WO2017202106A1 - 基于串联结构分层光交叉连接的波带路由方法 - Google Patents

基于串联结构分层光交叉连接的波带路由方法 Download PDF

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WO2017202106A1
WO2017202106A1 PCT/CN2017/076222 CN2017076222W WO2017202106A1 WO 2017202106 A1 WO2017202106 A1 WO 2017202106A1 CN 2017076222 W CN2017076222 W CN 2017076222W WO 2017202106 A1 WO2017202106 A1 WO 2017202106A1
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path
band
connection request
optical
network node
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PCT/CN2017/076222
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English (en)
French (fr)
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陈彬
吴文龙
代明军
林晓辉
王晖
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深圳大学
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/62—Wavelength based

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  • the present invention relates to the field of optical communications, and more particularly to a waveband routing method based on a layered optical cross-connect in a series structure.
  • the technical problem to be solved by the present invention is to provide a waveband routing method based on a tandem structure layered optical cross-connection that can reduce the number of network optical switching ports for the above-mentioned drawbacks of the prior art.
  • the technical solution adopted by the present invention to solve the technical problem thereof is to construct a wave band routing method based on a tandem structure cross-connection of a series structure, comprising:
  • the sub-path is allocated by the connection request for the connection request based on the inclusion relationship of the band path and the optical path to route the connection request.
  • the optical path is allocated for the connection request, and the connection request can only be transmitted on one optical path of the band.
  • the optical path is allocated for the connection request, and the frequency slot on the optical path can only be used by one connection request.
  • the optical path is allocated for the connection request, and the number of frequency slots allocated on the optical path is equal to the number of the connection requests.
  • the optical path is allocated for the connection request to satisfy:
  • s, d represent the source node and the destination node of the connection request
  • k represents a path in the path pair between the nodes
  • b represents the band number
  • B represents the maximum number of bands in the fiber
  • w represents the frequency slot number
  • S Represents the total number of frequency slot resources in each fiber; Representing the tth connection request from the network node s to the network node d; in 1 when accepted by network node d, 0 otherwise; in Using the path p s, d, k the band b ⁇ [1, B] is 1, otherwise 0; p s, d, k represents the kth path from the network node s to the network node d; In the path p s, d, k is 1 through the optical fiber l, otherwise 0; Assigned to the frequency gap w ⁇ [1,S] And Is 1, otherwise 0; Express The number of requested frequency slots; M represents a large number of large values.
  • the band path is allocated for the connection request to satisfy that the two bands do not share the same frequency slot on the same link.
  • the band gap path for the connection request is satisfied that the end frequency slot number of the band is not less than the starting frequency slot number.
  • the frequency band number used for the connection request to satisfy the connection request is not less than the initial frequency slot number of the band and It will not be greater than the end slot number of band b.
  • the allocation of the band path for the connection request satisfies:
  • d represent the source node and the destination node of the connection request
  • k represents a path in the path pair between the nodes
  • b represents the band number
  • B represents the maximum number of bands in the fiber
  • C represents the intermediate frequency of each band.
  • the maximum number of gaps, w represents the specific frequency slot number; Representing the initial frequency slot number label representing the band b ⁇ [1, B] on the fiber l; Represents the terminating frequency slot label representing the band b ⁇ [1,B] on the fiber l; the fiber l fiber l Representing the tth connection request from the network node s to the network node d; in 1 when accepted by network node d, 0 otherwise; in Using the path p s, d, k the band b ⁇ [1, B] is 1, otherwise 0; p s, d, k represents the kth shortest path from the network node s to the network node d; In the path p s, d, k is 1 through the optical fiber l, otherwise 0; Assigned to the frequency gap w ⁇ [1,S] And Is 1, otherwise 0; M means large value; The path p s,d,k is used in the band path and the band b ⁇ [1,B] is
  • the band transmission path satisfies:
  • a method for implementing a wave-band routing method based on a tandem structure layered optical cross-connect of the present invention by assigning a connection request based on a distributed band path and an optical path, and assigning a connection request to the connection request based on an inclusion relationship of the band path and the optical path
  • the path can significantly save the number of switching ports, thereby reducing network costs.
  • FIG. 1 is a flow chart showing a method of wave band routing based on a tandem structure layered optical cross-connect according to the present invention
  • Figure 2 shows a schematic diagram of a series structure layered optical cross-connect
  • FIG. 3 is a schematic diagram showing a TS-HOXC-based band-switching elastic optical network
  • FIG. 4 shows an elastic optical network having a topology and connection request of WBS-EON as in 2;
  • Figure 5 shows a 6-node network topology
  • FIG. 6 is a diagram showing a wave band routing method based on a tandem structure layered optical cross-connection according to the present invention.
  • Figure 7 is a diagram showing the spectrum used by the WBS-EOC and the prior art based method for the number of CRs of each node pair using EON based on the banded routing method based on the tandem structure layered optical cross-connection of the present invention.
  • step S1 is a flow chart showing a method of wave band routing based on a tandem structure layered optical cross-connect according to the present invention.
  • step S1 a series structure layered optical cross-connection is respectively provided in a plurality of network nodes.
  • FIG. 2 shows a Tandem Structure Hierarchical Optical Cross-Connect (TS-HOXC).
  • TS-HOXC Tandem Structure Hierarchical Optical Cross-Connect
  • the optical path from the incoming fiber first reaches 1 ⁇ 2 WSS. If any of the service connections reach the destination node, they can be stripped from the band optical path and routed to the local optical receiver. The remaining band optical path will be sent to the Waveband Cross-Connect (WBXC) for band exchange. Finally, in the direction of the output fiber, the WSS carries a new service link that needs to be on the road. This separates the uplink and downlink functions of the service link from the band cross-connect, making the tandem structured layered cross-connect of the present invention more suitable for band switching. It can be noted that in TS-HOXC, a single optical channel cannot be switched from one band to another.
  • connection request can only be routed by selecting a band path. Therefore, if the path PA is a sub-path of the path PB, then all nodes at which the path PA is included will be included in the path PB. Therefore, choosing the best wavelength path becomes critical.
  • step S2 a band-switched elastic optical network based on a series structure layered optical cross-connect is constructed based on the plurality of network nodes.
  • FIG. 3 shows a TS-HOXC based Waveband Switched Elastic Optical Network (WBS-EON).
  • WBS-EON Waveband Switched Elastic Optical Network
  • a connection request is received from the first network node to the second network node, and a band path and an optical path are allocated for the connection request. Allocating an optical path for the connection request satisfies that the connection request can only be transmitted on one optical path of the band, and the frequency slot on the optical path can only be used by one connection request, and allocated on the optical path The number of frequency slots is equal to the number of connection requests the amount. Allocating a band path for the connection request satisfies that the two bands on the same link do not share the same frequency slot.
  • Allocating a band path for the connection request to satisfy the number of termination slots of the band is not less than the number of start slots, and the number of slots used for the connection request is not less than the number of start slots of the band and is not greater than the band b The number of termination slots.
  • step S4 a sub-path is allocated for the connection request based on the inclusion relationship of the band path and the optical path to route the connection request by a band.
  • multi-hop connection request CRs such as CR1 (A to D), CR2 (F to C), and CR3 (B to D).
  • CR1 A to D
  • CR2 F to C
  • CR3 B to D
  • the present invention can also implement transmission of single-hop, double-hop, and multi-hop connection requests.
  • a multi-hop connection request is taken as an example.
  • connection request CR The bandwidth of each connection request CR is assumed to be 2 frequency slots.
  • band path is set along paths A, F, B, E, C, and D.
  • three switching ports at nodes F, B, and C can be used, and the number of spectrum usages on the fiber connections (B, C) reaches 6.
  • the system can also be configured to use an EON with a layer of OXC.
  • EON a single OXC node will use the switch port for requesting CR through each connection of the node.
  • FIG 4 in addition to the optical signal access ports, four optical switching ports are required for nodes B, C, E, and F for elastic optical network path routing, ie, two switching ports are required for nodes F and E for Connection request CR1 requires a switch port for connection request CR2 at node B and a switch port for connection request CR3 at node C.
  • the spectrum usage reaches 4. As shown in this embodiment, fewer switch ports can be used using WBS-EON, however the cost may be to consume more spectrum.
  • the ILP formula is used to find the optimal solution for route, spectrum, and waveband assignment (RSBA).
  • This RSBA problem can be divided into two sub-problems.
  • the first sub-problem is that the route satisfies the elastic continuity of spectral continuity and spectral contiguity.
  • Spectral consistency constraints require that the optical path must use the same spectrum in each fiber through which it passes.
  • Spectral continuity constraints require that a continuous spectrum be assigned to the optical path. This is called Routing and Spectrum Allocation (RSA).
  • RSA Routing and Spectrum Allocation
  • the second problem is finding a good inclusion relationship in the band path and the light path.
  • the path of the band path needs to comply with the band consistency limit, which limits the frequency band used by the elastic path to be in the same band.
  • guard band can be used as part of the connection request CR, we do not consider it in the ILP formula for simplicity.
  • G(V, E) denotes a physical topology
  • V is a set of network nodes
  • E is a set of directed physical optical path paths.
  • p s,d,k denotes the kth shortest path from node s to node d in the physical topology.
  • S represents the total number of frequency slots in each fiber.
  • C represents the band size, which is defined as the maximum number of frequency slots in each band.
  • B represents the maximum number of bands in the fiber.
  • path p s,d,k is a subpath of p i,j,k' is 1, otherwise 0.
  • M stands for big value and is used to guarantee the priority optimization of a target when optimizing. Greater than the value of the secondary target.
  • band-path uses the path p s,d,k and the band b ⁇ [1,B] is 1, otherwise 0.
  • Z represents spectrum usage: the maximum number of frequency slots used in all fibers in the network.
  • the first term is the number of optical switching ports, of which only the optical switching ports used in the intermediate nodes are considered.
  • the second item is spectrum usage. Since we minimize the optical switching port as the main target, M in equation (1) takes a value much larger than Z, preferably 10 times or more of Z. Of course, in other embodiments of the present invention, other M values may be selected according to actual conditions.
  • Equation (2) is used to obtain spectrum usage. Equation (3) ensures that the connection request CR can only be transmitted on one path in the band. It should be noted that we do not consider the case where the CR is assigned to multiple paths.
  • Equation (4) ensures that the frequency gap w on the optical fiber 1 can only be used by one connection request CR.
  • Equation (5) ensures that the number of allocated frequency slots is equal to the number of connection requests requested. Spectral consistency is defined in equation (6).
  • Equation (7) ensures that the connection request CR can be assigned to the band-path.
  • the band size does not need to be the same throughout the band-path.
  • Equation (8) ensures the uniqueness of the band b on the optical fiber 1.
  • Equation (9) ensures the maximum band size limit.
  • Equation (10) ensures that the number of terminated frequency slots of the band is not less than the number of starting slots.
  • Equation (11) ensures that the two bands do not share the same frequency slot on the same link.
  • Equations (12) and (13) give the band consistency constraint. If the connection request CR uses the band b on the optical fiber 1, equation (12) ensures that the number of frequency slots used for the connection request is not less than the number of starting frequency slots of the band b. If the connection request CR uses the band b on the optical fiber 1, equation (13) ensures that the number of frequency slots used by the connection request is not greater than the number of termination slots of the band b.
  • FIG. 5 a 6-node, 9-path path network is shown in FIG. 5.
  • the band routing method based on the tandem structure layered optical cross-connection of the present invention is employed in the network shown in FIG. 5 to verify the result.
  • the method of the present invention can also be used in other larger networks. Those skilled in the art will be able to achieve such use based on the teachings of the present invention.
  • each optical path has one fiber in each direction.
  • the band width can be less than or equal to the band size.
  • B 4 bands can be accommodated.
  • the connection request between adjacent nodes is not considered, because for such a node, the band switching network cannot save the optical switching port.
  • Each node pair has the same number of connection requests (7) except for the neighbor node pair.
  • the bandwidth of each request is randomly selected as 1, 2 or 3 frequency slots.
  • K 5 shortest paths. Use the same path group for connection requests and band-paths.
  • Figure 6 plots the number of optical switching ports used by the number of CRs per node pair.
  • the number of optical switching ports used increases from 14 to 42.
  • the upward trend in the number of optical switching ports is much smaller than the increased value of C.
  • a method for implementing a wave-band routing method based on a tandem structure layered optical cross-connect of the present invention by assigning a connection request based on a distributed band path and an optical path, and assigning a connection request to the connection request based on an inclusion relationship of the band path and the optical path
  • the path can significantly save the number of switching ports, thereby reducing network costs.

Abstract

一种基于串联结构分层光交叉连接的波带路由方法，包括：S1、在多个网络节点中分别设置串联结构分层光交叉连接；S2、基于所述多个网络节点构造基于串联结构分层光交叉连接的波带切换弹性光网络；S3、接收从第一网络节点到第二网络节点的连接请求，为所述连接请求分配波带路径和光路路径；S4、基于所述波带路径和所述光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求。实施本发明的基于串联结构分层光交叉连接的波带路由方法，通过基于分配波带路径和光路路径给连接请求，并基于该波带路径和光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求，可以显著节省交换端口的数量，从而降低网络成本。

Description

基于串联结构分层光交叉连接的波带路由方法 技术领域
本发明涉及光通信领域，更具体地说，涉及一种基于串联结构分层光交叉连接的波带路由方法。
背景技术
现已观察到光传输技术的发展速度明显快于光交换技术。虽然在密集波分复用(Dense Wavelength Division Multiplexing,DWDM)系统中，光纤可以携带极大量的波长通道，但是目前可得的波长选择开关(Wavelength Selective Switch，WSS)的端口数至多只有20。因此，弹性光网络中的大规模光交叉连接((optical cross-connect,OCX)结构，通常是利用层叠波长选择开关来获得大的交换端口数目。然而，这一方面使得波长选择开关需求数目快速增加，另一方面信号的损耗也会随着层叠的数目随之增大。所以，降低网络光交换端口数目具有重要意义的。
发明内容
本发明要解决的技术问题在于，针对现有技术的上述缺陷，提供一种可以降低网络光交换端口数的基于串联结构分层光交叉连接的波带路由方法。
本发明解决其技术问题所采用的技术方案是：构造一种基于串联结构分层光交叉连接的波带路由方法，包括：
S1、在多个网络节点中分别设置串联结构分层光交叉连接；
S2、基于所述多个网络节点构造基于串联结构分层光交叉连接的波带切换弹性光网络；
S3、接收从第一网络节点到第二网络节点的连接请求，为所述连接请求分配波带路径和光路路径；
S4、基于所述波带路径和所述光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配光路路径满足所述连接请求只能在波带的一个光路路径上传输。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配光路路径满足在所述光路路径上的频隙仅能被一个连接请求使用。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配光路路径满足在所述光路路径上分配的频隙的数量等于所述连接请求的数量。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配光路路径满足：
Figure PCTCN2017076222-appb-000001
Figure PCTCN2017076222-appb-000002
Figure PCTCN2017076222-appb-000003
Figure PCTCN2017076222-appb-000004
其中，s,d分别表示连接请求的源节点和目的节点，k表示节点对间路径集中的一条路径，b表示波带序号，B表示光纤中波带的最大数量，w表示频隙序号，S表示在每个光纤中的频隙资源的总数；
Figure PCTCN2017076222-appb-000005
表示从网络节点s到网络节点d的第t连接请求；
Figure PCTCN2017076222-appb-000006
在
Figure PCTCN2017076222-appb-000007
被网络节点d接受时为1，否则为0；
Figure PCTCN2017076222-appb-000008
在
Figure PCTCN2017076222-appb-000009
使用路径ps,d,k上的波带b∈[1,B]为1，否则为0；ps,d,k表示从网络节点s到网络节点d的第k条路径；
Figure PCTCN2017076222-appb-000010
在路径ps,d,k经过光纤l是为1，否则为0；
Figure PCTCN2017076222-appb-000011
在频隙w∈[1,S]分配给
Figure PCTCN2017076222-appb-000012
且
Figure PCTCN2017076222-appb-000013
为1，否则为0；
Figure PCTCN2017076222-appb-000014
表示
Figure PCTCN2017076222-appb-000015
请求的频隙的数量；M表示一个很大的数大值。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配波带路径满足在相同的链路两个波带并不共享相同的频隙。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配波带路径满足波带的终止频隙序号不小于起始频隙序号。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配波带路径满足连接请求使用的频隙序号不会小于波带的起始频隙序号且不会大于波带b的终止频隙序号。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，为所述连接请求分配波带路径满足：
Figure PCTCN2017076222-appb-000016
Figure PCTCN2017076222-appb-000017
Figure PCTCN2017076222-appb-000018
Figure PCTCN2017076222-appb-000019
Figure PCTCN2017076222-appb-000020
Figure PCTCN2017076222-appb-000021
其中，s,d分别表示连接请求的源节点和目的节点，k表示节点对间路径集中的一条路径，b表示波带序号，B表示光纤中波带的最大数量，C表示每个波带中频隙的最大数量，w表示具体的频隙序号；
Figure PCTCN2017076222-appb-000022
表示代表在光纤l上波 带b∈[1,B]的起始频隙数标号；
Figure PCTCN2017076222-appb-000023
表示代表在光纤l上波带b∈[1,B]的终止频隙标号；光纤l光纤l
Figure PCTCN2017076222-appb-000024
表示从网络节点s到网络节点d的第t连接请求；
Figure PCTCN2017076222-appb-000025
在
Figure PCTCN2017076222-appb-000026
被网络节点d接受时为1，否则为0；
Figure PCTCN2017076222-appb-000027
在
Figure PCTCN2017076222-appb-000028
使用路径ps,d,k上的波带b∈[1,B]为1，否则为0；ps,d,k表示从网络节点s到网络节点d的第k条最短路径；
Figure PCTCN2017076222-appb-000029
在路径ps,d,k经过光纤l是为1，否则为0；
Figure PCTCN2017076222-appb-000030
在频隙w∈[1,S]分配给
Figure PCTCN2017076222-appb-000031
且
Figure PCTCN2017076222-appb-000032
为1，否则为0；M表示大值；
Figure PCTCN2017076222-appb-000033
在波带路径使用路径ps,d,k且波带b∈[1,B]为1，否则为0。
在本发明所述的基于串联结构分层光交叉连接的波带路由方法中，在所述步骤S4中，所述波带传输通路满足：
Figure PCTCN2017076222-appb-000034
实施本发明的基于串联结构分层光交叉连接的波带路由方法，通过基于分配波带路径和光路路径给连接请求，并基于该波带路径和光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求，可以显著节省交换端口的数量，从而降低网络成本。
附图说明
下面将结合附图及实施例对本发明作进一步说明，附图中：
图1示出了根据本发明的基于串联结构分层光交叉连接的波带路由方法的流程示意图；
图2示出了串联结构分层光交叉连接的逻辑示意图；
图3示出了基于TS-HOXC的波带切换弹性光网络的逻辑示意图；
图4示出了具有如2中的WBS-EON的拓扑和连接请求的弹性光网络；
图5示出了6-节点网络拓扑；
图6绘制了基于本发明的基于串联结构分层光交叉连接的波带路由方法 采用WBS-EOC和基于现有技术的方法采用EON的每个节点对的CR数量使用的光交换端口的数量；
图7绘制了基于本发明的基于串联结构分层光交叉连接的波带路由方法采用WBS-EOC和基于现有技术的方法采用EON的每个节点对的CR数量使用的频谱。
具体实施方式
图1示出了根据本发明的基于串联结构分层光交叉连接的波带路由方法的流程示意图。在步骤S1中，在多个网络节点中分别设置串联结构分层光交叉连接。
图2示出了串联结构分层光交叉连接(Tandem Structure Hierarchical Optical Cross-Connect，TS-HOXC)。其中来自入路光纤的光路首先到达1×2WSS。如果任何业务连接到达目的节点，可以将其从波带光路中剥离并且下路到本地光接收器。剩余的波带光路将送到波带交叉连接(Waveband Cross-Connect，WBXC)进行波带交换。最后在输出光纤方向上通过WSS携带上需要上路的新的业务链接。这将业务链接的上路和下路功能从波带交叉连接中分离出来，使得本发明的串联结构分层光交叉连接更适合用于波带交换。可以注意到，在TS-HOXC中，单个光通道不能从一个波带切换到另一个波带。这意味着连接请求只能选择一条波带路径进行路由。因此，如果路径PA是路径PB的子路径，那么路径PA在的全部节点都将包括在路径PB中。因此，选择最佳波带路径变得至关重要。
在步骤S2中，基于所述多个网络节点构造基于串联结构分层光交叉连接的波带切换弹性光网络。图3示出了基于TS-HOXC的波带切换弹性光网络(Waveband Switched Elastic Optical Network，WBS-EON)。
在步骤S3中，接收从第一网络节点到第二网络节点的连接请求，为所述连接请求分配波带路径和光路路径。为所述连接请求分配光路路径满足所述连接请求只能在波带的一个光路路径上传输，在所述光路路径上的频隙仅能被一个连接请求使用，在所述光路路径上分配的频隙的数量等于所述连接请求的数 量。为所述连接请求分配波带路径满足在相同的链路两个波带并不共享相同的频隙。为所述连接请求分配波带路径满足波带的终止频隙数量不小于起始频隙数量，连接请求使用的频隙数量不会小于波带的起始频隙数量且不会大于波带b的终止频隙数量。
在步骤S4中基于所述波带路径和所述光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求。
下面结合图3的基于TS-HOXC的波带切换弹性光网络以及图4的具有如图3中的WBS-EON的拓扑和连接请求CR的EON，对本发明的方法说明如下。
需要注意的是，如果波带交换是位于两个相邻的节点，那么是不能为连接请求节省交换端口。因此，我们仅考虑多跳连接请求CR，例如CR1(A到D)、CR2(F到C)和CR3(B到D)。当然，在实际操作中，本发明也可以实现单跳，双跳以及多跳连接请求的传输。在此，只是为了说明的方便，仅采用多跳连接请求为例。
每个连接请求CR的带宽假定为2频隙。当全部的连接请求CR沿着该波带路径路由时，波带路径沿着路径A、F、B、E、C和D设置。除了光信号上下路端口外，可以使用在节点F、B和C的三个交换端口，且在光纤连接(B、C)上的频谱使用数达到6。
该系统也可以配置成使用具有一层OXC的EON。在该EON中，单个的OXC节点将使用交换端口用于通过该节点的每个连接请求CR。在图4中，除了光信号上下路端口外，其在节点B、C、E和F需要四个光学交换端口用于弹性光网络路径路由，即在节点F和E需要两个交换端口用于连接请求CR1，在节点B需要一个交换端口用于连接请求CR2，在节点C需要一个交换端口用于连接请求CR3。频谱使用达到4。如该实施例所示，使用WBS-EON可以使用更少的交换端口，然而代价可能是消耗更多的频谱。
下面，我们采用整数线性规划(Integer Linear Programming,ILP)公式比较WBS-EON和EON之间的优化路径解决方案，进而对本发明的基于串联结构分层光交叉连接的波带路由方法的操作原理，具体步骤以及其有益效果说明如 下。
基于上述子路径关系采用ILP公式为路由、频谱和波带分配(route,spectrum,and waveband assignment，RSBA)寻找最优解。该RSBA问题可以分成两个子问题。第一个子问题是路由满足频谱一致性(spectral continuity)和频谱连续性(spectral contiguity)的弹性光路。频谱一致性约束要求光路在其传输通过的各个光纤中必须使用相同的频谱。频谱连续性约束要求将连续的频谱分配给光路。这叫做路由和频谱分配(RSA)问题。第二个问题是在波带路径和光路中找到良好的包含关系。波带路径路由需要符合波带一致性限制，其限制弹性光路使用的频隙位于相同的波带内。因为保护波带(guard band)可以作为连接请求CR的一部分，为了简化，我们在ILP公式中不对其进行考虑。在网络中，我们使用i和j表示波带-路径的源节点和目的节点，且采用s和d表示连接请求CR的源节点和目的节点。
--------------------------------------------------------------
给定参数如下：
G(V,E)表示物理拓扑，V是网络节点集合，且E是定向物理光路路径集合。
Figure PCTCN2017076222-appb-000035
表示从节点s到节点d的第t个连接请求。
Figure PCTCN2017076222-appb-000036
表示CR
Figure PCTCN2017076222-appb-000037
请求的频隙的数量。
ps,d,k表示在物理拓扑中从节点s到节点d的第k条最短路径。
S表示在每个光纤中的频隙的总数。
C表示波带大小，其定义成在每个波带中频隙的最大数量。
B表示光纤中波带的最大数量。
Figure PCTCN2017076222-appb-000038
如果路径ps,d,k经过光纤l是为1，否则为0。
Figure PCTCN2017076222-appb-000039
如果路径ps,d,k是pi,j,k’的子路径为1，否则为0。
M表示大值(big value)，用来保证优化时对某个目标的优先优化，该值 大于次目标的值。
l表示光纤。
决策变量：
Figure PCTCN2017076222-appb-000040
如果CR
Figure PCTCN2017076222-appb-000041
被接受为1，否则为0。
Figure PCTCN2017076222-appb-000042
如果频隙w∈[1,S]分配给
Figure PCTCN2017076222-appb-000043
且
Figure PCTCN2017076222-appb-000044
为1，否则为0。
Figure PCTCN2017076222-appb-000045
表示代表在光纤l上波带b∈[1,B]的起始频隙数的整数变量。
Figure PCTCN2017076222-appb-000046
表示代表在光纤l上波带b∈[1,B]的终止频隙数的整数变量。
Figure PCTCN2017076222-appb-000047
如果CR
Figure PCTCN2017076222-appb-000048
使用路径ps,d,k上的波带b∈[1,B]为1，否则为0。
Figure PCTCN2017076222-appb-000049
如果波带-路径使用路径ps,d,k且波带b∈[1,B]为1，否则为0。
Z表示频谱使用：在网路中全部光纤中使用的频隙的最大标号。
在WBS-EON中的RSBA问题
目标函数：
Figure PCTCN2017076222-appb-000050
在等式(1)中，第一项是光交换端口的数量，其中仅考虑在中间节点中使用的光交换端口。第二项是频谱使用。因为我们将最小化光交换端口作为主要目标，所以等式(1)中的M取远大于Z的值，优选为Z的10倍以上的值。当然，在本发明的其他实施例中，也可以根据实际情况，选用其他M值。
约束式：
Figure PCTCN2017076222-appb-000051
Figure PCTCN2017076222-appb-000052
等式(2)用于获得频谱使用。等式(3)保证连接请求CR仅能在波带中的一个路径上传输。应注意，在此我们不考虑CR被分配到多个路径的情况。
Figure PCTCN2017076222-appb-000053
Figure PCTCN2017076222-appb-000054
Figure PCTCN2017076222-appb-000055
等式(4)确保在光纤l上的频隙w仅仅能够被一个连接请求CR使用。等式(5)确保分配的频隙的数量等于请求的连接请求数量。在等式(6)中定义了频谱一致性。
Figure PCTCN2017076222-appb-000056
等式(7)确保在连接请求CR可以被分配到波带-路径。在此，在整个波带-路径中，波带大小不需要相同。
Figure PCTCN2017076222-appb-000057
等式(8)确保在光纤l上的波带b的独特性(uniqueness)。
Figure PCTCN2017076222-appb-000058
Figure PCTCN2017076222-appb-000059
Figure PCTCN2017076222-appb-000060
等式(9)确保最大波带大小限制。等式(10)确保波带的终止频隙数量不小于起始频隙数量。等式(11)确保在相同的链路两个波带并不共享相同的频隙。
Figure PCTCN2017076222-appb-000061
Figure PCTCN2017076222-appb-000062
等式(12)和(13)给出了波带一致性约束。如果连接请求CR使用光纤l上的波带b，等式(12)确保连接请求使用的频隙数量不会小于波带b的起始频隙数量。如果连接请求CR使用光纤l上的波带b，等式(13)确保连接请求使用的频隙数量不会大于波带b的终止频隙数量。
在此，在图5中示出了6-节点、9-光路路径网络。下面在图5所示网络中采用本发明的基于串联结构分层光交叉连接的波带路由方法，以验证其结果。当然，本发明的方法也可在其他更大的网络中进行使用。基于本发明的教导，本领域技术人员能够实现这样的使用。
假设每个光路路径在每个方向具有一个光纤。每个光纤有32个频隙。在此，我们选择四个波带的大小(C)，如8、16、24、32个频隙。值得注意的是，波带宽度可以小于或等于波带大小。在每一个光纤中，可以容纳至多B＝4个波带。不考虑相邻节点之间的连接请求，因为对于这样的节点，波带交换网络不能节省光交换端口。除了邻居节点对之外，每个节点对具有相同数量的连接请求(7)。每个请求的带宽是随机选择为1、2或3个频隙。对于每个节点对，首先计算K＝5个最短路径。对于连接请求和波带-路径，使用相同的路径组。
图6绘制了每个节点对的CR数量使用的光交换端口的数量。在使用一个层的OXC中，随着CR数量的增加，使用的光交换端口的数量从14增加到42。在具有TS-HOXC的网络中，光交换端口的数量的上升趋势大大小于C的增加值。在具有TS-HOXC的网络中，当C＝8时，光交换端口的数量增至10-16。因为波带大小越来越大，波带交换端口可以分组光路的增加数量。应注意，对于C＝32，当流量负载增加时，交换端口的数量总是等于9。对于T＝3，使用TS-HOXC的网络与一层OXC相比，可以节省78％的交换端口。
图7绘制了每个节点对的CR数量使用的频谱。可以看到，对于两个网络，在流量负载增加时，频谱使用增加。对于T＝1和T＝2，WBS-EON和EON (无波带交换)具有相同的频谱使用。当T＝3时，C＝8的WBS-EON和EON频谱使用相等且等于13。C＝16、24和32的WBS-EON的频谱使用相同且等于14。值得注意的是，频谱使用在等式(1)中是次要优化目标。因此，如果必要的话，网络可以牺牲一些频谱资源，用于节省交换端口。
比较图5和图6可知，WBS-EON可以显著节省交换端口的数量，并且，该节省效果随着连接请求数量的增加和最大波带的增加而变得更加显著。当最大波带大小等于光纤容量，网络可以节省最大数量的光交换端口。同时，为了节省光交换端口所付出的成本并不多。当C＝32，WBS-EON的频谱使用仅略高于EON。总之，因此基于WBS-EON的TS-HOXC可以大大减少光交换端口，并且达到几乎相同的路由性能。
实施本发明的基于串联结构分层光交叉连接的波带路由方法，通过基于分配波带路径和光路路径给连接请求，并基于该波带路径和光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求，可以显著节省交换端口的数量，从而降低网络成本。
虽然本发明是通过具体实施例进行说明的，本领域技术人员应当明白，在不脱离本发明范围的情况下，还可以对本发明进行各种变换及等同替代。因此，本发明不局限于所公开的具体实施例，而应当包括落入本发明权利要求范围内的全部实施方式。

Claims (10)

  1. 一种基于串联结构分层光交叉连接的波带路由方法，其特征在于，包括：
    S1、在多个网络节点中分别设置串联结构分层光交叉连接；
    S2、基于所述多个网络节点构造基于串联结构分层光交叉连接的波带切换弹性光网络；
    S3、接收从第一网络节点到第二网络节点的连接请求，为所述连接请求分配波带路径和光路路径；
    S4、基于所述波带路径和所述光路路径的包含关系为所述连接请求分配子路径以波带路由所述连接请求。
  2. 根据权利要求1所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配光路路径满足在所述光路路径上只能在一条波带传输通道传输。
  3. 根据权利要求2所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配光路路径满足在所述光路路径上的频隙仅能被一个连接请求使用。
  4. 根据权利要求3所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配光路路径满足在所述光路路径上分配的频隙的数量等于所述连接请求的频隙资源数量。
  5. 根据权利要求3所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配光路路径满足：
    Figure PCTCN2017076222-appb-100001
    Figure PCTCN2017076222-appb-100002
    Figure PCTCN2017076222-appb-100003
    Figure PCTCN2017076222-appb-100004
    其中，s,d分别表示连接请求的源节点和目的节点，k表示节点对间路径集中的一条路径，b表示波带序号，B表示光纤中波带的最大数量，w表示频隙序号，S表示在每个光纤中的频隙资源的总数；
    Figure PCTCN2017076222-appb-100005
    表示从网络节点s到网络节点d的第t连接请求；
    Figure PCTCN2017076222-appb-100006
    在
    Figure PCTCN2017076222-appb-100007
    被网络节点d接受时为1，否则为0；
    Figure PCTCN2017076222-appb-100008
    在
    Figure PCTCN2017076222-appb-100009
    使用路径ps,d,k上的波带b∈[1,B]为1，否则为0；ps,d,k表示从网络节点s到网络节点d的第k条路径；
    Figure PCTCN2017076222-appb-100010
    在路径ps,d,k经过光纤l是为1，否则为0；
    Figure PCTCN2017076222-appb-100011
    在频隙w∈[1,S]分配给
    Figure PCTCN2017076222-appb-100012
    且
    Figure PCTCN2017076222-appb-100013
    为1，否则为0；
    Figure PCTCN2017076222-appb-100014
    表示
    Figure PCTCN2017076222-appb-100015
    请求的频隙的数量；M表示大值。
  6. 根据权利要求1-5中任意一项权利要求所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配波带路径满足在相同的链路两个波带并不共享相同的频隙。
  7. 根据权利要求6所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配波带路径满足波带的终止频隙序号不小于起始频隙序号。
  8. 根据权利要求7所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配波带路径满足连接请求使用的频隙序号不会小于波带的起始频隙序号且不会大于波带b的终止频隙序号。
  9. 根据权利要求8所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，为所述连接请求分配波带路径满足：
    Figure PCTCN2017076222-appb-100016
    Figure PCTCN2017076222-appb-100017
    Figure PCTCN2017076222-appb-100018
    Figure PCTCN2017076222-appb-100019
    Figure PCTCN2017076222-appb-100020
    Figure PCTCN2017076222-appb-100021
    其中，s,d分别表示连接请求的源节点和目的节点，k表示节点对间路径集中的一条路径，b表示波带序号，B表示光纤中波带的最大数量，C表示每个波带中频隙的最大数量，w表示具体的频隙序号；
    Figure PCTCN2017076222-appb-100022
    表示代表在光纤l上波带b∈[1,B]的起始频隙数标号；
    Figure PCTCN2017076222-appb-100023
    表示代表在光纤l上波带b∈[1,B]的终止频隙标号；
    Figure PCTCN2017076222-appb-100024
    表示从网络节点s到网络节点d的第t连接请求；
    Figure PCTCN2017076222-appb-100025
    在
    Figure PCTCN2017076222-appb-100026
    被网络节点d接受时为1，否则为0；
    Figure PCTCN2017076222-appb-100027
    在
    Figure PCTCN2017076222-appb-100028
    使用路径ps,d,k上的波带b∈[1,B]为1，否则为0；ps,d,k表示从网络节点s到网络节点d的第k条最短路径；
    Figure PCTCN2017076222-appb-100029
    在路径ps,d,k经过光纤l是为1，否则为0；
    Figure PCTCN2017076222-appb-100030
    在频隙w∈[1,S]分配给
    Figure PCTCN2017076222-appb-100031
    且
    Figure PCTCN2017076222-appb-100032
    为1，否则为0；M表示大值；
    Figure PCTCN2017076222-appb-100033
    在波带路径使用路径ps,d,k且波带b∈[1,B]为1，否则为0。
  10. 根据权利要求9所述的基于串联结构分层光交叉连接的波带路由方法，其特征在于，在所述步骤S4中，所述波带传输通路满足：
    Figure PCTCN2017076222-appb-100034
    其中，
    Figure PCTCN2017076222-appb-100035
    在路径ps,d,k是pi,j,k’的子路径时为1，否则为0。
PCT/CN2017/076222 2016-05-27 2017-03-10 基于串联结构分层光交叉连接的波带路由方法 WO2017202106A1 (zh)

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