocol-IBGP, MP-IBGP) IPv6 routing protocol to advertise tagged 6PE-3, the network address of the SI, the corresponding tag value Ll, 6PE-3 after receiving the routing tag, add IPv6 routing , the label LI, next hop 6PE-1, so that there is IPv6S3 IPv6 network to route to the SI. 同样的原理可以实现S1、S2、S3之间IPv6路由互联互通。 The same principle can be implemented IPv6 routing interconnection between S1, S2, S3.

[0004] 下面描述IPv6报文如何在MPLS网络中传输,6PE-3在收到目的地址为SI的IPv6报文时,将查找本地IPv6路由表,确认下一跳为6PE-1,且出标签为LI (该报文由6PE-1分发),之后6PE-3为该IPv6报文封装上标签LI,同时查找下一跳6PE-1的出口。 [0004] The following describes how an IPv6 packet transmitted in the MPLS network, 6PE-3 destination address in the SI received IPv6 packet, it will look up the local IPv6 routing table, the next hop is confirmed 6PE-1, and the label It is LI (packet distributed by 6PE-1), after 6PE-3 on the package label for LI IPv6 packets, while the outlet find the next hop 6PE-1. 根据MPLS转发表确定要达到6PE-1,需要插入标签Tl (为6PE-3到6PE-1的MPLS隧道标签),并转发至P,此时原来的IPv6报文将包含双层标签,内层标签为IPv6路由标签(LI),而外层标签为MPLS隧道标签(Tl)。 The MPLS forwarding is determined to achieve 6PE-1, need to insert the tag Tl (an MPLS tunnel label 6PE-3 to 6PE-1) and forwarded to P, the original IPv6 packet at this time will contain double-label, inner layer IPv6 routing label is a label (LI), while the outer label is an MPLS tunnel label (Tl). P在收到该报文之后,它不关心报文中封装的是IPv4数据还是IPv6数据,根据外层标签Tl确定该报文将转发至6PE-1,并交换标签Tl为T2,此时报文的标签栈变为T2/L1。6PE-1在收到该报文之后,将弹出标签T2,同时根据IPv6标签LI确定转发至正确的网段。 P After receiving the message, it does not concern the packet is encapsulated in an IPv4 or IPv6 data, forwards the packet to determine 6PE-1, and the label switching according to the outer label Tl T2 Tl is, at this time the packets the label stack becomes T2 / L1.6PE-1 after receiving the message, the pop-up tag T2, while LI forwarded to the correct determination of the label according to the IPv6 network segment.

[0005] 上述IPv6报文在传输中容易碰到两个问题,一方面,IPv4网络中的设备P在转发报文时将执行最大传输单兀(Maximum Transmission Unit, MTU)检查即检查该报文长度是否超过出接口的MTU,若当前接收的报文的长度超过其出接口的MTU时,P由于无法识别IPv6报文而只能丢弃该报文;另一方面,即使报文的长度未超过P出接口的MTU,由P成功转发至6PE-1,6PE-1根据该报文的标签LI以及IPv6路由确认转发至某个出接口,若当前报文的长度超过6PE-1出接口的MTU时,6PE-1将为该IPv6报文再次执行分片,这样导致IPv6报文在经隧道传输过程被多次分片,降低了报文转发效率。 [0005] In the above-described IPv6 packet transmissions likely to encounter two problems, on the one hand, the IPv4 network devices when forwarding the packet P will perform a maximum transmission unit Wu (Maximum Transmission Unit, MTU) checks whether the packet check i.e. whether the length exceeds the MTU of the interface, if the current length of the received packets out of the interface exceeds the MTU, because P can not only recognize the IPv6 packet discards the packet; on the other hand, even if the packet length is not exceeded the interface MTU P, P successfully forwarded to 6PE-1,6PE-1 are forwarded to an egress interface according to IPv6 routing label and LI acknowledgment packet, if the current length of the packet over an interface 6PE-1 MTU when, 6PE-1 for the IPv6 packet fragmentation performed again, which results in the IPv6 packet is fragmented in several tunneled process, reducing the efficiency of packet forwarding.

[0006] 图2所示是采用6PE方案实现IPv6网络互联的另外一个具体例子,该例子为跨多个自治域的IPv6网络的互联互通,图2中ASl由6PE-1、P和自治系统边界路由器(Autonomous System Border Router, ASBR) I 组成,AS2 由ASBR2 和6PE-2 组成(ASBR2 和6PE-2之间还可以包括若干P设备,在图2中未示意出),IPv6Sl通过6PE-1连接自治域AS I,IPv6S2连接自治域AS2,6PE-1和ASBRl之间建立MP-IBGP连接,6PE-1将带标签的IPv6路由通告给ASBRl,ASBRl与ASBR2之间建立多协议BGP协议(Multiprotocol ExtensionsBGP,MP-EBGP)连接,ASBRl 将6PE-1 的带标签IPv6 路由通过MP-EBGP 通告至ASBR_2,ASBR2与6PE-2建立MP-IBGP连接,ASBR2再将ASBRl通告的带标签IPv6路由通过MP-IBGP通告至6PE-2,这样6PE-2即可学习到6PE-1的带标签Ipv6路由,S2和SI相互学习到各自的IPv6路由。 [0006] FIG. 2 is a specific example of using the additional program to achieve 6PE IPv6 networks, which is an example of an IPv6 network interoperability across multiple autonomous domains, in FIG. 2 by the ASl 6PE-1, P and ASBRs router (Autonomous System Border router, ASBR) I composition, and the AS2 ASBR2 6PE-2 of the composition (P may further include a plurality of devices, not illustrated in FIG. 2 and the ASBR2 between 6PE-2), IPv6Sl 6PE-1 via autonomous AS I, IPv6S2 connection establishment MP-IBGP connection, 6PE-1 IPv6 route advertisement with the label to establish a multi-protocol between ASBRl, ASBRl with ASBR2 BGP protocol (multiprotocol ExtensionsBGP between autonomous AS2,6PE-1 and ASBRl , MP-EBGP) is connected, ASBRl connecting tagged 6PE-1 IPv6 routing through MP-EBGP advertisement to ASBR_2, ASBR2 6PE-2 and MP-IBGP established, then tagged ASBRl IPv6 routes advertised by ASBR2 MP-IBGP Notice to 6PE-2, so 6PE-2 can learn the route to a labeled Ipv6 6PE-1, S2, SI, and learn from each other to a respective IPv6 routing.

[0007] IPv6报文的转发则是通过建立三个MPLS隧道来实现的,如图2示中的T3(6PE_1和ASBRl之间的隧道)、T2 (ASBR1和ASBR2之间的隧道)和Tl (ASBR2和6PE-2之间的隧道),6PE-2在收到到达SI的IPv6报文之后,将会先通过隧道Tl将报文转发至ASBR2,ASBR2再通过隧道T2转发至ASBR1,ASBRl则通过MPLS隧道T3将报文转发至6PE-1,从而实现IPv6报文的转发。 [0007] IPv6 packet is forwarded through the MPLS tunnel establishment of three to be achieved, as shown in FIG. 2 shows the T3 (between the tunnel and the 6PE_1 ASBRl), T2 (tunnel between ASBR1 and the ASBR2) and Tl ( tunnel between and 6PE-2 ASBR2), 6PE-2 after reaching the SI received IPv6 packets, the first through the tunnel will Tl forwards packets to ASBR2, ASBR2 and then forwarded through the tunnel to T2 ASBR1, ASBRl through MPLS tunnel T3 forwards packets to 6PE-1, enabling IPv6 packet forwarding. 由于6PE-2不需要知道如何到达ASBRl和6PE-1,它只需要将报文转发至ASBR2,剩余的转发操作则有ASBR2来执行,报文转发至ASBR2时,ASBR2会进行MTU检查,如果报文的长度超过其出接口的MTU,那么需要执行分片后转发,类似地,ASBR2和6PE-2在转发过程也同样需要进行MTU的检查,这样可能导致IPv6报文在经隧道传输过程被多次分片,降低了报文转发效率。 Since 6PE-2 and does not need to know how to get ASBRl 6PE-1, only needs to forward packets to ASBR2, remaining there ASBR2 forwarding operation is performed, the packet when forwarded to ASBR2, ASBR2 MTU will be checked, if the reported the length of the text exceeds its outgoing interface MTU, so the need to perform fragmentation forwarding, similarly, the ASBR2 and 6PE-2 forwarding process also needs to be checked the MTU, this may lead to IPv6 packets are multiplexed in the transmission tunneled secondary fragmentation, reducing the efficiency of packet forwarding. 另外,报文在经由ASl和AS2中的P设备转发至边界路由设备时,也有可能因为其长度大于P设备出接口的MTU而使得P设备直接丢弃该报文,使得IPv6报文的传输过程受阻导致IPv6网络之间无法实现互通。 Further, when a packet is forwarded to the boundary routing device via ASl and AS2 P device, may also because of its length is larger than the MTU P outbound interface is such that the P device directly discards the packet, so that the transmission process IPv6 packets hindered cause can not achieve interoperability between IPv6 network.

发明内容 SUMMARY

[0008] 本发明实施例提供一种最大传输单元MTU的学习方法、装置及路由设备,用以解决在现有6PE技术中IPv6报文在传输过程中由于长度大小超过路由设备出接口MTU导致传输受阻以及被多次分片导致的报文转发效率低的问题。 [0008] The learning method, apparatus, and routing apparatus according to the present invention provides a MTU of the to solve the prior art 6PE IPv6 packets during transmission because the length larger than the MTU of the routing device result in transmission disruption and low packet forwarding efficiency is caused by multiple fragmentation.

[0009] 本发明实施例提供的一种最大传输单兀的学习方法,包括: [0009] A method of learning the maximum transmission unit Wu according to an embodiment of the present invention, comprising:

[0010] 对于IPv4网络中形成的IPv6报文传输隧道中的每个运行边界网关协议BGP的路由设备执行下述操作: [0010] The following operations are performed for the transmission tunnel IPv6 packets in IPv4 network is formed for each run Border Gateway Protocol BGP routing devices:

[0011] 接收IPv6报文传输隧道中上游边界网关协议BGP邻居通告的到达IPv6网络的BGP路由信息;所述BGP路由信息中携带有所述上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; [0011] receive IPv6 packets tunnelled upstream neighbor advertisement Border Gateway Protocol BGP BGP routing information reaching the IPv6 network; the BGP routing information carries the first upstream neighbor BGP IPv6 network reaches the determined route MTU;

[0012] 对接收的所述BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第 [0012] the BGP routing information carried in the received BGP route arrives at the first hop IPv6 network corresponding to

二 MTU进行探测; Detect two MTU;

[0013] 比较所述第一MTU与探测到的第二MTU的大小,将两者中的较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; [0013] comparing the first MTU with the second MTU size is detected, whichever is smaller as a third determined MTU BGP routes reaching the IPv6 network and stored;

[0014] 确定所述隧道中是否还存在下游BGP邻居,若存在,将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居;若不存在,则结束MTU的学习过程。 [0014] determines if the BGP peer is present Xiayou tunnel, if present, the third carries the MTU of the downstream neighbor BGP BGP routing information reaching the IPv6 network and to advertise; if not, the end of MTU learning process.

[0015] 本发明实施例提供的一种最大传输单元的学习装置,包括: [0015] maximum transmission unit learning apparatus according to an embodiment of the present invention, comprising:

[0016] BGP路由信息接收单元,用于接收IPv6报文传输隧道中上游边界网关协议BGP邻居通告的到达IPv6网络的BGP路由信息;所述BGP路由信息中携带有所述上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; [0016] BGP routing information receiving means for receiving a transmission tunnel IPv6 packets in an upstream neighbor advertisement Border Gateway Protocol BGP BGP routing information reaching the IPv6 network; the BGP routing information carries the upstream of the determined neighbor BGP the first arrival MTU IPv6 network routing;

[0017] MTU探测单元,用于对接收的所述BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测; [0017] MTU detection means for receiving the arrival of BGP routing information carried in the BGP routing a second MTU of the next hop corresponding to the IPv6 network detect;

[0018] 比较单元,用于将比较所述第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; [0018] The comparing unit for comparing the first MTU with the second MTU size is detected, a smaller value as the determined IPv6 network BGP route to both the third and stored MTU;

[0019] 路由通告单元,用于确定所述隧道中是否还存在下游BGP邻居,若存在,将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居。 [0019] route advertisement means, for determining whether there is downstream of the tunnel BGP peer, if present, the third carries the MTU downstream neighbor BGP BGP routing information reaching the IPv6 network and to advertise.

[0020] 本发明实施例提供的路由设备,包括本发明实施例提供的上述最大传输单元的学习装置。 The routing device according to an embodiment [0020] of the present invention, including the above-described learning device according to an embodiment of the maximum transmission unit of the present invention.

[0021 ] 本发明实施例的有益效果包括: [0021] Advantageous effects of the embodiments of the present invention comprises:

[0022] 本发明实施例提供的最大传输单元的学习方法、装置及路由设备,对于IPv4网络中形成的IPv6报文传输隧道中的每个运行BGP的路由设备,执行下述操作即:接收上游BGP邻居通告的到达IPv6网络的BGP路由信息;该BGP路由信息携带有该上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ;对接收的BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测;比较第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存;如果还存在下游BGP邻居,则将第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至下游BGP邻居,直至该隧道中的每个运行BGP的路由设备都学习到了到达该IPv6网络的BGP路由对应的MTU0本发明实施例在支持BGP协议的运营商边界设备和自治系统边界路由之间通过BGP路由传递MTU的值,使得传输IPv6 [0022] The method of learning, the maximum transmission and routing equipment apparatus according to an embodiment of the present invention means, for each running BGP transmission tunnel IPv6 packets in IPv4 network routing devices are formed, i.e., performing the following: receiving an upstream BGP peer BGP routing information reaching the advertised IPv6 network; BGP routing information carries the MTU of the first upstream neighbor BGP reaches the determined IPv6 network routing; BGP routing information carried in the received BGP route reaches the IPv6 network the second MTU detect corresponding next hop; second comparing a first MTU size MTU is detected, the smaller of the two values ​​as the determined MTU third BGP route reaching the IPv6 network and stored; if there is also the downstream BGP neighbor, then the third MTU is carried in the BGP routing information to reach the IPv6 network and BGP announcement to the downstream neighbor, until the tunnel each running BGP routing devices have learned to reach the IPv6 BGP network MTU0 embodiment of the present invention according to the corresponding route passed by the MTU value BGP routes between PE device and an autonomous system border router support BGP protocol, so that the transmission IPv6 报文的隧道的终点即连接另一IPv6网络的运营商边界设备可以计算出到达目的IPv6网络的路由中各跳的MTU的最小值,并将其作为发送IPv6报文是否需要进行分片的依据,经过上述过程之后,在该隧道的终点收到发往该IPv6网络的IPv6报文时,将该报文的大小与自身保存的MTU的大小进行比较,决定是否需要分片,如果进行分片,分片后的报文的长度是到达该IPv6网络的路由中各跳MTU的最小值,因此,对于通过IPv4网络实现IPv6网络的互联互通的应用场景尤其是跨多个IPv4自治域实现IPv6网络的互联互通的应用场景来说,不论IPv4网络中传输IPv6报文的隧道需要跨越多少中间设备(例如P设备)或边界设备,任何中间设备或者边界设备,都不会因为IPv6报文长度的大小超出了该路由设备出接口的MTU的大小而丢弃该IPv6报文,从而避免了现有6PE技术出现的IPv6报文的传输受阻的 The end of the tunnel that is connected to the other packets of IPv6 network boundary device operator can calculate the minimum MTU route to the destination IPv6 network hops, and whether the packet needs to be fragmented in accordance with a transmission IPv6 when, after the above process, at the end of the tunnel receipt sent to the IPv6 network an IPv6 packet, the packet size and the size of their own to save the MTU are compared to determine whether to fragment, if fragmentation , the length of the packet is fragmented route to the IPv6 network hops MTU minimum, thus achieving interoperability scenarios IPv6 network through an IPv4 network, especially across multiple autonomous domain implementation IPv4 IPv6 network application scenarios for interoperability, regardless of how many intermediate IPv4 network transmission device (e.g. P device) or edge device requires a tunnel IPv6 packets across any intermediate device or edge device are not because of the size of the IPv6 packet length exceeds the MTU size of the routing device of an IPv6 interface discards the packet, thus avoiding the IPv6 packet transmission occurring prior art hindered 6PE 情况,并且在该隧道的终点对收到的IPv6报文进行分片操作后,该隧道中其他路由设备也不会再执行报文的分片操作,提高了IPv6报文在隧道中转发效率。 After the situation, and receiving an IPv6 packet slicing at the end of the tunnel, the tunnel will not be other routing devices slicing a packet, the IPv6 is improved in the efficiency of the tunnel.

附图说明 BRIEF DESCRIPTION

[0023] 图I为现有技术中6PE方案实现IPv6网络互联的网络连接示意图之一; [0023] Figure I is a schematic view of one of the connection scheme of IPv6 6PE network interconnection network prior art;

[0024] 图2为现有技术中6PE方案实现IPv6网络互联的网络连接示意图之二;[0025] 图3为本发明实施例提供的最大传输单元的学习方法的流程图; [0024] FIG. 2 is a prior art program to achieve 6PE IPv6 networks network connection diagram of the two; [0025] FIG 3 a flow diagram of a method of learning the maximum transmission unit provided in the embodiment of the present invention;

[0026] 图4为自定义团体属性的格式示意图; [0026] FIG. 4 is a schematic diagram format custom community attributes;

[0027] 图5为本发明实施例提供的第一个具体实例的网络连接示意图; [0027] FIG 5 A specific example of the first network according to an embodiment of the present invention, connection diagram;

[0028] 图6为本发明实施例提供的最大传输单元的学习装置的结构示意图。 [0028] FIG. 6 is a schematic configuration provides a maximum transmission unit of the learning apparatus of the embodiment of the invention.

具体实施方式[0029] 下面结合附图,对本发明实施例提供的一种最大传输单元(MTU)的学习方法、装置及路由设备进行详细地说明。 DETAILED DESCRIPTION [0029] below with reference to the accompanying drawings, the present invention is one kind of the maximum transmission unit (MTU) to provide learning methods, apparatus and routing equipment be described in detail embodiments.

[0030] 本发明实施例提供的MTU学习方法,如图3所示,包括如下步骤: [0030] MTU learning method according to an embodiment of the present invention, shown in Figure 3, comprising the steps of:

[0031 ] S301、接收IPv6报文传输隧道中上游BGP邻居通告的到达IPv6网络的BGP路由信息;该BGP路由信息中携带有该上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; [0031] S301, receiving the upstream neighbor advertisement BGP BGP routing information reaching the IPv6 network an IPv6 packet transport tunnel; the BGP routing information carries the upstream neighbor BGP reaches a first determined route MTU IPv6 network;

[0032] S302、对接收的BGP路由信息携带的到达该IPv6网络的BGP路由下一跳的第二MTU进行探测; [0032] S302, the BGP routing information carried in the received reaches a second MTU of the next hop BGP routing detect IPv6 network;

[0033] S303、比较所述第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; [0033] S303, the first comparing the second MTU size MTU is detected, the smaller of the two values ​​as the determined MTU third BGP route reaching the IPv6 network and stored;

[0034] S304、确定IPv6报文传输隧道中是否还存在下游BGP邻居;若存在,执行下述步骤S305 ;若不存在,结束本流程; [0034] S304, determines whether there is a downstream neighbor BGP IPv6 packet transport tunnel; if present, performing the steps S305; if not, the process ends;

[0035] S305、将第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至下游BGP邻居。 [0035] S305, the third MTU is carried in the BGP routing information reaching the IPv6 network and notify to the downstream BGP neighbor.

[0036] 上述步骤S301中,IPv6报文传输隧道指的是连接两个IPv6网络的IPv4_MPLS网络提供的IPv6报文传输通道。 [0036] In step S301, the IPv6 packet refers to a transmission tunnel connecting two IPv4_MPLS network provides IPv6 network an IPv6 packet transmission channel.

[0037] 上述步骤S301和步骤S305中,在到达IPv6网络的BGP路由信息中携带第一MTU或携带第三MTU,可以通过下述方式实现:自定义BGP路由信息中的扩展团体属性,将第一MTU或第三MTU的值封装在所述扩展团体属性的Value字段中。 [0037] The above-described steps S301 and S305, or carries a third carries the MTU of the first MTU, the following manner may be achieved by the BGP routing information reaching the IPv6 network: Custom BGP routing information in the extended community attribute, the first a third MTU value MTU or encapsulating the extended community attribute in the value field.

[0038] 扩展团体属性(Extended Communities Attribute)是BGP路由信息中的路由属性中的一类,其格式如图4所示,自定义团体属性,可以自定义其中的type字段(扩展团体属性的类型)为MTU,将第一MTU或者第三MTU的值封装在自定义的扩展团体属性的Value字段中。 [0038] extended community attributes (Extended Communities Attribute) routing attribute in the BGP routing information for a class of which the format shown in Figure 4, custom community attribute, which can customize the type field (type extended community attributes ) for the MTU, the MTU of the first MTU or the third value from the package in the extended community attribute value field definition.

[0039] 较佳地,在本发明实施例中,还需要同时保存本次MTU学习过程中得到的第一MTU和第二MTU也与到达IPv6网络的BGP路由信息,以便后续MTU发生变化时,可以及时根据保存的第一MTU和第二MTU对保存的第三MTU进行更新。 When [0039] Preferably, this embodiment also need to save the first and second MTU information MTU also reach BGP routing IPv6 network obtained during this study MTU, so that subsequent changes in the MTU embodiment of the present invention, and a second pair of timely MTU stored MTU is updated according to a third first MTU stored.

[0040] 下面结合两个具体的实例,对本发明实施例提供的MTU学习方法进行详细地说明。 [0040] below with reference to two specific examples, MTU learning method provided by the embodiment of the present invention will be described in detail.

[0041] 第一个实例: [0041] First Example:

[0042] 本实例采用图5所示的单自治域内IPv6网络互联的网络拓扑,运营商边界设备Rl与IPv6Sl网络相连,运营商边界设备R2与IPv6S2网络相连,同时Rl和R2同属于IPv4-MPLS网络,为了实现将IPv6S2网络的IPv6报文发送至IPv6Sl网络,需要在报文发送之前,执行BGP协议的路由设备Rl和R2按照下面的流程分别执行MTU学习的步骤: [0042] This example uses a single autonomous network topology IPv6 networks art shown in FIG. 5, the edge device connected to the operator network IPv6Sl and Rl, R2 are connected with PE device IPv6S2 network, and Rl and R2 belonging to the same IPv4-MPLS network, in order to achieve IPv6 packets sent to the network IPv6S2 IPv6Sl network, it is necessary before sending packets, BGP routing protocol execution device Rl and R2 according to the following process step MTU study were:

[0043] 步骤1、R1向IPv6报文传输隧道中其上游的BGP邻居即R2通告到达IPv6Sl网络的BGP路由信息,在通告的BGP路由中携带有Rl确定出的到达IPv6SI网络的路由的MTUl ; [0043] Step 1, R1 to IPv6 packet transmission tunnel upstream BGP peer i.e. R2 advertised BGP routing information reaches IPv6Sl network carried in BGP route advertisement has Rl the determined route to the IPv6SI network MTUl;

[0044] 在本步骤I中,由于Rl是直接与IPv6Sl网络相连的运营商边界设备,MTUl的值,Rl可以通过获取Rl中与到达IPv6Sl网络的路由对应的出接口的MTU的值得到MTU1。 [0044] In the step I, since Rl is PE device directly connected to IPv6Sl network, MTUl value, Rl may be the route to IPv6Sl network corresponding by obtaining Rl out MTU worth interface to MTU1.

[0045] Rl将MTUl的值携带在自定义的扩展团体属性中,具体方法参见前述步骤S301的说明。 [0045] Rl carries the value in the custom MTUl extended community attribute, refer to the specific method described in the aforementioned step S301.

[0046] 步骤2、R2接收到该BGP路由信息之后,对该BGP路由信息携带的到达IPv6Sl网络的路由的BGP路由下一跳对应的MTU2进行探测; After [0046] Step 2, R2 receiving the BGP routing information, the routing information carried in BGP BGP route to reach the next hop route network IPv6Sl corresponding MTU2 detect;

[0047] R2从接收的BGP路由信息中提取该BGP路由的下一跳的IP地址,BGP路由的下一跳是BGP路由信息中路由属性的一种,用于指明到达该路由前缀对应的网络(IPv6Sl网络)需要将报文转发至BGP下一跳的路由设备(即Rl)。 [0047] R2 extracts the BGP route information received from the BGP routing next hop IP address, the next hop BGP route is a route to BGP attribute information for indicating the route reaching the corresponding network prefix (IPv6Sl network) packet needs to be forwarded to the BGP next hop routing equipment (ie, Rl).

[0048] 根据该BGP路由的下一跳(Rl)的IP地址,R2可自动探测该下一跳对应的MTU 值。 [0048] According to the next hop (Rl) of the IP address of the BGP routing, R2 of automatically detects the MTU value corresponding to the next hop. 具体可采用现有的自动探测方法,例如通过发送Internet控制报文协议(InternetControl Message Protocol, ICMP)报文来发现MTU2,如果该传输隧道中Rl和R2之间的路径上还连接有若干P设备或其他路由设备,探测MTU2的过程,即确定从R2经过若干P设备或其他路由设备到达Rl的路径中各跳的MTU值的最小值。 DETAILED conventional automatic detection method may be employed, for example, by sending Internet Control Message Protocol (InternetControl Message Protocol, ICMP) packet to find the MTU2, if the tunnel is also connected to the transmission path between the Rl and R2 have several devices P or other routing devices, MTU2 detection process, i.e. after determining a plurality of P devices, or other routing device becomes the minimum value of the path MTU in Rl hops from R2. 具体探测方法属于现有技术,在此不再赘述。 Specific detection methods belonging to the prior art, are not repeated here.

[0049] 步骤3、R2比较MTUl和MTU2两者的大小,将两者中的较小值确定为到达IPv6Sl网络的BGP路由对应的MTU3并保存。 [0049] Step 3, R2 and size of both the comparison MTUl MTU2, whichever is smaller is determined as the arrival of BGP routing network IPv6Sl corresponding MTU3 and stored.

[0050] MTU3可以与到达IPv6Sl网络的BGP路由一起保存于路由表中,以便在后续在转发该路由的IPv6报文时,可以根据MTU3的大小判断是否需要对报文进行分片的操作。 [0050] MTU3 can be saved with the BGP route to IPv6Sl together in a network routing table, in order to follow the route forwarding the IPv6 packet, the packet may need to operate according to the size of the fragment is determined MTU3.

[0051] 步骤4、R2判断该隧道中是否存在下游BGP邻居,由于R2是与IPv6S2网络相连的运营商边界设备,其不存在BGP邻居,因此流程到此结束。 [0051] Step. 4, R2 is present downstream of the BGP peer determines whether the tunnel, since R2 is the IPv6S2 PE device connected to the network, the BGP peer which does not exist, so the process ends.

[0052] 在经过上述步骤I〜4之后,R2中保存的是到达IPv6Sl网络的路由各跳MTU的最小值,R2收到IPv6S2网络发送至IPv6Sl网络的IPv6报文后,将该报文的大小与保存的MTU3的大小进行比较,决定是否需要分片,如果进行分片,分片后的报文的长度是到达IPv6Sl网络的路由的MTU的最小值,因此,在R2和Rl之间的P设备不会因为报文长度的大小超出了该路由出接口的MTU的大小而丢弃报文,在Rl中,也不会再执行报文的分片操作,提高了报文的转发效率。 [0052] After the above steps, after I~4, R2 is stored in a route network hops IPv6Sl minimum MTU, R2 is transmitted to the network after receiving IPv6S2 IPv6Sl IPv6 packet network, the packet size compared with the stored magnitude MTU3 decide whether to fragment, if the fragmentation, the length of the packet after the slice is the minimum MTU IPv6Sl a route network, therefore, P is between Rl and R2 because the size of the device does not exceed the length of the packet MTU size of the routing of the interface discards the packet, in Rl, and will not then perform packet slicing, efficient forwarding packets.

[0053] 第二个实例: [0053] Second Example:

[0054] 本实例采用图2所示的跨自治域的IPv6网络互联的网络拓扑,其中IPv6Sl网络通过ASl、AS2 与IPv6S2 网络相连,ASl 由6PE-1、P 和ASBRl 组成,AS2 由ASBR2 和6PE-2组成,ASl和AS2都属于IPv4-MPLS网络,6PE-1和6PE-2是运营商边界设备。 [0054] The present example uses network topology IPv6 networks inter-AS shown in FIG. 2, wherein the network through IPv6Sl ASl, AS2 and IPv6S2 connected to the network, the ASI 6PE-1, P and ASBRl composition, and the AS2 of ASBR2 6PE -2 compositions, ASl and AS2 are all IPv4-MPLS network, 6PE-1 and 6PE-2 is a PE device.

[0055] 为了实现将IPv6S2网络的IPv6报文发送至IPv6Sl网络,需要在报文发送之前,各执行BGP协议的路由设备按照下面的流程分别执行MTU学习的步骤: [0055] In order to achieve IPv6 packets sent to the network IPv6S2 IPv6Sl network, it is necessary before sending packets, each routing protocol BGP device performs the following process step MTU study were:

[0056] 步骤I'、6PE-1向ASBRl通告到达IPv6Sl网络的BGP路由信息,在通告的BGP路由中携带有6PE-1确定出的到达该IPv6Sl网络的路由的MTUl ; [0056] Step I ', 6PE-1 IPv6Sl arrival of BGP routing information to the network advertisement ASBRl carried in BGP routes have 6PE-1 in the determined route to the network IPv6Sl MTUl;

[0057] 与步骤S501相似,6PE-1通过路由信息中的扩展团体属性携带MTUl ;6PE_1向ASBRl通告的BGP路由信息中还包括该BGP路由的下一跳的信息,该BGP下一跳的信息为6PE-1的地址。 [0057] Similar to step S501, 6PE-1 carried by the extended community attribute MTUl routing information; 6PE_1 ASBRl BGP routing information to the advertisement further comprises the BGP next hop routes, the BGP next hop information address 6PE-1's. [0058] 步骤2'、ASBRl根据接收的BGP路由信息中的BGP下一跳的地址,对该BGP路由下一跳对应的MTU2进行探测; [0058] Step 2 ', ASBRl BGP next hop according to the routing information received BGP address, the BGP next-hop corresponding MTU2 detect;

[0059] 步骤3'、ASBRl比较MTUl和MTU2的大小,将两者之中较小值作为该BGP路由的MTU3值并保存。 [0059] Step 3 ', ASBRl comparison MTUl MTU2 size and, as the smaller value among two values ​​of the BGP routing MTU3 and stored.

[0060] 步骤4'、ASBRl确定该隧道中还存在下游BGP邻居ASBR2 ; [0060] Step 4 ', ASBRl determines that there is a downstream tunnel BGP neighbor the ASBR2;

[0061] 步骤5' ,ASBRl向ASBR2通告到达IPv6Sl网络的BGP路由信息,在该BGP路由信息中携带ASBRl确定出的到达该IPv6Sl网络的路由的MTU3。 [0061] Step 5 ', ASBRl BGP routing information advertised to the network reaches IPv6Sl ASBR2, MTU3 carrying route to the network ASBRl IPv6Sl determined in the BGP routing information.

[0062] 步骤6'、ASBR2接收该BGP路由信息之后,与ASBRl的处理方式类似,根据该BGP路由信息中的BGP下一跳(ASBRl)的地址,对该BGP路由下一跳对应的MTU4进行探测,ASBR2比较MTU4和MTU3的大小,将两者之中较小值作为该BGP路由的MTU5并保存。 [0062] Step 6 ', after receiving the ASBR2 BGP routing information, processing similar manner ASBRl The hop (ASBRl) address this BGP BGP routing information, for the next hop BGP route corresponding MTU4 detecting, comparing the ASBR2 MTU3 MTU4 and size as the smaller value among the two BGP route MTU5 and stored. ASBR2确定该隧道中还存在下游BGP邻居6PE-2,继续向6PE-2通告到达IPv6Sl网络的BGP路由信息,在该BGP路由信息中携带ASBR2确定出的到达该IPv6Sl网络的路由的MTU5。 ASBR2 determining the tunnel there is a downstream neighbor BGP 6PE-2, continue to be advertised 6PE-2 IPv6Sl arrival of BGP routing information of the network, carrying MTU5 route to the ASBR2 IPv6Sl network determined in the BGP routing information.

[0063] 步骤7'、6PE_2接收该BGP路由信息之后,与ASBR2的处理方式类似,根据该BGP路由信息中的BGP下一跳(ASBR2)的地址,对该BGP路由下一跳对应的MTU6进行探测;6PE-2比较MTU5和MTU6的大小,将两者之中较小值作为该BGP路由的MTU7并保存。 [0063] Step 7 ', after receiving the 6PE_2 BGP routing information, processing similar manner ASBR2 The hop (ASBR2) address this BGP BGP routing information, for the next hop BGP route corresponding MTU6 probe; 6PE-2 and Comparative MTU5 MTU6 size, the smaller value among the two as the BGP routing MTU7 and stored. 由于6PE-2是与IPv6S2网络直接相连的运营商边界设备,因此,MTU学习的流程到此结束。 Since 6PE-2 is a PE device and IPv6S2 directly connected network, therefore, MTU learning process ends.

[0064] 经过上述流程之后,6PE-2中保存的是到达IPv6Sl网络的路由的各跳MTU中的最小值,6PE-2收到IPv6S2网络发送至IPv6Sl网络的IPv6报文后,将该报文的大小与保存的MTU7的大小进行比较,决定是否需要分片,如果进行分片,分片后的报文的长度是到达IPv6Sl网络的路由中各跳的MTU的最小值,因此,在6PE-2和6PE-1之间的P设备不会因为报文长度的大小超出了该路由出接口的MTU的大小而丢弃该IPv6报文,并且在ASBR2、ASBRl和6PE-1中,也不会再执行报文的分片操作,提高了报文的转发效率。 [0064] After the above process, 6PE-2 is the minimum value stored in a route network hops IPv6Sl the MTU, 6PE-2 IPv6S2 received after sending the network packet to the IPv6 network IPv6Sl the packet size compared with the size of the stored MTU7 decide whether to fragment, if the fragmentation, the length of the packet is fragmented minimum MTU IPv6Sl route to network hops, and therefore, in 6PE- P between the device and the size will not 6PE-1 packet length exceeds the MTU size of the interface and the routing of the IPv6 packet is discarded, and the ASBR2, and the ASBRl 6PE-1, would no longer slicing a message to improve the efficiency of packet forwarding.

[0065] 在上述两个实例中,如果连接IPv6Sl网络的Rl或者6PE-1发现到达IPv6网络的路由对应的出接口的MTUl出现变化后,会向其下游邻居R2或ASBRl通告携带有更新后的MTUl的BGP路由信息,R2或ASBRl接收到该BGP路由信息后,会发现当前接收的BGP路由信息中的MTUl与保存的MTUl值不相等,这时,比较更新后的MTUl与本地保存的MTU2的大小确定两者之中的较小值,并在确定出的较小值与保存的MTU3不相等时,并使用该较小值更新保存的MTU3 ;如果是ASBR1,由于其还存在下游邻居ASBR2,那么还需要将更新后的MTU3携带在到达该IPv6的BGP路由信息中并通告至ASBR2,ASBR2接收到该路由信息后,执行类似的操作,直至MTU的计算在整个隧道中得到更新。 [0065] In the above two examples, if the network or connecting Rl IPv6Sl 6PE-1 found a route to correspond to the IPv6 network interface MTUl the change, after the update carries its downstream neighbor advertisement R2 or ASBRl after MTUl BGP routing information, R2, or ASBRl receiving the BGP route information, BGP will find the route information received and stored MTUl MTUl values ​​are not equal, then, after comparison with the local MTUl updated stored in MTU2 determining the size of the smaller value among the two, and it is determined that the smaller the value stored MTU3 not equal, the smaller value using the stored and updated MTU3; if the ASBR1, there is also due to its downstream neighbor the ASBR2, MTU3 then also need to update the routing information carried in BGP's IPv6 and reaching the advertisement to the ASBR2, after receiving the routing information the ASBR2, similar operations are performed until the calculated MTU is updated throughout the tunnel.

[0066] 在上述两个实例中,R2、ASBR1、ASBR2或6PE-2还可以在首次学习MTU的过程结束后,周期性对到达该IPv6网络的BGP路由下一跳对应的MTU进行自动探测,并根据自动探测的结果,对MTU学习的结果进行更新。 [0066] In the above two examples, R2, ASBR1, ASBR2 or 6PE-2 may also be MTU after the first learning process, the periodic arrival of BGP next hop route of the IPv6 network corresponding to the MTU automatic detection, and in accordance with the automatic detection of learning the results of MTU update. 以ASBRl为例,ASBRl在当前探测到的MTU2与保存的MTU2不相等时,则需要将当前探测到的MTU2的值与保存的该路由对应的MTUl值进行比较确定两者中的较小值,并当两者中的较小值与保存的MTU3不相等时,使用该较小值更新保存的MTU3,将更新后的MTU3携带在达到IPv6Sl网络的BGP路由信息中并通告至ASBR2,ASBR2收到后,按照前述更新方法对保存的MTU进行更新,直至连接IPv6S2网络的运营商边界设备6PE-2也更新了其保存的MTU7。 In ASBRl an example, when the current detected ASBRl MTU2 and stored MTU2 not equal, it is necessary to detect the current value with the stored routing MTU2 corresponding MTUl value whichever is smaller in comparison determination, and whichever is smaller when the stored MTU3 not equal, the smaller value is used to update the stored MTU3, MTU3 the updated routing information carried in the BGP achieve IPv6Sl network to advertise and ASBR2, ASBR2 received after updating method according to the stored MTU is updated, until the edge device connected to the operator network IPv6S2 6PE-2 also update its stored MTU7.

[0067] 基于同一发明构思,本发明实施例还提供了一种MTU学习装置及路由设备,由于该装置及设备解决问题的原理与前述一种MTU学习方法相似,因此该装置和路由设备的实施可以参见方法的实施,重复之处不在赘述。 [0067] Based on the same inventive concept, an embodiment of the present invention further provides a learning device MTU and routing equipment, since the principle of the apparatus and the device to solve problems similar to one of the foregoing MTU learning method, implementation of the apparatus and the routing device can refer to a method embodiment, repeated description of which is not repeated herein.

[0068] 本发明实施例提供的一种最大传输单元MTU的学习装置,如图6所示,包括: Figure 6 [0068] Study MTU of a device according to an embodiment of the present invention, FIG, comprising:

[0069] BGP路由信息接收单元601,用于接收IPv6报文传输隧道中上游边界网关协议BGP邻居通告的到达IPv6网络的BGP路由信息;所述BGP路由信息中携带有所述上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; [0069] BGP routing information receiving unit 601 for receiving the BGP routing IPv6 packets in an upstream transmission tunnels the IPv6 network border gateway protocol BGP reach neighbor advertisement; the BGP routing information carries the upstream neighbor is determined BGP It reaches the first MTU of IPv6 network routing;

[0070] MTU探测单元602,用于对接收的所述BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测; [0070] MTU detection unit 602, for receiving the BGP routing information carried in the BGP routing reaches a second MTU of the next hop corresponding to the IPv6 network detect;

[0071] 比较单元603,用于将比较所述第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; [0071] The comparing unit 603 for comparing the first size with the second MTU is detected MTU, the MTU value of the third smaller of the two as the determined arrival of BGP routing IPv6 network and stored;

[0072] 路由通告单元604,用于确定所述隧道中是否还存在下游BGP邻居,若存在,将所述第三MTU携带在到达该IPv6的BGP路由信息中并通告至所述下游BGP邻居。 [0072] The router advertisement unit 604 for determining whether there is downstream of the tunnel BGP peer, if present, the third MTU is carried in the BGP routing information reaching the advertisement to the IPv6 and the downstream BGP neighbor.

[0073] 进一步地,上述路由通告单元604,用于自定义BGP路由信息中的扩展团体属性,将自定义的扩展团体属性的类型字段设置为MTU ;将第三MTU的值封装在所述扩展团体属性的Value字段中。 [0073] Further, the route announcement unit 604 for customizing the BGP routing information in the extended community attribute, from the extended community attribute is defined for the type field set MTU; MTU value of the third package in the extension Value field community property.

[0074] 进一步地,本发明实施例提供的MTU的学习装置,还包括:MTU更新单元605 ; [0074] Further, the present invention MTU learning apparatus according to an embodiment, further comprising: updating unit MTU 605;

[0075] 相应地,比较单元603,还用于在BGP路由信息接收单元601当前接收的上游BGP邻居通告的BGP路由信息中的第一MTU与保存的第一MTU值不相等时,比较当前接收的所述BGP路由信息中的第一MTU与保存的第二MTU的大小确定两者中的较小值; When the first stored MTU value is not equal to the first MTU, comparing currently received [0075] Accordingly, the comparison unit 603 is further configured to BGP BGP peer BGP routing information advertised upstream receiving unit 601 receives the current information the first MTU BGP routing information to determine both the smaller size of the second MTU is stored;

[0076] MTU更新单元605,用于当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU ; [0076] MTU updating unit 605, and to a smaller value when the stored MTU is not equal to the third, the use of a smaller MTU value stored in the third update;

[0077] 路由通告单元604,还用于确定所述隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至所述下游BGP邻居。 [0077] The router advertisement unit 604, for determining whether there are further downstream from the BGP peer tunnel, if present, the third carries the MTU updated in downstream BGP BGP routing information reaching the advertisement to the IPv6 and neighbor.

[0078] 进一步地,本发明实施例提供的MTU的学习装置中的MTU探测单元602,还用于在路由通告单元604将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居的步骤之后,周期地对到达该IPv6网络的BGP路由下一跳的第二MTU进行探测; [0078] Further, the learning apparatus MTU according to an embodiment of the present invention, the MTU detection unit 602 is further configured to route announcement unit 604 in the third MTU is carried in the BGP routing information reaching the advertised IPv6 network and after step downstream to the BGP peer, to periodically reach the second IPv6 network routing BGP next hop MTU detect;

[0079] 比较单元603,还用于在MTU探测单元602当前探测到的第二MTU与保存的第二MTU不相等时,比较当前探测到的第二MTU与保存的第一MTU,确定两者中的较小值; [0079] The comparing unit 603 is further configured when the MTU of the current detection unit 602 to detect a second MTU of the second MTU stored unequal, comparing the current detected by the first MTU with the second MTU stored, determined both the smaller value;

[0080] MTU更新单元605,还用于当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU的值; [0080] MTU updating unit 605 is further configured with a smaller value when said third stored MTU not equal, using the updated value smaller MTU value stored in the third;

[0081] 路由通告单元604,还用于确定隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至隧道中的下游BGP邻居。 [0081] The router advertisement unit 604, further for determining whether there is a downstream tunnel BGP neighbor, if present, the third updated MTU is carried in the BGP routing information reaching the IPv6 and BGP neighbor advertisement to the downstream tunnel .

[0082] 进一步地,当本发明实施例提供的MTU的学习装置位于连接该IPv6网络的运营商边界设备中时,还可以包括: When [0082] Further, when the MTU learning device according to an embodiment of the present invention is positioned connected to the IPv6 network PE device may further comprise:

[0083] 获取单元606,用于获取所述运营商边界设备中与到达IPv6网络的路由对应的出接口的MTU ; [0083] The obtaining unit 606, configured to obtain the MTU carrier with the route to the edge device corresponding to the IPv6 network interface;

[0084] 相应地,路由通告单元604,还用于确定所述隧道中是否还存在下游BGP邻居,若存在,将获取到所述出接口的MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居。 [0084] Accordingly, route announcement unit 604 for determining whether there are further downstream from the BGP peer tunnel, if present, to obtain the MTU of the interface to the BGP routing information carried in the IPv6 network reach and BGP advertisement to the downstream neighbor.

[0085] 本发明实施例提供的MTU的学习装置,在具体实施时,可以通过设计下述功能模块实现:BGP模块、路由表管理模块、MTU自动探测模块,其中: [0085] MTU learning device according to an embodiment of the present invention, in the specific embodiment, a function may be achieved by designing the module: the BGP module, the routing table management module, MTU automatic detection module, wherein:

[0086] BGP模块用于通告BGP路由信息,优选和计算最优路由,更新路由对应的MTU的值以及向路由表安装更新路由表项。 [0086] means for BGP BGP routing information advertised, and preferably calculate the optimal route corresponding to the route update the MTU value, and install the update routing entries to the routing table.

[0087] 路由表管理模块用于管理路由表项,如确定路由对应的下一跳、出接口,以及出接口MTU的值,同时也负责向BGP模块通告路由更新的信息。 [0087] The routing table management module for managing the routing table entry, as determined corresponding to the next hop, an interface, and the values ​​on the interface MTU is also responsible for updating the routing information advertised to BGP module.

[0088] MTU自动探测模块用于自动探测到达某个地址的传输MTU值,并向BGP模块通告达到某个地址的MTU值。 [0088] MTU automatic detection means for automatically detecting the MTU of the transmission reaches an address, and an address reaches the MTU module BGP advertisement.

[0089] 为了实现利用上述学习到的MTU进行数据转发,在该装置中,还可以设置数据转发模块,用于利用学习到的MTU执行数据报文的分片和转发。 [0089] In order to achieve the above-described learned MTU for data forwarding, in the apparatus, data forwarding module may be provided, for utilizing learned MTU fragmentation packets and performs data forwarding.

[0090] 上述功能模块的划分和实现方式仅是一个具体实例,本发明实施例提供的MTU的学习装置并不限于上述的具体实现方式。 And partitioning implementation [0090] The functional modules is merely one specific example, MTU learning device according to an embodiment of the present invention is not limited to the specific implementations.

[0091] 本发明实施例还提供了一种路由设备,该路由设备包含本发明实施例提供的上述MTU学习装置。 Example [0091] The present invention further provides a routing device, the routing device including the MTU learning device according to an embodiment of the present invention.

[0092] 较佳地,本发明实施例提供的上述路由设备,在实际组网时,可以作为6PE应用场景中的运营商边界设备或者自治系统边界路由器。 [0092] Preferably, the above-described embodiment of the present invention, the routing device provided in the actual network, the edge device can be used as carriers or autonomous system border router 6PE application scenarios.

[0093] 本发明实施例提供的最大传输单元的学习方法、装置及路由设备,对于IPv4网络中形成的IPv6报文传输隧道中的每个运行BGP的路由设备,执行下述操作即:接收上游BGP邻居通告的到达IPv6网络的BGP路由信息;该BGP路由信息携带有该上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ;对接收的BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测;比较第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存;如果还存在下游BGP邻居,则将第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至下游BGP邻居,直至该隧道中的每个运行BGP的路由设备都学习到了到达该IPv6网络的BGP路由对应的MTU0本发明实施例在支持BGP协议的运营商边界设备和自治系统边界路由之间通过BGP路由传递MTU的值,使得传输IPv6 [0093] The learning method, the maximum transmission and routing equipment apparatus according to an embodiment of the present invention means, for each running BGP transmission tunnel IPv6 packets in IPv4 network routing devices are formed, i.e., performing the following: receiving an upstream BGP peer BGP routing information reaching the advertised IPv6 network; BGP routing information carries the MTU of the first upstream neighbor BGP reaches the determined IPv6 network routing; BGP routing information carried in the received BGP route reaches the IPv6 network the second MTU detect corresponding next hop; second comparing a first MTU size MTU is detected, the smaller of the two values ​​as the determined MTU third BGP route reaching the IPv6 network and stored; if there is also the downstream BGP neighbor, then the third MTU is carried in the BGP routing information to reach the IPv6 network and BGP announcement to the downstream neighbor, until the tunnel each running BGP routing devices have learned to reach the IPv6 BGP network MTU0 embodiment of the present invention according to the corresponding route passed by the MTU value BGP routes between PE device and an autonomous system border router support BGP protocol, so that the transmission IPv6 报文的隧道的终点即连接另一IPv6网络的运营商边界设备可以计算出到达目的IPv6网络的路由中各跳的MTU的最小值,并将其作为发送IPv6报文是否需要进行分片的依据,经过上述过程之后,在该隧道的终点收到发往该IPv6网络的IPv6报文时,将该报文的大小与自身保存的MTU的大小进行比较,决定是否需要分片,如果进行分片,分片后的报文的长度是到达该IPv6网络的路由中各跳MTU的最小值,因此,对于通过IPv4网络实现IPv6网络的互联互通的应用场景尤其是跨多个IPv4自治域实现IPv6网络的互联互通的应用场景来说,不论IPv4网络中传输IPv6报文的隧道需要跨越多少中间设备(例如P设备)或边界设备,任何中间设备或者边界设备,都不会因为IPv6报文长度的大小超出了该路由设备出接口的MTU的大小而丢弃该IPv6报文,从而避免了现有6PE技术出现的IPv6报文的传输受阻的 The end of the tunnel that is connected to the other packets of IPv6 network boundary device operator can calculate the minimum MTU route to the destination IPv6 network hops, and whether the packet needs to be fragmented in accordance with a transmission IPv6 when, after the above process, at the end of the tunnel receipt sent to the IPv6 network an IPv6 packet, the packet size and the size of their own to save the MTU are compared to determine whether to fragment, if fragmentation , the length of the packet is fragmented route to the IPv6 network hops MTU minimum, thus achieving interoperability scenarios IPv6 network through an IPv4 network, especially across multiple autonomous domain implementation IPv4 IPv6 network application scenarios for interoperability, regardless of how many intermediate IPv4 network transmission device (e.g. P device) or edge device requires a tunnel IPv6 packets across any intermediate device or edge device are not because of the size of the IPv6 packet length exceeds the MTU size of the routing device of an IPv6 interface discards the packet, thus avoiding the IPv6 packet transmission occurring prior art hindered 6PE 情况,并且在该隧道的终点对收到的IPv6报文进行分片操作后,该隧道中其他路由设备也不会再执行报文的分片操作,提高了IPv6报文在隧道中转发效率。 After the situation, and receiving an IPv6 packet slicing at the end of the tunnel, the tunnel will not be other routing devices slicing a packet, the IPv6 is improved in the efficiency of the tunnel.

[0094] 显然,本领域的技术人员可以对本发明进行各种改动和变型而不脱离本发明的精神和范围。 [0094] Obviously, those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. 这样,倘若本发明的这些修改和变型属于本发明权利要求及其等同技术的范围之内,则本发明也意图包含这些改动和变型在内。 Thus, if these modifications and variations of the present invention fall within the claims of the invention and the scope of equivalents thereof, the present invention intends to include these modifications and variations.

Claims (12)

1. 一种最大传输单兀MTU的学习方法,其特征在于,包括: 对于IPv4网络中形成的IPv6报文传输隧道中的每个运行边界网关协议BGP的路由设备执行下述操作: 接收IPv6报文传输隧道中上游边界网关协议BGP邻居通告的到达IPv6网络的BGP路由信息;所述BGP路由信息中携带有所述上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; 对接收的所述BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测; 比较所述第一MTU与探测到的第二MTU的大小,将两者中的较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; 确定所述隧道中是否还存在下游BGP邻居,若存在,将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居;若不存在,则结束MTU的学习过程。 A maximum transmission unit MTU Wu learning method comprising: for each run Border Gateway Protocol BGP transmission tunnel IPv6 packets in IPv4 network routing devices formed performing the following: receiving an IPv6 BGP routing information reaching the IPv6 tunnel packet transmission network border gateway protocol BGP upstream neighbor advertisement; BGP routing information carries the first MTU BGP peer routing the upstream reaches the determined IPv6 network; of the received said BGP routing information carried in the BGP routing reaches a second MTU of the next hop corresponding to the IPv6 network detect; comparing the first MTU with the second MTU size is detected, whichever is smaller, as determined a third arrival of BGP routing MTU IPv6 network and stored; if there is a downstream determining the BGP peer tunnel, if present, the third MTU is carried in the BGP routing reaches the IPv6 network advertisement information and to the downstream BGP neighbor; if not, then the end of the learning process of the MTU.
2.如权利要求I所述的方法,其特征在于,在到达IPv6网络的BGP路由信息中携带第一MTU或者第三MTU,通过下述方式实现: 自定义BGP路由信息中的扩展团体属性,将自定义的扩展团体属性的类型字段设置为MTU ;将第一MTU或第三MTU的值封装在所述扩展团体属性的Value字段中。 2. The method of claim I, wherein the first MTU or the third carries the MTU BGP routing information reaching the IPv6 network, implemented in the following manner: Custom extended community attribute in the BGP routing information, since the extended community attribute is defined for the type field set MTU; the first MTU or the third package MTU value of the extended community attribute in the value field.
3.如权利要求I所述的方法,其特征在于,所述上游BGP邻居为连接该IPv6网络的运营商边界设备时,所述第一MTU为所述运营商边界设备获取的所述运营商边界设备中与到达IPv6网络的路由对应的出接口的MTU。 3. The method according to claim I, characterized in that the upstream neighbor BGP PE device is connected to the IPv6 network, the first MTU is the operator of the PE device acquired the route to the edge device in the IPv6 network corresponding to the MTU of the interface.
4.如权利要求1-3任一项所述的方法,其特征在于,还包括: 保存所述第一MTU值与所述探测到的第二MTU的值。 4. The method of any one of claims 1-3, characterized in that, further comprising: saving the second value with the MTU value of the detected first MTU.
5.如权利要求4所述的方法,其特征在于,在当前接收的上游BGP邻居通告的BGP路由信息中的第一MTU与保存的第一MTU值不相等时,还包括: 比较当前接收的所述BGP路由信息中的第一MTU与保存的第二MTU的大小确定两者中的较小值,并当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU,确定所述隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至所述下游BGP邻居。 5. The method according to claim 4, wherein, when the first MTU value stored in the BGP routing information is not equal to the current received by the upstream neighbor BGP advertisement in a first MTU, further comprising: comparing the currently received the first MTU BGP routing information to determine both the smaller size of the second MTU is stored, and when the smaller MTU value stored in the third are not equal, the smaller value using third update the stored MTU, determine whether there are neighbor BGP downstream of the tunnel, if present, the third carries the MTU updated downstream neighbor BGP BGP routing information reaching the advertisement to the IPv6 and.
6.如权利要求4所述的方法,其特征在于,将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居的步骤之后,还包括: 周期地对到达该IPv6网络的BGP路由下一跳的第二MTU进行探测,并在当前探测到的第二MTU与保存的第二MTU不相等时,比较当前探测到的第二MTU与保存的第一MTU确定两者中的较小值;并当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU的值,确定所述隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至隧道中的下游BGP邻居。 After 6. The method according to claim 4, wherein the MTU is carried in the third arrival of BGP routing information of the IPv6 network and the step of BGP neighbor advertisement to downstream, further comprising: periodically for BGP route to the second IPv6 network MTU detect the next hop, and a second detected current when the second MTU MTU unequal, comparing the current detected by the first MTU with the second MTU storage saved determining the smaller value of the two; and, when said smaller MTU value stored in the third not equal, using the updated value of the third value smaller MTU saved, determining whether there is downstream of the tunnel BGP neighbor, if present, the third updated MTU is carried in the BGP routing information reaching the IPv6 and BGP neighbor advertisement to the downstream tunnel.
7. 一种最大传输单元MTU的学习装置,其特征在于,包括: BGP路由信息接收单元,用于接收IPv6报文传输隧道中上游边界网关协议BGP邻居通告的到达IPv6网络的BGP路由信息;所述BGP路由信息中携带有所述上游BGP邻居确定出的到达IPv6网络的路由的第一MTU ; MTU探测单元,用于对接收的所述BGP路由信息携带的到达该IPv6网络的BGP路由下一跳对应的第二MTU进行探测; 比较单元,用于将比较所述第一MTU与探测到的第二MTU的大小,将两者中较小值作为确定出的到达IPv6网络的BGP路由的第三MTU并保存; 路由通告单元,用于确定所述隧道中是否还存在下游BGP邻居,若存在,将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居。 A maximum transmission unit MTU of the learning apparatus comprising: a receiving unit BGP routing information, BGP routing information for reaching the IPv6 network receives a transmission tunnel IPv6 packets in an upstream Border Gateway Protocol BGP neighbor advertisement; the said BGP routing information carries the upstream neighbor BGP reaches a first determined route MTU IPv6 network; MTU detecting unit for BGP BGP routing said received routing information reaching the IPv6 network carrying the next corresponding to the second hop detect MTU; comparing means for comparing the first MTU with the second MTU size is detected, the smaller of the two values ​​is determined as the arrival of BGP routing IPv6 network and save the three MTU; route advertisement unit for determining whether there is downstream of the tunnel BGP peer, if present, the third MTU is carried in the BGP routing information reaching the IPv6 network and BGP advertisement to the downstream neighbor.
8.如权利要求7所述的装置,其特征在于,所述路由通告单元,进一步用于自定义BGP路由信息中的扩展团体属性,将自定义的扩展团体属性的类型字段设置为MTU ;将第三MTU的值封装在所述扩展团体属性的Value字段中。 8. The apparatus according to claim 7, wherein the RA unit is further configured to define the extended community attribute in the BGP routing information, from the extended community attribute set type field is defined as the MTU; the the third package MTU value in the extended community attribute value field.
9.如权利要求7或8所述的装置,其特征在于,还包括:MTU更新单元; 所述比较单元,还用于在BGP路由信息接收单元当前接收的上游BGP邻居通告的BGP路由信息中的第一MTU与保存的第一MTU值不相等时,比较当前接收的所述BGP路由信息中的第一MTU与保存的第二MTU的大小确定两者中的较小值; 所述MTU更新单元,用于当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU ; 所述路由通告单元,还用于确定所述隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至所述下游BGP邻居。 9. The apparatus of claim 7 or claim 8, characterized in that, further comprising: MTU updating unit; the comparison unit is further configured to BGP BGP peer BGP routing information advertised by the receiving unit upstream of the currently received information first MTU is not equal to the MTU value stored in the first, comparing the current first MTU BGP route information received in the smaller of the two is determined in the second MTU size saved; update the MTU means for, when said smaller value with the third stored MTU not equal, using the smaller MTU value stored in the third update; the RA unit is further for determining whether or not there is the tunnel BGP downstream neighbor, if present, the third updated MTU is carried in the BGP routing information reaching the advertisement to the IPv6 and the downstream BGP neighbor.
10.如权利要求7或8所述的装置,其特征在于,还包括:MTU更新单元; 所述MTU探测单元,还用于在路由通告单元将所述第三MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居的步骤之后,周期地对到达该IPv6网络的BGP路由下一跳的第二MTU进行探测; 所述比较单元,还用于在所述MTU探测单元当前探测到的第二MTU与保存的第二MTU不相等时,比较当前探测到的第二MTU与保存的第一MTU确定两者中的较小值; 所述MTU更新单元,用于当所述较小值与保存的第三MTU不相等时,使用所述较小值更新保存的第三MTU的值; 所述路由通告单元,还用于确定所述隧道中是否还存在下游BGP邻居,若存在,将更新后的第三MTU携带在到达该IPv6的BGP路由信息中并通告至隧道中的下游BGP邻居。 10. The apparatus of claim 7 or claim 8, characterized in that, further comprising: updating unit MTU; the MTU detection unit is further configured to route announcement unit MTU is carried in the third reaching the IPv6 network after BGP routing information and advertisement to said downstream step BGP neighbors periodically MTU second BGP next hop route to detect the IPv6 network; the comparison unit is further configured in the detection unit MTU the current detected when the second MTU is not equal to a second MTU stored, compares the current detected by the first MTU with the second MTU stored determining whichever is smaller; the MTU updating unit for, when the MTU is not equal to the third, the use of smaller value with said smaller value stored in the third updates the stored MTU value; the RA unit for determining whether there are further downstream from the BGP peer tunnel, If present, the third updated MTU is carried in the BGP routing information reaching the IPv6 and BGP neighbor advertisement to the downstream tunnel.
11.如权利要求7所述的装置,其特征在于,当所述装置位于连接该IPv6网络的运营商边界设备中时,还包括: 获取单元,用于获取所述运营商边界设备中与到达IPv6网络的路由对应的出接口的MTU ; 所述路由通告单元,还用于确定所述隧道中是否还存在下游BGP邻居,若存在,将获取到所述出接口的MTU携带在到达该IPv6网络的BGP路由信息中并通告至所述下游BGP邻居。 11. The apparatus according to claim 7, wherein, when the device is positioned connected to the IPv6 network Provider Edge device, further comprising: an acquisition unit configured to acquire the carrier reaches the boundary device with IPv6 network routing corresponding to the MTU of the interface; the RA unit for determining whether there are further downstream from the BGP peer tunnel, if present, out of the acquired MTU of the interface in the IPv6 network to carry BGP routing information and advertisement to said downstream BGP neighbor.
12. —种路由设备,其特征在于,包括如权利要求7〜11任一项所述的最大传输单元MTU的学习装置。 12. - kind of the routing device, characterized by comprising the MTU according to any one of claims 7~11 learning apparatus.
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