CN101674500A - Transmission method of mixed light exchanging network - Google Patents

Abstract

The invention belongs to a data transmission method in a light network communication technique. In the transmission method, an OCS and OBS mixed switching network is firstly set, wherein both the OBSand OCS modules in the nodes of the network have the OBS and OCS switching ability. The transmission method comprises the following steps: when the network is under normal operation, transmitting alldata streams by an OCS optical path; when the data amount suddenly increases resulting in optical path overload, transmitting the overflowed data stream through the OBS; and transmitting the checked data to a destination node through the OBS optical path in the failure of the OCS optical path in the network. Accordingly, the invention has the characteristics of high network resource utilization ratio and transmission efficiency, effectively-improved safety and reliability of data transmission, greatly declined packet loss rate, low operating cost of the network, and the like. The invention overcomes the defects of low transmission efficiency, high packet loss rate and resource vacancy rate, large waste, higher operating cost, and the like caused by the condition that the data can be transmitted only in a predetermined way, and an optical path for devices is needed in an area where a fault occurs in the background art.

Description

A kind of transmission method of hybrid optical switching network

Technical field

The invention belongs to technical field of optical network communication, particularly a kind of transmission method that relates to the hybrid optical switching network of optical circuit exchange (OCS) and light burst-switched (OBS).

Background technology

Initial optical-fiber network passes through the interconnected composition of optical fiber link between points, is generally used for making up Backbone Transport Network.Light signal transmits on a wavelength channel of optical fiber, and each network node all will be converted to the signal of telecommunication with light signal and handle, and then is converted to light signal so that continue transmission.Because the degree of communication of backbone network topological structure is very low, about 70% is to transmit data in the data to be transmitted, and promptly data need could arrive destination node through a plurality of network nodes.Because the processing speed in electric territory is well below the transmission speed in light territory, therefore, electric territory disposal ability is the bottleneck of optical-fiber network.At this problem, researchers have proposed some solutions, produced WDM (Wavelength Division Multiplex wavelength division multiplexing) optical-fiber network and corresponding switching technology-optical circuit exchange (Optical Circuit Switching, OCS), light packet switching (Optical Packet Switching, OPS) and the light burst-switched (Optical Burst Switching, OBS).

Optical circuit exchange (OCS) and traditional circuit switching are similar, need to set up before the data transmission light path from source to destination (lightpath, by on a plurality of physical fiber links the wavelength channel of same wavelength form); Light path can realize the end-to-end transparent transmission of Business Stream in the light territory after setting up; Yet when Business Stream presents highly when sudden, consider expenses such as light path foundation, maintenance and dismounting, dynamically set up and remove light path fully according to service request and just be difficult to realize.Light packet switching (OPS) is similar with traditional packet network (exchange), adopts the storage retransmission technique, because it can the statistic multiplexing wavelength resource, thereby is fit to carry burst service; It is very high that yet OPS sun adjuster spare requires, and its practical application foreground is limited by the optical device technology, in a short time also can't commercial rollout.Light burst-switched (OBS) is the compromise of OCS, two kinds of exchanged forms of OPS; The method of its transmission is: when data arrive the OBS network node according to destination address and other attributes (as service quality QoS, Qualityof Service) is classified, similar a plurality of packets are pooled burst packets (Burst), generate an independently control grouping simultaneously, head (Burst Head Packet promptly happens suddenly, BHP), burst head (BHP) enters control channel prior to burst packets (Burst), at each OBS network node place of approach is corresponding Burst reservation wavelength resource (transmission channel), makes Burst can realize full light path exchange; Yet the key issue that OBS exists is not resolve the problem of reservation conflict, thereby the phenomenon (accident) that burst packets (Burst) is dropped in the transport process can't be avoided and effective the reduction.

Defective that exists at above-mentioned single light exchanged form and IP operation high sudden, traffic carrying capacity is big or small unpredictable, characteristics such as traffic carrying capacity duration frequent variations, people fully utilize different light switching technologies.Because optical packet switching technique is difficult to realize under existing technical conditions, therefore, generally is that optical circuit exchange and OBS are combined, form the mixed light switching technology; This mixed optical network switching technology mainly comprises master-slave type and parallel type.The master-slave type network is made of client layer (Client) and service layer (Server); Wherein, Client layer employing OBS/OPS exchange, the Server layer adopts the OCS exchange, burst packets/be grouped in the exchange of Client layer, by the light path arrival destination node of Server layer; The master-slave type network still belongs to the OBS exchange in essence.The parallel type network is by the parallel OBS that exists and OCS is two-layer forms, and each node constitutes by OBS module and OCS module in the network, and two kinds of switch modes are relatively independent, shared network resource; According to its duration, quality of service requirement is divided into short Business Stream (burst service stream) and long Business Stream (general traffics) to network edge node with the IP grouping, uses OBS to transmit short Business Stream, and OCS transmits long Business Stream, and professional load mode no longer changes.This parallel type network fails it is organically combined, works in coordination with transmission only with OCS, OBS simple superposition, and the difficulty of IP grouping is bigger in addition, so this mixed optical network exchanged form also is difficult to effectively reduce packet loss.

In addition, the professional fail safe that transmits is another importance that the optical-fiber network transmission should solve.The statistics of U.S. FCC shows, breaks down if a transmission capacity is the optical fiber of Tb/s, will influence 1,200 ten thousand pairs of telephone services at least.Therefore, when network broke down, how guaranteeing to make affected business to be continued smooth transmission also was vital task in the optical-fiber network transmission.The existing protective measure that is used to tackle network failure is to set up special-purpose standby light path, promptly at the standby light path of the default protectiveness in each interval that may break down, and the business of being obstructed in order to shunting; Promptly at the default standby light path in each interval that may break down, in order to the be obstructed business of (also claiming " inefficacy ") of transmission; Could share the standby light path two big classes that standby light path is divided into special-purpose standby light path again and shares according to standby resources; According to the mode of implementing protection, protection is divided into link protection, sectionalised protection and path protection again.

Protection based on link is meant when setting up each bar working light path, at the default standby light path of every link of this light path process, when network generation link failure, former plan changes by this standby optic path through the data flow on this link working light path, proceeds thereby walk around the fault point;

Sectionalised protection is meant working light path is divided into plurality of sections, then each section is set up standby light path respectively, and when certain section working light path broke down, data carried by data can be switched on the corresponding standby light path and transmit on the working light path section that breaks down.

Protection based on path is meant when setting up working light path, at same source order node to setting up a standby light path.

Thereby above-mentioned hybrid optical switching network exists can only carry out the very flexible of transmission by predefined load mode; Aspect the fail safe of business transmission; standby light path at the default protectiveness in each interval that may break down (section); these standby light paths all are in idle state when the network free barrier takes place; thereby the efficiency of transmission that has network is lower, the processing method of reply network failure falls behind; the vacancy rate height of Internet resources, waste are big, the more high defective of the operating cost of packet loss and network.

Summary of the invention

The objective of the invention is on basis of background technology, improve the transmission method of a kind of hybrid optical switching network of design, efficiency of transmission with effective raising utilization rate of network resource and hybrid optical switching network, guarantee the professional fail safe that transmits, effectively reduce the purposes such as operating cost of packet loss and network.

Solution of the present invention is the defective that exists at background technology, former fixing employing OBS is transmitted short Business Stream (burst service stream), OCS transmits the transmission means of long Business Stream (general traffics), change into: when the network operate as normal, total data (business) stream transmits by OCS light path (layer); When the sudden growth of data (business) amount causes the light path overload, send its overflow data (business) that surpasses OCS light path bearing capacity stream by OBS again; And when network breaks down, when one or more OCS light path fault occurring,, the data (business) of being obstructed are continued to be sent to destination node also by this OBS light path (layer); The OBS of each intranodal of network and OCS module all have the exchange capacity of OBS and OCS in this solution; The present invention promptly realizes its purpose with this.Thereby the inventive method comprises:

A. set up hybrid optical switching network:

At first, set up light path, form the OCS transport layer according to data (business) amounts, link wavelength available information, simultaneously for homology order node not to definite OCS route and set up corresponding routing table (OCS routing table); And then the OBS transport layer is set, the wavelength available of every link of configuration OBS layer, for homology order node not to definite OBS route, and set up corresponding routing table (OBS routing table); When each link wavelength available of configuration OBS layer, every link all uses a wavelength channel as control channel, is used for transmitting the burst head, and all the other wavelength channels are used to transmit burst packets; Each node still is made up of OBS module and OCS module in the network;

B. data (business) transmit flow process, comprising:

Step 1.0. selects the OCS light path: according to the order address, source and the OCS routing table that enter network packet (packet is the IP block form), determine OCS transmission light path;

Step 1.1. judges whether light path is unimpeded: at the light path of being selected by step 1.0., take situation according to the real time information of light path detection module in the network node and light path buffer memory and judge whether light path is unimpeded, if not smooth, then change step 2.0 processing through 1.1.1 or 1.1.2; Otherwise change step 1.2;

Step 1.2. packet sends: will put into the light path buffer memory by the data that step 1.1 enters, and the recording beam path buffer memory takies situation, then the packet of the team in the buffer memory is sent to step 3.0 through the OCS light path;

Step 2.0. burst packets/first-born one-tenth happens suddenly: when by step 1.1 through 1.1.1 or 1.1.2 enter overflow data in buffer reach converge threshold value after, it converged be burst packets, generate corresponding burst head simultaneously, change step 2.1 then;

Step 2.1. determines that OBS transmits light path: after determining that according to happen suddenly a destination node information of record and OBS routing table OBS transmits light path, change step 2.2 transmission;

Step 2.2. sends burst head and burst packets: at first will be by step 2.1 or/and the burst head that step 4.1 enters sends to step 4.0 through selected light path control channel; Again the burst packets of correspondence is also sent to step 4.0 through the data channel of this light path subsequently;

Whether step 3.0. packet arrives local node: the destination address that the data packet head that enters through the OCS light path according to step 1.2 writes down judges whether this packet arrives local node; If then change step 5.0; Otherwise return step 1.0;

Whether step 4.0. burst head/burst packets arrives local node: by the packet that step 2.2 enters through the OBS light path, judge according to the destination address of burst head record whether this packet arrives local node; If then change step 5.0; Otherwise change step 4.1;

Step 4.1. transmits processing: by the packet that step 4.0 enters, determine to transmit light path according to the destination address and the OBS routing table of its burst record, and be corresponding burst packets reservation data channel, successfully then return step 2.2 transmission if preengage; Carry out step 2.2,4.0,4.1 repeatedly, arrive local node 5.0 until packet; Otherwise change step 6.0;

Step 5.0. receives packet: or/and step 4.0 arrives the packet of local node, be transmitted to destination address after handling according to a conventional method by step 3.0;

Step 6.0. discard processing: will abandon by the reservation data channel that step 4.1 changes over to not successful burst head and burst packets, and the record amount of abandoning.

Ratio 〉=1 of the shared wavelength resource of OCS light path and the shared wavelength resource of OBS light path in the above-mentioned network.

Two kinds of exchanged forms of the OCS that the present invention will adopt usually, OBS organically combine the composition hybrid optical switching network, and are had the exchange capacity of OBS and OCS simultaneously by the network node that OBS module and OCS module are formed; When network normally moved, all data streams all transmitted by OCS light path layer; When the sudden growth of data volume causes OCS light path overload, send the flood traffic that it surpasses the carrying of OCS light path by the OBS light path again; And when network breaks down, when one or more OCS light path fault occurring, also by this OBS light path (layer), the data flow of being obstructed is continued to transmit; Promptly flood traffic that under the condition that any standby light path is not set, just factor a tree name amount burst growth can be produced and the data flow of being obstructed because of the light path fault are sent to destination node in time, safely.Thereby have utilization rate of network resource and efficiency of transmission height, improved fail safe and reliability that data (business) transmit effectively, characteristics such as packet loss descends significantly, and the operating cost of network is low.

Description of drawings

Fig. 1 is a hybrid optical switching network data transport stream journey schematic diagram of the present invention;

Fig. 2 is a mixed optical network overall architecture schematic diagram of the present invention;

Among the figure: A, B, C, D are the OBS Switching Module, and a, b, c, d are the OCS Switching Module, and A-a, B-b, C-c and D-d are respectively 4 nodes of network; Frame of broken lines represents that along the burst head and the burst packets of the transmission of OBS light path solid box is represented along the packet of OCS light path transmission;

Fig. 3 is that the data of embodiment 1 transmit schematic diagram;

Wherein, A, B, C, D, E represent the light burst-switched module in the network node, a, b, c, d, e are the OCS Switching Module, when m, n represent all that the OCS light path is unimpeded by the light path data carried by data, h, b are illustrated respectively in burst head and the burst packets that the OBS layer transmits, heavy line is represented an OCS light path from A to C, and dotted line is represented the OCS light path from A to D, and the OBS layer path of A to C represented in two-dot chain line.

Fig. 4 is an embodiment 2NSFNET-14 topology of networks schematic diagram; 0-13 represents 14 node locations of network respectively among the figure.

Embodiment:

Embodiment 1: present embodiment is an example with the network of being made up of five nodes, on every optical fiber 5 wavelength is arranged in the network, and each link is two-way link, and accompanying drawing 3 transmits principle schematic for this instance data:

A. set up hybrid optical switching network: according to traffic matrix $T=\left[\begin{array}{ccccc}0& 0& 0& 20& 50\\ 0& 0& 10& 0& 0\\ 3& 0& 0& 0& 0\\ 0& 0& 4& 0& 15\\ 0& 7& 0& 0& 0\end{array}\right]$ Set up OCS light path: a-b-c-d-e, a-b-c-d, d-e, b-d-c, e-c-a-b takies 12 wavelength altogether; The average bearing capacity (10 of each light path ⁷Bps) be respectively: 50,20,15,10,7; OBS layer and physical topology network isomorphism, OBS layer wavelength available are all the other 8 wavelength resources, wherein on every link with a wavelength channel as the control channel that transmits the burst head, other wavelength channels are as the data channel that transmits burst packets;

B. data transmit: promptly transmit according to the following steps after data flow enters nexus:

Step 1.0.OCS light path is selected: order address, source and OCS optical routing table according to each packet are determined light path and corresponding output port;

Step 1.1. judges whether light path is unimpeded: whether taking situation (present embodiment buffer memory higher limit is 100 IP block lengths) according to the real time information of the light path detection module in the network node and light path buffer memory, to judge the light path of port correspondence unimpeded, if the unimpeded step 1.2 of then changeing of light path is (promptly when light path is in the normal duty state, packet is transmitted by respective optical path, present embodiment arrives destination node according to the 1.0-1.1-1.2-3.0-5.0 step successively), otherwise (promptly when light path overload or light path are interrupted then) commentaries on classics step 2.0;

Step 1.2. data send: will put into the light path buffer memory by the data that step 1.1 enters, and the recording beam path buffer memory takies situation, then the packet of the team in the buffer memory is sent to step 3.0 through the OCS light path;

Step 2.0 burst packets/first-born one-tenth happens suddenly: will be converged according to minimum length-maximum binding time method (Min-Burst-Length Max-Assembly-Period algorithm) by 1.1 packets that enter through step 1.1.1 or 1.1.2 and be burst packets, generate corresponding burst head simultaneously, (length threshold is that 100 IP divide group leader in the convergence processing, and time threshold is 0.02 second) changeed step 2.1 then and determined OBS layer route;

Step 2.1 is determined OBS route (transmission light path): the forwarding port that local node that intend to arrive by burst packets and OBS routing table are determined next jumping and this node place is (when light path a-b-c-d-e transships, after the burst head is assembled and generated to its overload data as overflow data through burst packets, the OBS route of determining is: a-b, b-c, c-d, d-e), changeing step 2.2 then sends;

Step 2.2 sends burst head and burst packets: will be by step 2.1 or/and the burst head that step 4.1 enters at first sends to step 4.0 through the control channel that leads to next-hop node, continue after again the burst packets of correspondence is sent to step 4.0 (when being light path a-b-c-d-e overload, burst head and burst packets are promptly by the order forwarding of a-b-c-d-e, end up to e) through the data channel that leads to same node point;

Whether step 3.0 arrives local node by the packet that the OCS light path transmits: by the packet that step 1.2 is sent into, judge according to the destination address of noting down in the packet whether this packet arrives local node; If then directly change step 5.0; Otherwise return step 1.0;

Step 4.0 judges whether burst head/burst packets arrives local node: the packet by step 2.2 enters judges whether to arrive local node according to the destination address on its burst head (for example being e); If then change step 5.0; Otherwise change step 4.1; (during light path a-b-c-d-e overload, wherein the route of overflow data bag is: a-b, b-c, c-d, d-e; Arrive network node b this moment, and c, the packet of d need to transmit after this step is judged and handle, and could arrive destination address e);

Step 4.1OBS transmits processing: the packet that is entered by step 4.0, the forwarding port that local node (for example e) that the plan that writes down according to the burst head arrives and OBS routing table are determined next jumping and this node place, and be corresponding burst packets reservation wavelength resource according to information in the burst head, preengage and successfully then return step 2.2 if lead to the wavelength resource of next-hop node; (during light path a-b-c-d-e overload, the burst head need be at b, c, reservation wavelength resource in d place is preengage successfully and burst head and burst packets could be continued to forward) otherwise change step 6.0;

Step 5.0 arrives the data processing behind the local node: will be by step 3.0 or/and the destination address processing such as line data amount and average delay data statistics of going forward side by side are handled and be forwarded to the packet that step 4.0 enters;

Step 6.0 abandons burst head/burst packets, the record amount lost: will be made discard processing and be write down its amount lost simultaneously by the packet that the reservation that step 4.1 enters is failed.

Embodiment 2: present embodiment adopts the NSFNET-14 network, and the physical topology network configuration as shown in Figure 4.Link is a two-way link in the network, and the wavelength multiplexing number is 16, and traffic matrix is:

$T=\left[\begin{array}{ccccc}0& 581& 0& 342& ...\\ 777& 0& 1171& 856& ...\\ 4& 109& 0& 206& ...\\ 0& 0& 0& 0& ...\\ ...& ...& ...& ...& ...\end{array}\right]$

A. set up hybrid optical switching network: the OCS light path of setting up according to traffic matrix T is respectively: 0-1, and 1-0,1-2,1-0-4-3 ... totally 119, the average bearing capacity of each light path then is respectively 581,777,1171,856, OBS network configuration and physical topology network configuration isomorphism, OCS light path are set up the equal dispensing OBS of the remaining wavelength resource in back; When definite OBS layer route, present embodiment calculate earlier node to preceding K bar shortest path (K gets 4), carry out routing overhead optimization then, obtain the OBS routing table;

B. the transfer step of packet:

Several a tree name streams that present embodiment enters network are fixed length 1250BytesIP bag, the wavelength channel transmission rate is 10Gb/s, burst packets converges and adopts the minimum length-maximum binding time method identical with embodiment 1 (length threshold is 100 IP packet lengths, time threshold is 200 μ S), the unit shift time is 20 μ S.The transfer step of packet is identical with embodiment 1.

Present embodiment contrasts through the simulation run experiment: emulation platform is based on OPNET, test is to carry out under the condition of identical resource distribution and network traffic dynamic change, experiment content is with single optical circuit exchange (OCS) network OCS network of protection (promptly based on) and traditional parallel type hybrid optical switching network and the contrast of hybrid optical switching network of the present invention on packet loss: 1. during the network underload, and when the stale link way is respectively 1,2,3 o'clock, packet loss based on the OCS network of protecting is respectively 1.82%, 5.89%, 10.98%, the packet loss of parallel type hybrid optical switching network is respectively 2.95%, 7.55%, 10.42%, and the packet loss of network of the present invention only is 0%, 0%, 0.8%; 2. during the network intermediate part load, the number of links that lost efficacy also is respectively 1,2,3 o'clock its packet loss: the OCS network is followed successively by 1.61%, 6.28%, 15.1%, the parallel type hybrid optical switching network is followed successively by 4.65%, 8.73%, 12.74%, and the present invention is followed successively by 0,1.27%, 3.28%; 3. during the network heavy duty, the number of links that lost efficacy is respectively 1,2,3 o'clock packet loss: the OCS network is followed successively by 1.14%, 10.61%, 15.5%, the parallel type hybrid optical switching network is followed successively by 5.69%, 9.84%, 14.69, and side of the present invention is followed successively by 0,2.48% and 4.21%.Packet loss of the present invention is all well below optical circuit exchange (OCS) network and traditional parallel type hybrid optical switching network based on protection.

Claims (2)

1. the transmission method of a hybrid optical switching network comprises:

A. set up hybrid optical switching network:

At first, set up light path, form the OCS transport layer according to data volume, link wavelength available information, simultaneously for homology order node not to definite OCS route and set up corresponding routing table; And then the OBS transport layer is set, the wavelength available of every link of configuration OBS layer, for homology order node not to definite OBS route, and set up corresponding routing table; When each link wavelength available of configuration OBS layer, every link all uses a wavelength channel as control channel, is used for transmitting the burst head, and all the other wavelength channels are used to transmit burst packets; Each node still is made up of OBS module and OCS module in the network;

B. data transport stream journey comprises:

Step 1.0. selects the OCS light path: according to the order address, source and the OCS routing table that enter network packet, determine OCS transmission light path;

Step 1.1. judges whether light path is unimpeded: at the light path of being selected by step 1.0., take situation according to the real time information of light path detection module in the network node and light path buffer memory and judge whether light path is unimpeded, if not smooth, then change step 2.0 processing through 1.1.1 or 1.1.2; Otherwise change step 1.2;

Step 1.2. packet sends: will put into the light path buffer memory by the data that step 1.1 enters, and the recording beam path buffer memory takies situation, then the packet of the team in the buffer memory is sent to step 3.0 through the OCS light path;

Step 2.0. burst packets/first-born one-tenth happens suddenly: when by step 1.1 through 1.1.1 or 1.1.2 enter overflow data in buffer reach converge threshold value after, it converged be burst packets, generate corresponding burst head simultaneously, change step 2.1 then;

Step 2.1. determines that OBS transmits light path: after determining that according to happen suddenly a destination node information of record and OBS routing table OBS transmits light path, change step 2.2 transmission;

Step 2.2. sends burst head and burst packets: at first will be by step 2.1 or/and the burst head that step 4.1 enters sends to step 4.0 through selected light path control channel; Again the burst packets of correspondence is also sent to step 4.0 through the data channel of this light path subsequently;

Whether step 3.0. packet arrives local node: the destination address that the data packet head that enters through the OCS light path according to step 1.2 writes down judges whether this packet arrives local node; If then change step 5.0; Otherwise return step 1.0;

Whether step 4.0. burst head/burst packets arrives local node: by the packet that step 2.2 enters through the OBS light path, judge according to the destination address of burst head record whether this packet arrives local node; If then change step 5.0; Otherwise change step 4.1;

Step 4.1. transmits processing: by the packet that step 4.0 enters, determine to transmit light path according to the destination address and the OBS routing table of its burst record, and be corresponding burst packets reservation data channel, successfully then return step 2.2 transmission if preengage; Carry out step 2.2,4.0,4.1 repeatedly, arrive local node 5.0 until packet; Otherwise change step 6.0;

Step 5.0. receives packet: or/and step 4.0 arrives the packet of local node, be transmitted to destination address after handling according to a conventional method by step 3.0;

Step 6.0. discard processing: will abandon by the reservation data channel that step 4.1 changes over to not successful burst head and burst packets, and the record amount of abandoning.

2. by the transmission method of the described a kind of hybrid optical switching network of claim 1, it is characterized in that ratio 〉=1 of the shared wavelength resource of OCS light path and the shared wavelength resource of OBS light path in the network.

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