CN102186125B - Special Subtree-based multilayer multicast protection method in WDM (Wavelength Division Multiplexing) network - Google Patents

Abstract

The invention provides a special subtree-based multilayer multicast protection method in a WDM (Wavelength Division Multiplexing) network, and belongs to the technical field of network communication. The method comprises the following steps of: establishing a working multicast forest; establishing a protective multicast forest; protecting a WDM layer; and removing a business. In the invention, a special subtree-based multicast protection method is established under the condition that the failure of a single link is taken into consideration, the number of damaged businesses is reduced through two means when a physical link is in failure, and damaged sub-trees and influenced businesses are reduced in case of failures; thus, the application range of the traditional special multilayer multicast protection method can be extended, and a plurality of constraint conditions are taken into consideration during multilayer protection.

Description

The dedicated multi-layered guard method of the multicast based on subtree in a kind of WDM optical-fiber network

Technical field

The invention belongs to networking technology area, be specifically related to the dedicated multi-layered guard method of the multicast based on subtree in a kind of WDM optical-fiber network.

Background technology

Along with the high speed development of the Internet, capacity and the performance of people to communication system proposed new requirement.Wavelength division multiplexing (Wavelength Division Multiplexing, WDM) technology can provide huge transmission capacity, meets the demand of Internet service to bandwidth.But, once there is network failure, will cause a large number of services to interrupt.Meanwhile, in order to reduce network operation cost, improve bandwidth resources utilance, transmission network is developed to IP over WDM double-layer structure by traditional IP over ATM over SDH/SONET over WDM multiple-layer overlapped structure gradually, and IP operation is directly carried on WDM optical-fiber network.

The dedicated multi-layered guard method of multicast in traditional optical-fiber network; mostly only consider the dedicated multi-layered guard method of link failure under single restraint condition; its scope of application is narrower; do not consider the multiple constraint situation such as the constraint of optical transceiver number, sparse wavelength conversion constraint, do not consider the recovery amount of action reducing when breaking down and the resource utilization that improves light path yet.

Summary of the invention

The problem existing for above-mentioned prior art; the invention provides the dedicated multi-layered guard method of the multicast based on subtree in a kind of WDM optical-fiber network; considering under the prerequisite of single link failure; build multicast privacy protection method based on subtree; reduce the quantity of the impaired business in the time that physical link breaks down by two kinds of modes, reduced subtree and affected business impaired under failure condition.

The dedicated multi-layered guard method of the multicast based on subtree in WDM optical-fiber network of the present invention, comprises the steps:

Step (1), set up work multicast forest

Adopt multicast service amount congestion relief algorithm for asking to set up work multicast forest; If Traffic grooming failure, algorithm finishes so.

Step (2), foundation protection multicast forest

It is that physical link separates that protection multicast forest requires with work multicast forest;

The physical link of step (2.1), light path separates

Wavelength span on each physical link of light path process is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

The physical link of step (2.2), subtree separates

Step (2.2.1), search the destination node of dredging by this subtree;

Step (2.2.2), start to recall light tree along the opposite direction of business data flow from destination node, the wavelength span of these destination node business data flow processes dredged in record;

Step (2.2.3), obtain its corresponding physical link according to these wavelength spans, wavelength span on these physical links is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

After being provided with and separating with the physical link of the tree of working with said method, utilize multicast service amount congestion relief algorithm to set up protection multicast forest for request, if protection multicast forest creates unsuccessfully, discharge so the resource taking in work multicast forest, algorithm is failed, end.

Step (3), protection WDM layer

The protection of WDM layer is divided into two classes: the protection of the protection of counterweight operating load light path and counterweight operating load subtree;

The protection of step (3.1), counterweight operating load light path

When having set up for service request after working LSP and protection LSP, check successively working LSP each logical links of process, all corresponding light paths of every logical links, if its load has exceeded the threshold value of specifying

and the protection of WDM layer is not provided, and for this light path creates a protection light path, protection light path need to separate with its physical link so; The source node that makes this heavy operating load light path is v _a, destination node is v _b, concrete steps are as follows:

Step (3.1.1), link cost is set

The link cost of the corresponding all wavelengths link of physical link of heavy operating load light path process is set to ∞; The link cost of all logical links is set to ∞;

According to formula

the link cost W of all the other wavelength spans is set _wll;

Wherein: w _w, w _poperating wave long number and protection number of wavelengths in the affiliated physical link of this wavelength span respectively;

According to formula

v ' is set _aall go out edge joint receive the link cost W of link _al;

According to formula

v ' is set _ball enter edge joint receive the link cost W of link _al;

Wherein: t _t, r _t, t _a, r _arepresent respectively the total optical transmitter number of this Nodes, total optical receiver number, available light transmitter number and available light receiver number;

All the other receive the link cost of link to be set to ∞;

Step (3.1.2), pathfinding

Step (3.1.2.1), with dijkstra's algorithm calculate one connect v ' _aand v ' _bthe path of Least-cost, judge whether pathfinding success;

Step (3.1.2.2) is if failed, and WDM layer is protected unsuccessfully, and algorithm finishes;

Step (3.1.2.3), if this heavy operating load light path is labeled as " WDM layer is protected " state by success, continues lower step 3);

Step (3.1.3), Resources allocation

Protection light path source node place available light transmitter number subtracts one; Light path destination node place available light receiver number subtracts one; Each wavelength span use state of protection road process is set to " being used to protection ";

The protection of step (3.2), counterweight operating load subtree

The protection of counterweight operating load subtree refers to that the load of working as subtree is higher than the threshold value of specifying

time, adopt multicast protection algorithm for it provides the protection of WDM layer, if protected successfully, this subtree or light path are labeled as to " protection of WDM layer " state, otherwise, do not process.

Step (4), business are left away

Step (4.1), discharge the bandwidth taking in work multicast forest and protection multicast forest each light path successively;

Step (4.2), for WDM layer protection is provided but its operating load lower than threshold value

light path, delete its protection road, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of protection road process is set is " not using ";

Step (4.3), for the light path that dedicated bandwidth is 0, delete this light path: the service condition that each wavelength span of light path process is set is " do not use "; Light path source node place optical transmitter number adds one; Destination node place optical receiver number adds one;

Step (4.4), discharge the bandwidth taking on the each light tree of work multicast forest and protection multicast forest successively;

Step (4.5), discharged after bandwidth, for the protection of WDM layer is provided but its operating load lower than threshold value

light tree, delete all protections sections of this light tree, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of each protection section process is set is " not use ";

Step (4.6), for dedicated bandwidth is 0 light tree, delete this light tree: the service condition that each wavelength span of light tree process is set is " not using "; Light path source node place optical transmitter number adds one; All destination nodes place optical receiver number adds one.

The dedicated multi-layered guard method of the multicast based on subtree in WDM optical-fiber network of the present invention, can expand the range of application of the dedicated multi-layered guard method of traditional multicast, considers multiple restraint conditions in carrying out multilayer protection.

Accompanying drawing explanation

Fig. 1 be network configuration by multiple-layer overlapped the schematic diagram to two-layer evolution;

Fig. 2 is the schematic diagram of overlay model;

Fig. 3 is the schematic diagram of peer-to-peer model;

Fig. 4 is the physical topology schematic diagram of (physical topology N) for example;

Fig. 5 is the schematic diagram of the wavelength hierarchical diagram that physical topology N is corresponding (wavelength hierarchical diagram G);

Fig. 6 is the schematic diagram of network model;

Fig. 7 is the schematic diagram of network node;

Fig. 8 is wavelength hierarchical diagram;

Fig. 9 is basic multilayer auxiliary view;

Figure 10 has added to receive the multilayer auxiliary view after link;

Figure 11 is the schematic diagram that the physical link of subtree separates.

Embodiment

Below in conjunction with accompanying drawing, the dedicated multi-layered guard method of the multicast based on subtree in WDM optical-fiber network of the present invention is described in further detail.

One, optical-fiber network basic platform

1 IP over WDM network overview and key technology thereof

1.1WDM technology

Growing continuously and fast of mobile service, 3G emerging service is saved up strength to start out, and the Internet services such as long-distance education, video conference, video request program, ecommerce flourish makes data traffic be explosive increase.Capacity, function and the performance of the business demand of explosive increase to communication system proposed new requirement.

The straightforward procedure that increases communication system bandwidth is to lay more optical fiber, costs dearly, and be subject to the restriction of the physical conditions such as natural environment, poor expandability but lay optical fiber.Another method is to adopt time division multiplexing (Time Division Multiplexing, TDM) technology, and it has improved transmission bit rate, but that the transmission capacity of simple optical fiber is still is limited, can not effectively utilize fiber bandwidth.Under this background, wavelength division multiplexing (Wavelength Division Multiplexing, WDM) technology is arisen at the historic moment.Wavelength division multiplexing is a kind of technology of transmitting multiple different wave length optical carriers in same optical fiber.The optical carrier of different wave length is merged together by multiplexer (Multiplexer) at transmitting terminal, be put in an optical fiber and transmit; The optical carrier of different wave length is separated by demodulation multiplexer at receiving terminal, be converted to original signal via optical receiver.In optical fiber, each wavelength independently transmits, and is independent of each other, and has improved greatly the transmission capacity of optical fiber, makes wavelength division multiplexing become best network capacity extension mode.Along with the reduction of optical device cost, and breakthrough and the maturation of the new technologies such as modulation technique, electronic dispersion compensation, super out-of-band FEC coding such as DQPSK, DP-QPSK, single wavelength 40Gbit/s, the systems such as transmission-link capacity 1.6Tbit/s are commercial.It is that 10.9Tbit/s (273 × 40Gbit/s) and total amount are the up-to-date world record of transmission capacity of 10.2Tbit/s (256 × 40Gbit/s) that Japan NEC and French Alcatel have been realized respectively total amount in 100km distance.

Traditional point-to-point wdm system structure adopts simple linear mode, with the dilatation of wavelength path mode, a large amount of original bandwidth can be provided, it need to introduce jumbo flexible optical node device at network node place just can be converted into the bandwidth that actual networking can flexible Application, realize WDM layer interconnected, construct optical transfer network (Optical Transport Network, OTN).This class optical node device mainly comprises reconfigurable light bifurcated multiplexer (Optical Add-Drop Multiplexer, OADM) and optical cross connect (Optical Cross Connect, OXC).By introduce OADM at nodes place, can insert in this locality the wavelength of Huo Xia road one group selection, flexibly upper and lower traffic carrying capacity.Along with WDM network is towards the future development of mesh network, need to realize more coarsegrain at network hub node place, comprise wavelength, wavestrip, so that processing light signal in optical fiber granularity, introduce OXC at hub node place and necessitate.It mainly completes in functions such as connection, bifurcated, protection and the recoveries of wavelength, wavestrip and optical fiber rank.

Press application type, OXC can be divided into optical fiber interconnection (Fiber Cross Connect, FXC), wavelength is selected interconnection (Wavelength Selective Cross Connect, and wavelength exchange interconnection (Wavelength Interchange Cross Connect, WIXC) WSXC).FXC exchanges on any output optical fibre disposable all wavelengths on an input optical fibre; WSXC exchanges to a wavelength on an input optical fibre on the Same Wavelength on any output optical fibre; WIXC has wavelength conversion capability, a wavelength on an input optical fibre can be exchanged on any one wavelength on any output optical fibre.By implementation, OXC can be divided into the OXC (OEO-OXC, electric OXC) that adopts electric cross matrix and the OXC that adopts full optical cross-matrix (OOO-OXC, full light OXC).Electricity OXC is converted to the signal of telecommunication by opto-electronic conversion by light signal, carries out after interconnection processing, then is converted to light signal output.Full light OXC does not need to carry out opto-electronic conversion, and all intersections are all carried out at WDM layer.OADM and OXC only select the upper and lower road of the wavelength of local service, and other wavelength are expedite by network node, are referred to as bypass.OADM and OXC have reconfigurability flexibly, make network have wavelength routing capabilities, set up wavelength path (light path, lightpath) end to end.Along with the continuous progress of OADM and OXC technology, WDM optical-fiber network develops towards complete mesh network from linear, ring network gradually.

Although OXC has networking capability flexibly, traditional OXC only has static configuration ability.In recent years, IP operation becomes the main business amount of network service gradually, due to uncertainty and the Unpredictability of IP operation, require more and more urgent to the dynamic-configuration of the network bandwidth, network need to have the ability of dynamic-configuration, and traditional mode time and effort consuming by human configuration is easily made mistakes, and can not configure in time, its shortcoming manifests gradually.WDM optical-fiber network will adapt to the demand of new business; huge bandwidth capacity must can be made full use of; reasonably distribution service; as soon as possible for business connects; and provide protection and Restoration Mechanism; the service of different service quality (Quality of Service, QoS) grade can also be provided according to the demand of business simultaneously.ASON (Automatic Switched Optical Network, ASON) ^[5,6]under such background, produce.It is the connection of managing network automatically, and this optical-fiber network with independent control plane is called ASON.

ASON can be found the variation of topology, resource and business automatically; Can be fast with set up dynamically light and be connected, realize the dynamic assignment of Internet resources; Introduce the mechanism of protection and restoration of basic mesh network, can adopt mode more flexibly protect and recover for business provides; How novel high speed can be provided and increase income business, for example, super band width service and nonstandard bandwidth business, bandwidth on-demand business, the configuration of dynamic virtual ring and end to end circuit configuration service, virtual optical network business etc.At present, the positive formulation work of carrying out ASON domain-specific standard of the International Standards Organization such as International Telecommunications Union (ITU-T), internet engineering task group (IETF), OIF Optical Internetworking Forum (OIF) and Guang Yu services interconnection alliance (ODSI).

1.2 network model

Along with business developments such as video conferences, the diversification gradually of Internet business, IP operation becomes main data traffic.WDM optical-fiber network, as leading transport network, provides huge transmission capacity.The fusion of IP and WDM becomes the trend of future network development.The interconnect model of transmission network is also developed to IP over WDM double-layer structure by traditional IP over ATM over SDH/SONET over WDM multiple-layer overlapped structure gradually, as shown in Figure 1.In the network configuration of multiple-layer overlapped; IP layer is used to provide business; ATM layer provides service quality (Quality of Service for service connection; QoS) guarantee; SDH/SONET layer utilizes its guard ring mechanism to protect and Restoration Mechanism for network provides, and WDM layer provides huge transmission bandwidth.But in multiple-layer overlapped network configuration, the cell mechanism of ATM has been brought larger overhead, has reduced bandwidth for transmission efficiency.Along with WDM optical-fiber network is developed to mesh network by looped network, although SDH/SONET protection mechanism is effective fast, its protection cost is higher, and the protection mechanism of SDH/SONET is no longer applicable.In order to reduce network operation cost, improve bandwidth resources utilance, ATM layer and SDH/SONET layer fade away, and transmission network finally develops into the two-tier network structure of IP over WDM, and IP operation is directly transmitted on WDM optical-fiber network.

In IP over WDM network, there are three kinds to control model, be respectively overlay model, peer-to-peer model and extended model.

(1) overlay model

Overlay model claims again client/server model, is proposed by ITU-T.As shown in Figure 2, in this model, IP layer and WDM layer are separate, have control plane separately, move different Routing Protocols, the routing iinformation such as switching network topology not between Routing Protocol.IP layer and WDM layer are by user-network interface (User to Network Interface, UNI) link together, WDM layer is made up of subnet, interconnected by Network-Network interface (Network to Network Interface, NNI) between each subnet.This model can be realized effective subnet and divide, and facilitates control and the upgrading etc. of each subnet.IP layer can only be seen the light path of setting up between edge device in WDM layer, and in this model, the internal structure of WDM layer network is transparent to IP layer.IP layer to WDM layer proposition business transmission request, is responsible for the control of light path by UNI by WDM layer, the intelligence of network is reflected in WDM layer completely.This model has been realized to greatest extent WDM layer and has been separated with the control of IP layer.The shortcoming of overlay model is the light path of setting up between WDM layer edge device, be reflected as the logical links of IP layer, and the LSA of these links can cause very large network overhead.

(2) peer-to-peer model

Peer-to-peer model is proposed by IETF.As shown in Figure 3, in this model, IP layer and WDM layer are reciprocity, return unified control plane management.IETF is by this control plane called after GMPLS (GeneralizedMulti-protocol Label Switching, GMPLS).In peer-to-peer model, ip router and OXC are all called as LSR (Label Switching Router, LSR), they move identical route and signaling protocol, the routing iinformation such as exchanging chain line state to each other, IP layer can be seen the internal structure of WDM layer, and WDM layer is no longer transparent to IP layer.In peer-to-peer model, because IP layer and WDM layer are reciprocity, between each LSR, need to exchange a large amount of Link States and signaling control information, cause very large network overhead.The internal structure of WDM network, no longer to user transparent, is unfavorable for the stable of network, is also unfavorable for the division of subnet in WDM network; IP layer and WDM layer recovery mechanism, need unified coordination, controls complicated.

(3) extended model

In extended model, IP layer and WDM layer are separate, move independently Routing Protocol, but can exchange some reachability information by UNI between them.Be for example the OXC distributing IP address in WDM network, then offer IP layer by WDM layer Routing Protocol and use, realize automatic pathfinding etc.The key issue of this model is how to exchange reachability information at UNI place.

The present invention is mainly for peer-to-peer model.

1.3 IP over WDM network key technology

In IP over WDM network, IP layer provides layer as business, and WDM layer is as transport layer, and its key issue is how to realize the seamless link of IP layer and WDM layer, and the GMPLS that IETF proposes provides a good solution thinking.In addition; the low speed service bandwidth granularity that IP receives is generally less than single wavelength capacities; so how effectively by service convergence, then carry these low speed business with WDM layer in IP over WDM, and be problem demanding prompt solution for business provides corresponding protection/Restoration Mechanism.In order to address the above problem, mainly proposed at present GMPLS, Traffic grooming, with the key technology such as the closely-related route of Traffic grooming and Wavelength Assignment and network survivability.

1.3.1GMPLS technology

GMPLS is multi protocol label exchange (MPLS) product to the development of WDM layer, and it has realized the seamless fusion of IP layer and WDM optical-fiber network effectively.GMPLS has inherited nearly all excellent characteristic such as traffic engineering in MPLS, mpls protocol is expanded simultaneously.GMPLS is absorbed in control plane, supports the exchange of the multiple resources granularities such as packet switching, time-division switching, wavelength exchange and space switching (optical fiber exchange).GMPLS also supplements and revises original signaling and routing protocols in MPLS, and has designed brand-new LMP Link Manager Protocol (Link Management protocol, LMP).

(1) general multiple protocols label

GMPLS has defined five kinds of interface types, respectively: (a) packet switch capable (Packet Switch Capable, PSC): carry out packet switching, by identification boundaries of packets, forward grouping according to the information of packet header.(b) second layer Fabric Interface (Layer2 Switch Capable, L2SC): carry out cell switching, the border of passing through by identification, forwards cell according to the information of cell head.(c) time division multiplexing capable (Time Division Multiplexing Capable, TDMC): carry out business forwarding according to TDM time slot.(d) lambda switch capable (Lambda Switch Capable, LSC): according to the optical wavelength of bearer service or optical band forwarding service.(e) fiber switch capable (Fiber Switch Capable, FSC): the physical location according to optical fiber in physical space forwards.GMPLS has done expansion to the label in MPLS, makes it also can carry out mark to TDM time slot, wavelength, wavestrip, optical fiber etc.GMPLS unifies mark to IP exchanges data, TDM circuit switching and the exchange of WDM light.Packet switching label continues to adopt the label in MPLS, and circuit switching and light switch label have been re-started to definition, comprises request label, universal tag, suggestion label, sets label etc.Wherein, request label is for the foundation of label switched path (LabelSwitching Path, LSP); Universal tag is used for setting up after LSP, and indication is along the service conditions of LSP transmission; When suggestion label is used for configuring LSP, the time delay of avoiding reverse configuration to cause, Rapid Establishment light connects; Set label and select the scope of label for limiting downstream node.

(2) common tags switching path

Due to the exchange of GMPLS support different resource granularity, in the time setting up LSP for fear of the waste of bandwidth resources, the LSP of inferior grade (PSC, L2SC, TDMC, LSC, FSC grade reduce successively) need to be nested in high-grade LSP, be called again LSP classification.LSP classification technique is realized by GMPLS labeled slots, after allowing entrance identical inferior grade LSP to converge, transparent in high-grade LSP, then distal portion from.Use the device interface types of every LSP starting and ending of LSP sizing specification identical.Same-interface refers to that the interface of certain grade can use the multiplexing multiple LSP of certain technology.In MPLS, set up bidirectional LSP and must set up the unidirectional LSP of two opposite directions, its setup delay is long, signaling consumption is large.GMPLS improves it, can set up bidirectional LSP.While setting up bidirectional LSP, require the LSP of both direction to there is identical traffic engineering parameter, comprise resource requirement, protection/Restoration Mechanism etc.When GMPLS sets up bidirectional LSP, the path of uplink and downlink adopts same signaling message, and two LSP set up simultaneously, effectively reduces the time delay that LSP sets up, and has reduced signaling consumption.

(3) link management

In optical-fiber network, between two adjacent OXC, in the quantity of parallel optical fiber link and every optical fiber, multiplexing number of wavelengths is huge, provide broadcast mechanism if be respectively it, can cause link maintenance and broadcast time, the amount of information of transmission is very large, is unpractical for every optical fiber, each wavelength provide an IP address simultaneously.For this reason, GMPLS has adopted link bundling and has processed this problem without the mode of numbering link.If parallel link belongs to identical link group, these links can be bound so, form a bar bundle link.Identical link group refers to shared risk link group (Shared Risk Link Group, the SRLG) numbering that belongs to identical, identical link type of coding, identical protection/recovery type.Greatly reduce like this size of LSD, reduced the signaling consumption that broadcast brings.Refer to without numbering link, adopt the mode of (router id, link number) two tuples to identify the address of link, replace with this mode that uses IP address designation.GMPLS has formulated LMP Link Manager Protocol, is responsible for the functions such as control channel management between two adjacent nodes, link summary, link verification, fault management, and wherein link verification and fault management are optional.

(4) route and signaling protocol

When GMPLS adopts general multiple protocols label to set up LSP; need to consider the factor of bandwidth and protection/recovery capability; this requires node need to record link-state information; defined MPLS traffic engineering two signaling protocol RSVP and LDP are expanded to respectively RSVP-TE and CR-LDP by GMPLS for this reason, exchanges the parameters such as the bandwidth, type, protection/Restoration Mechanism of LSP by signaling.Route Selection both can adopt explicit routing method, also can adopt the method for multi-hop.In addition, GMPLS also expands to respectively OSPF-TE and IS-IS-TE by the Routing Protocol OSPF for traffic engineering control in territory and IS-IS.The link management mechanism such as the binding of GMPLS link, LMP Link Manager Protocol have well reduced the expense that in route and signaling protocol, maintenance link state information is brought.

1.3.2 route and Wavelength Assignment

Given one group of connection, creates a light path and distributes the process of a wavelength to be called route and Wavelength Assignment (Route and Wavelength Assignment, RWA) for each connects.Connection request can be divided into two kinds: static connection request and dynamically connection request.For static traffic, the set of service connection request is given in advance, its target is to set up light path for these connection requests, and in global scope, minimize Internet resources used, such as number of wavelengths, fiber count etc., be the number of wavelengths of given fixed number, for connection request as much as possible is set up light path.Static routing and assignment of wavelength are called as static light path and set up (Static Lightpath Establishment, SLE) problem.For dynamic service, in the time that connection request arrives, for it sets up light path, after business is left away, cancel light path.Its target is that the business for dynamically arriving is set up light path, and reduces blocking rate as much as possible, or maximizes the quantity of setting up light path in synchronization network.Dynamic routing and Wavelength Assignment are called as dynamic light path and set up (Dynamic Lightpath Establishment, DLE) problem.

At present route and assignment of wavelength are decomposed into Route Selection and two subproblems of Wavelength Assignment.First find a best route (for example shortest path), then check and whether have available wavelength for distributing.If because the successional constraint of wavelength does not have wavelength can distribute to this route, calculate so again the route of suboptimum, continue to repeat said process, until find a route that meets wavelength continuity constraint, otherwise block connection request.Before finding this route, method possibly iteration many times, for this problem, has proposed the concept of wavelength hierarchical diagram, route and Wavelength Assignment is converted to the problem of graph theory, solves the problem of Route Selection and Wavelength Assignment simultaneously.

Define grid topology is N (R, A, L, W), and wherein R is the set of lambda router node, and A is the set of access node, and L is nonoriented edge, and W is the wavelength available number in every physical link.Each access node is bundled on a lambda router and provides electro-optical conversion to support electricity exchange.Each limit is made up of two reverse one-way optical fibers, on each optical fiber, can carry | W| wavelength channel.Definition wavelength layered graph model is G (V, E), and it is a directed graph.The process that obtains wavelength hierarchical diagram according to physical topology N is as follows: in N, each node i ∈ R copies in G | and W| time, these nodes are designated respectively if link l ∈ L connection route device i and router j, wherein i, j ∈ R, so for any w ∈ W,

by a directed edge

link together, wherein,

suppose that access node a ∈ A is connected on lambda router node r ∈ R.In G, for each access node a creates two nodes, one represents business generating portion (source), and another one represents business teste (object).These two nodes are designated respectively

in G, add

to node

and

arrive

directed edge.Therefore the number of node in G | V|=|R| × | W|+2 × | A|; The number of directed edge | E|=2 × | L| × | W|.For example, the wavelength hierarchical diagram that physical topology shown in Fig. 4 is corresponding as shown in Figure 5.Wherein, the link between every lambda router is made up of two reverse one-way optical fibers, and every optical fiber medium wave long number is 2.By wavelength hierarchical diagram, route just becomes relative simple with assignment of wavelength.As long as found the route that connects source and destination in certain wavelength plane, this route meets wavelength continuity constraint surely with regard to one.

1.3.3 Traffic grooming

WDM optical-fiber network provides huge transmission capacity, and the system of single wavelength capacities 40Gbit/s is commercial.But in actual applications,, the bandwidth on demand of each business is compared relatively low with single wavelength capacities, for example OC-12, OC-48, OC-192.Think that each low speed service request distributes a wavelength can cause a large amount of bandwidth waste.For each request creates a light path, also can increase the electric switching cost (for example needing to dispose more optical transceiver) of network, increase the cost of network.The most important thing is, the wavelength available number in real network is than few many of low speed business number that arrive.So Traffic grooming is the basic function that WDM optical-fiber network must have, to increase network throughput, improve wavelength resource utilance, reduce network cost.In WDM optical-fiber network, Traffic grooming is exactly the technology of transmitting in low speed service convergence to high speed light path, and its target is to minimize network cost or maximization network throughput.

In WDM optical-fiber network, Traffic grooming need to solve the problem of three aspects:: (1) sets up light path, and (2) distribute wavelength to meet wavelength continuity for light path, and (3) are route low speed business in logical topology.Whether given in advance according to business, Traffic grooming can be divided into two classes: static traffic amount is dredged with dynamic service amount and dredged.Dredge for static traffic amount, the method that these three problems can adopt shaping linear programming (Integer Linear Programming, ILP) to optimize solves together.But for catenet, the complexity of problem solving rises, and generally adopts heuritic approach to solve respectively three problems.In dynamic service amount is dredged, in the time that service connection request arrives, in logical topology, be first that it finds route, if object is unreachable or existing light path on bandwidth be finished, create so new light path carrying new business and connect.

1.3.4 network survivability

After network survivability refers to and breaks down, network can provide the ability of persistent service.Along with the development of WDM technology, can multiplexing hundreds and thousands of wavelength in single fiber, the capacity of each wavelength also reaches tens hundreds of Gbit/s even, once there is network failure (as link failure etc.), the service failure that can cause the Tbit/s order of magnitude, causes and has a strong impact on.Therefore the survivability of WDM optical-fiber network becomes the major issue of people's growing interest.

WDM layer Survivability technology can be divided into two classes: protection (Protection) and recovery (Restoration).It is the reserved reserved resource of business in advance that protection refers to when business connects, once break down, business turns by reserved resource carries.Protection has a shorter protection switching time, but due to needs reserved reserved resource in advance, and while not breaking down, reserved resource is idle, so resource utilization is low.Recovery refers to not in advance as the reserved reserved resource of business, and in the time that fault occurs, then according to network resource usage situation at that time, the mode of employing heavy-route, finds dynamically idling-resource and carry affected business.Recovery has higher resource utilization, but owing to being to find dynamically again available resources bearer service after fault occurs, so protection is long switching time, and heavier when offered load, while thering is no enough available resources, can cause fault recovery failure.

Whether share according to reserved resource, protection mechanism is divided into again two classes: privacy protection (Dedicated Protection) and share protect (Shared Protection).In privacy protection, to monopolize for certain the work reserved reserved resource in road, other protection road can not re-use.In share protect, if two work Lu Buhui break down (if two work roads are that physical link separates) simultaneously, they can share protect resource so.From the angle of resource utilization, share protect is higher than privacy protection resource utilization, and the traffic intensity of network is higher, and the advantage of share protect is more obvious.Protection switching time aspect, privacy protection is shorter than share protect.This is because in privacy protection, reserved resource is monopolized, can be pre-configured, once break down, just influenced business is switched in reserved resource; And in share protect, can not prejudge which service failure, and can not configure in advance, only have after fault occurs, then by devices such as the OXC on certain signaling mechanism configuration protection road, therefore its protection is longer switching time.

According to the granularity of protection, protection mechanism can be divided into again path protection, link protection and sectionalised protection.Path protection refer to for work road provide one to protect end to end road.Link protection refers to that once break down, the switching of business is responsible at faulty link two ends, participates in without sourcesink node into protection road of each link calculation on work road.In sectionalised protection, the road segmentation of first working, then be that each section is calculated a protection road, first section of tail of section is responsible for fault recovery.Comparatively speaking, path protection has higher resource utilization, and the fault recovery of link protection participates in without sourcesink node, has that to protect faster switching time, sectionalised protection be to attempt at the two seeking balance.

As the one in Survivability technology, resist technology has protects switching time faster, can meet the requirement of a large amount of real time business, so the present invention relates generally to resist technology.

2 network models

Network model can be described as oriented connected graph G _p(V, L, W), as shown in Figure 6.Wherein V, L, W represents respectively the wavelength set of node set, physical link set and every physical link of network, | V|, | L|, | W| represents respectively nodes, physical link number and every physical link medium wave long number of network.

2.1 network node

Network node is made up of the OXC combining and ip router.Wherein, ip router is responsible for admission service request.OXC forms (as shown in Figure 7) by wavelength switching matrix, low speed traffic grooming matrix and one group of tunable transceiver.Wavelength in input optical fibre, after demultiplexing, can directly exchange to the corresponding wavelength of output optical fibre by wavelength switching matrix and get on, or exchanges to optical receiving set and be transformed into the signal of telecommunication and enter low speed and dredge matrix.Belong to local business and transfer to ip router processing by low-speed service data flow port, non-local business is converted to light signal by optical transmitter, reenters wavelength switching matrix, and the respective wavelength that exchanges to corresponding optical fiber gets on.That is to say, in certain wavelength channel in input optical fibre, do not contain local service and can directly pass through wavelength switching matrix to output optical fibre, bypass; There is the wavelength channel of business up/down by processing under optical transceiver in electric territory.Each network node has been safeguarded overall link-state information, comprises the service condition of wavelength on each physical link, service condition of bandwidth etc. in each light path.

In addition, the constraints that the present invention considers mainly contains: wavelength continuity constraint, sparse part light splitting constraint etc. under the constraint of optical transceiver number, the conversion of sparse part wavelength.

(1) optical transceiver number

Each network node has been disposed optical transmitter and the optical receiver of some, and the present invention supposes that the optical transmitter of same node is identical with optical receiver number.

(2) wavelength conversion capability

Whether there is wavelength conversion capability according to node, node can be divided three classes: without wavelength conversion capability node, complete wavelength conversion capability node, part wavelength conversion capability node.

Refer to without wavelength conversion capability, the wavelength channel in input optical fibre can only exchange to the wavelength channel of identical wavelength in output optical fibre by wavelength switching matrix and get on.

Wavelength conversion capability refers to completely, and the wavelength channel that the wavelength channel in input optical fibre can exchange to any wavelength in output optical fibre by wavelength switching matrix gets on.

Part wavelength conversion capability, the wavelength channel that the wavelength channel in input optical fibre can exchange to wavelength in certain limit adjacent with this wavelength in output optical fibre by wavelength switching matrix gets on.For example, certain node has part wavelength conversion capability, and its wavelength conversion range is 2, wavelength X so ₄can transform to wavelength X ₂, λ ₃, λ ₅and λ ₆get on.The wavelength conversion range with the node of part wavelength conversion capability may be not identical yet.

In the present invention, for convenience, the wavelength conversion capability of the unified conceptual description node with wavelength conversion range, is that wavelength conversion range is 0 by the node label without wavelength conversion capability, and the node wave length conversion range with complete wavelength conversion capability is | W|.

(3) light splitting ability

In WDM optical-fiber network, if will make node there is multicast capability, need to be at node deployment optical splitter.According to the power of light splitting ability, network node can be divided three classes: without light splitting ability MI (Multicast Incapable), complete light splitting ability, part light splitting ability.

Refer to without light splitting ability, node can only be sent an input signal into an output port, if it is not multicast destination node, can only serve as so the non-bifurcation node in centre of multicast tree; If it is multicast destination node, it can only serve as the leaf node of multicast tree so.

Light splitting ability refers to completely, and node can be sent into input signal any number of output ports.

Part light splitting ability refers to, node can be sent into input signal the output port of some.

Latter two node is referred to as MC (Multicast Capable) node, both can be used as the destination node of multicast tree, also can be used as the intermediate node of light tree.When as middle node of divergence, for the node of complete light splitting ability, its out-degree does not limit; For the node of part light splitting ability, if it is not destination node, so its out-degree can not exceed its maximum can light splitting number; If simultaneously as destination node, need to separate a road light signal on this underground road, its out-degree can not exceed its maximum can subtract one by light splitting number.

Co-wavelength transfer capability is the same, for convenience, the present invention is unified can be made as 1 by light splitting number by maximum light splitting ability of can light splitting counting description node by the maximum of the node without light splitting ability, and has the degree that the node wave length conversion range of complete light splitting is node.

Existing wavelength conversion capability, has again the node of light splitting ability to have two kinds of node structures: (1) first carries out wavelength conversion, after carry out light splitting, (2) first carry out light splitting, after carry out wavelength conversion.The first node structure is simpler, and its two wavelength that separate must have identical wavelength, have certain limitation.The second node structure is more flexible, is the direction of development in the future, and its each light splitting wavelength out, can carry out wavelength conversion, therefore many to the quantitative requirement of wavelength shifter.In addition, from the angle of method, the method for design based on the first node structure is special circumstances (transforming to after light splitting on identical wavelength) of the second node structure in fact, so the present invention adopts the second node structure.

2.2 network link

Between two network nodes, connected by the contrary one-way optical fiber of a pair of transmission direction.Article two, optical fiber has identical wavelength set, and number of wavelengths is | W|.Article two, optical fiber is that physical link separates, and in the use of wavelength, and separate in the transmission of data, be independent of each other.

2.3 basic structure

For given physical topology G _p(V, L, W), according to following steps structure multilayer auxiliary view.

(1) by each node v _i∈ V, i=1,2 ..., | V|, copies | W| time, is labeled as respectively

be called wavelength node.There is identical ID by the duplicated all wavelengths node of same node, be its physical node ID.If from node v _ito node v _jthere is an oriented physical link l _ij, so for all w=1,2 ... | W|, from wavelength node

to wavelength node

increase a link

be called wavelength span, every wavelength span is corresponding to a wavelength in its place physical link.So just, constructed wavelength hierarchical diagram, the topology that the wavelength node that wherein each wavelength is corresponding and wavelength span form, is called wavelength plane.For example, (suppose that every physical link medium wave long number is 2) as shown in Figure 8 according to the wavelength hierarchical diagram of physical topology structure in Fig. 6.

(2) by each node v _i∈ V, i=1,2 ..., | V| copies one time, is designated v ' _i, be called logical node.Logical node is connected with winding-up for receiving, and can be understood as ip router node.If at WDM layer, there is one from node v _ito node v _jlight path, increase so one from node v ' _ito node v ' _jvirtual link, be called logical links (logical links is light path hereinafter), the bandwidth of logical links is the capacity (supposing that all light paths are all single wavelength channels) of a wavelength.The topology being made up of logical node and logical links is called logical topology.Logical topology and wavelength hierarchical diagram are combined and just formed basic multilayer auxiliary view.Or take the topology of Fig. 6 as example, suppose with wavelength X ₂create one from node v ₂to node v ₄light path, light path is through intermediate node v ₃.By in wavelength hierarchical diagram

and

wavelength span be labeled as and use, in logical topology, increase v ' ₂to v ' ₄logical links, the multilayer auxiliary view obtaining is as shown in Figure 9.

2.4 optical transceiver number constraints

When business is carried out to Traffic grooming, sometimes utilize existing logical links to can not find the route that can reach destination node, at this moment need newly-built light path.When each newly-built light path, light path source node need to consume an optical transmitter, and destination node consumes an optical receiver.Logical links, as the receiving node of business, need to record available light transmitter number and available light receiver number.As long as source, destination node have one not meet the demands, light path just can not be set up.For by the digitlization constraint of optical transceiver number, be converted into the content of graph theory, adopt the conceptual description optical transceiver number constraint of receiving link.For arbitrary node v _i∈ V, i=1,2 ..., | V|, increases v ' _iarrive

and

to v ' _ireceiving link.

Take Fig. 9 as example, suppose that each Nodes optical receiver number and optical transmitter number are 2, due to v ₂to v ₄a newly-built light path, so v ₂place's available light transmitter number subtracts one, v ₄place's available light receiver number subtracts one.The multilayer auxiliary view obtaining so as shown in figure 10, the wherein other numeral of logical node, expression available light transmitter number above, expression available light receiver number below.

2.5 wavelength conversion capability constraints

The present invention considers sparse part wavelength conversion capability constraint, and this constraint can solve by improving multilayer auxiliary view.

For arbitrary node v _i∈ V, its wavelength conversion range is r, increases so w1=1,2 ..., | W| arrives

w2=max{1, w1-r} ... w1-1, w1+1 ... min{|W|, the virtual link of w1+r}, is called wavelength transfer link.

Introduce after wavelength conversion capability, the structure of light path and light tree changes to some extent.

(1) light path

Light path in general sense, in order to meet wavelength continuity constraint, requires each wavelength span of light path process to have identical wavelength, and light path is made up of one group of wavelength span with identical wavelength.In the time of a newly-built light path, only need in certain wavelength plane, find the route of linked source, destination node.Considering that each wavelength span of light path process can use different wavelength after wavelength conversion capability, in the time of a newly-built light path, be no longer just route in certain wavelength plane, but on multilayer auxiliary view route.The ordered set that now light path is made up of wavelength span and wavelength transfer link.

(2) light tree

Introduce after wavelength conversion, the each node on light tree is wavelength node, and father node may be wavelength span or wavelength transfer link to the link of child nodes.

2.6 link cost

2.6.1 logical links

Each logical links is corresponding a light path of WDM layer all, and the capacity of logical links bandwidth is exactly the bandwidth capacity of light path.Article one, the loading condition of logical links can have multiple balancing method, and the quantity of the LSP for example carrying on this logical links, dedicated bandwidth accounts for the ratio of total bandwidth etc.Consider the bandwidth difference that different business is asked, be simply difficult to the loading condition of reflected optical path with business number, so select dedicated bandwidth to account for the ratio of total bandwidth as the standard of a logical links loading condition of measurement.To account for the ratio of total bandwidth higher for dedicated bandwidth, and the load of this logical links is heavier, in the time of routing, will avoid as much as possible this link, so will be the link cost that this link setting is larger.In like manner, for dedicated bandwidth accounts for the lower less link cost of link setting of ratio of total bandwidth.

Make b _t, b _w, b _p, b _rthe total bandwidth, bandwidth of operation, protection bandwidth and the user's bandwidth on demand that represent respectively this logical links, the link cost of this logical links is suc as formula shown in 2.1 so.

$W_{\mathrm{ll}}=\left\{\begin{array}{cc}\&infin;& b_t-b_w-b_p<b_r\\ (1+\frac{b_w+b_p}{b_t})\&times;{\mathrm{\&alpha;}}_{\mathrm{ll}}& b_t-b_w-b_p\&GreaterEqual;b_r\end{array}\right.---(2.1)$

2.6.2 receive link

Receiving the link cost of link is service condition for reflecting this Nodes optical transmitter and optical receiver.For certain node, when this node is during as the source node of new light path, consume optical transmitter of this Nodes; When this node is during as destination node, consume an optical receiver, so separate when the service condition of optical transmitter and optical receiver for certain node.

Make t _t, r _t, t _a, r _arepresent respectively the total optical transmitter number of this Nodes, total optical receiver number, available light transmitter number and available light receiver number, the link cost from logical node corresponding to this node to the receiving link of the corresponding all wavelengths node of this node is suc as formula shown in 2.2 so.

$W_{\mathrm{al}}=\left\{\begin{array}{cc}\&infin;& t_a=t_t\\ (1+\frac{t_t-t_a}{t_t})\&times;{\mathrm{\&alpha;}}_{\mathrm{al}}& t_a<t_t\end{array}\right.---\left(2.2\right)$

The corresponding all wavelengths node of this node to the link cost of the receiving link of its logical node suc as formula shown in 2.3.

$W_{\mathrm{al}}=\left\{\begin{array}{cc}\&infin;& r_a=r_t\\ (1+\frac{r_t-r_a}{r_t})\&times;{\mathrm{\&alpha;}}_{\mathrm{al}}& r_a<r_t\end{array}\right.---(2.3)$

2.6.3 wavelength span

The link cost of wavelength span is loading condition for reflecting the physical link under this wavelength span.The loading condition of physical link can be with weighing by the ratio that number of wavelengths accounts for total number of wavelengths.Wavelength span has four kinds of use states: do not use, be used to build light path, be used to build light tree, be used to protection.

Make w _w, w _poperating wave long number and protection number of wavelengths in the affiliated physical link of this wavelength span respectively, if this wavelength span is used, its link cost is ∞ so, otherwise its link cost is suc as formula shown in 2.4.

$W_{\mathrm{wll}}=\left\{\begin{array}{cc}\&infin;& w_w+w_p=\left|W\right|\\ (1+\frac{w_w+w_p}{\left|W\right|})\&times;{\mathrm{\&alpha;}}_{\mathrm{wll}}& w_w+w_p<\left|W\right|\end{array}\right.---(2.4)$

3 dedicated multi-layered protection algorithms of multicast based on subtree

3.1 case study

In the time that physical link breaks down, can make a lot of business impaired, in order to reduce the quantity of impaired business, can pass through two kinds of mode processing:

(1) reduce as far as possible impaired subtree, require through the subtree of this physical link few as much as possible.From the angle of the whole network, require to make as much as possible the load balancing of physical link in the time of newly-built subtree, namely on every physical link, the use of operation wavelength wants balanced, and this method by being the link cost realization that each receiving link and wavelength span setting can rationally reflected load situations in multiple constraint multicast route MRMC algorithm.

(2) set when impaired when a light, reduce as much as possible affected business, the business that uses this subtree to dredge is few as much as possible.From the angle of the whole network, require in the time of the Traffic grooming carrying out based on subtree, make as much as possible the load balancing of each subtree, this method realizes by cost that can rationally reflected load situation for subtree setting in the multicast service amount based on subtree is dredged SMTG algorithm.

3.2 arthmetic statement

The basic thought of the method is: first newly arrived multicast service request is carried out to Traffic grooming; obtain work multicast forest; secondly set up for service request the protection multicast forest separating with work multicast forest physical link, the subtree of the operating load of finally attaching most importance to provides the protection of WDM layer.

Two, the dedicated multi-layered guard method of the clean culture based on load balancing in optical-fiber network of the present invention, comprises the steps:

Step (1), set up work multicast forest

Setting up work multicast forest is exactly the process of carrying out Traffic grooming for multicast request in fact, adopts multicast service amount congestion relief algorithm for asking to set up work multicast forest; If multicast service amount congestion relief algorithm is dredged unsuccessfully, algorithm finishes so.

Step (2), foundation protection multicast forest

It is that physical link separates that protection multicast forest requires with work multicast forest;

The physical link of step (2.1) light path separates

Wavelength span on each physical link of light path process is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

The physical link of step (2.2) subtree separates

Setting up work multicast forest for request, in the time using a certain stalk tree to dredge, not 100% if dredge availability factor, the business of carrying on some link in subtree so and this request are irrelevant, that is to say in the time of these link occurs fault, do not affect the operation of this business; So, in the time that the physical link that subtree is set separates, be not wavelength span on the physical link of simple subtree process, be set to ∞ through the light path of these wavelength spans and the cost of subtree.The step that physical link separation is set is as follows:

Step (2.2.1), search the destination node of dredging by this subtree;

Step (2.2.2), start to recall light tree along the opposite direction of business data flow from destination node, the wavelength span of these destination node business data flow processes dredged in record;

Step (2.2.3), obtain its corresponding physical link according to these wavelength spans, wavelength span on these physical links is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

For example, in Figure 11, the destination node set { v of light tree ₄, v ₅, v ₆, v ₇, v ₈, suppose destination node v in request ₆, v ₇and v ₈use this light tree to dredge, work as so v ₁→ v ₂, v ₂→ v ₃and v ₃→ v ₄physical link while breaking down, not traffic affecting normal transmission, so in the time that the physical link that this subtree is set separates, only need to arrange v ₁→ v ₈, v ₁→ v ₃, v ₃→ v ₆and v ₃→ v ₇this four edges physical link separates;

The method separating with this set subtree physical link, can reduce the number that creates wavelength span, light path and the subtree that can not be used because physical link separates while protecting multicast forest effectively, reduces and dredges probability of failure;

After being provided with and separating with the physical link of the tree of working with said method, utilize multicast service amount congestion relief algorithm to set up protection multicast forest for request, if protection multicast forest creates unsuccessfully, discharge so the resource taking in work multicast forest, algorithm is failed, end.

Step (3), protection WDM layer

The protection of WDM layer is divided into two classes: the protection of the protection of counterweight operating load light path and counterweight operating load subtree;

The protection of step (3.1) counterweight operating load light path

The operating load of light path is different from the load of light path, and operating load refers to that bandwidth of operation accounts for the ratio of light path total bandwidth; When the operating load of light path has exceeded the threshold value of specifying

time, be called heavy operating load light path, provide the protection of WDM layer at WDM layer for it; Here adopt path protection, the light path of the operating load of attaching most importance to provides the protection of WDM layer; Along with leaving away of business, originally provided that the load of the working light path of WDM layer protection may become lower than threshold value

if now delete its protection protection road, may have again a new business to use this light path to make its load exceed threshold value so at once

this just can introduce jitter problem; So another threshold value is set here

when providing its load of working light path of WDM layer protection lower than threshold value

time just delete its protection road;

When having set up for service request after working LSP and protection LSP, check successively working LSP each logical links (every logical links all corresponding a light path) of process, if its load has exceeded the threshold value of specifying

and the protection of WDM layer is not provided, and for this light path creates a protection light path, protection light path need to separate with its physical link so.The source node that makes this heavy operating load light path is v _a, destination node is v _b, concrete steps are as follows:

Step (3.1.1), link cost is set

The link cost of the corresponding all wavelengths link of physical link of heavy operating load light path process is set to ∞; The link cost of all logical links is set to ∞; The link cost of all the other wavelength spans is set according to formula 2.4; According to formula 2.2, v ' is set _aall go out edge joint receive the link cost of link; According to formula 2.3, v ' is set _ball enter edge joint receive the link cost of link; All the other receive the link cost of link to be set to ∞;

Step (3.1.2), pathfinding

Step (3.1.2.1), with dijkstra's algorithm calculate one connect v ' _aand v ' _bthe path of Least-cost, judge whether pathfinding success;

Step (3.1.2.2) is if failed, and WDM layer is protected unsuccessfully, and algorithm finishes;

Step (3.1.2.3), if this heavy operating load light path is labeled as " WDM layer is protected " state by success, continues execution step (3.1.3);

Step (3.1.3), Resources allocation

Protection light path source node place available light transmitter number subtracts one; Light path destination node place available light receiver number subtracts one; Each wavelength span use state of protection road process is set to " being used to protection ";

The protection of step (3.2) counterweight operating load subtree

The protection of counterweight operating load subtree refers to that the load of working as subtree is higher than the threshold value of specifying

time, adopt multicast protection algorithm for it provides the protection of WDM layer, if protected successfully, this subtree or light path are labeled as to " protection of WDM layer " state, otherwise, do not process.

Step (4), business are left away

In the time that business is left away, need to discharge the resource that its work multicast forest and protection multicast forest take, concrete steps are as follows:

Step (4.1) discharges the bandwidth taking in work multicast forest and the each light path of protection multicast forest successively;

Step (4.2) for WDM layer protection is provided but its operating load lower than threshold value

light path, delete its protection road, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of protection road process is set is " not using ";

Step (4.3), for the light path that dedicated bandwidth is 0, is deleted this light path: the service condition that each wavelength span of light path process is set is " not using "; Light path source node place optical transmitter number adds one; Destination node place optical receiver number adds one;

Step (4.4) discharges the bandwidth taking on work multicast forest and the each light tree of protection multicast forest successively;

Step (4.5) has discharged after bandwidth, for WDM layer protection is provided but its operating load lower than threshold value

light tree, delete all protections sections of this light tree, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of each protection section process is set is " not use ";

Step (4.6), for the light tree that dedicated bandwidth is 0, is deleted this light tree: the service condition that each wavelength span of light tree process is set is " not using "; Light path source node place optical transmitter number adds one; All destination nodes place optical receiver number adds one.

Claims (1)

1. the dedicated multi-layered guard method of the multicast based on subtree in WDM optical-fiber network, wherein WDM is wavelength division multiplexing, it is characterized in that: comprise the steps:

Step (1), set up work multicast forest

Adopt SMTG algorithm to set up work multicast forest for request, SMTG algorithm is multicast service amount congestion relief algorithm; If SMTG algorithm is dredged unsuccessfully, algorithm finishes so;

Step (2), foundation protection multicast forest

It is that physical link separates that protection multicast forest requires with work multicast forest;

The physical link of step (2.1), light path separates

Wavelength span on each physical link of light path process is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

The physical link of step (2.2), subtree separates

Step (2.2.1), search the destination node of dredging by this subtree;

Step (2.2.2), start to recall light tree along the opposite direction of business data flow from destination node, the wavelength span of these destination node business data flow processes dredged in record;

Step (2.2.3), obtain its corresponding physical link according to these wavelength spans, wavelength span on these physical links is set, is set to ∞ through the light path of these wavelength spans and the cost of subtree;

After being provided with and separating with the physical link of the tree of working with said method, utilize SMTG algorithm to set up protection multicast forest for request, if protection multicast forest creates unsuccessfully, discharge so the resource taking in work multicast forest, algorithm is failed, end;

Step (3), protection WDM layer

The protection of WDM layer is divided into two classes: the protection of the protection of counterweight operating load light path and counterweight operating load subtree;

The protection of step (3.1), counterweight operating load light path

When having set up for service request after working LSP and protection LSP, wherein LSP is label switched path, check successively working LSP each logical links of process, all corresponding light paths of every logical links, if its load has exceeded the threshold value of specifying

and the protection of WDM layer is not provided, and for this light path creates a protection light path, protection light path need to separate with its physical link so; The source node that makes this heavy operating load light path is v _a, destination node is v _b, concrete steps are as follows:

Step (3.1.1), link cost is set

The link cost of the corresponding all wavelengths link of physical link of heavy operating load light path process is set to ∞; The link cost of all logical links is set to ∞:

According to formula $W_{\mathrm{wll}}=\left\{\begin{array}{cc}\&infin;& w_w+w_p=\left|W\right|\\ (1+\frac{w_w+w_p}{\left|W\right|})\&times;{\mathrm{\&alpha;}}_{\mathrm{wll}}& w_w+w_p<\left|W\right|\end{array}\right.$ The link cost W of all the other wavelength spans is set _wll;

Wherein: w _w, w _poperating wave long number and protection number of wavelengths in the affiliated physical link of this wavelength span respectively, | W| represents the number of wavelengths of every physical link;

According to formula $W_{\mathrm{al}}=\left\{\begin{array}{cc}\&infin;& t_a=t_t\\ (1+\frac{t_t-t_a}{t_t})\&times;{\mathrm{\&alpha;}}_{\mathrm{al}}& t_a<t_t\end{array}\right.$ V ' is set _aall go out edge joint receive the link cost W of link _al, wherein v ' _av _acorresponding logical node;

According to formula $W_{\mathrm{al}}=\left\{\begin{array}{cc}\&infin;& r_a=r_t\\ (1+\frac{r_t-r_a}{r_t})\&times;{\mathrm{\&alpha;}}_{\mathrm{al}}& r_a<r_t\end{array}\right.$ V ' is set _ball enter edge joint receive the link cost W of link _al, wherein v ' _bv _bcorresponding logical node;

Wherein: t _t, r _t, t _a, r _arepresent respectively the total optical transmitter number of this Nodes, total optical receiver number, available light transmitter number and available light receiver number;

All the other receive the link cost of link to be set to ∞:

Step (3.1.2), pathfinding

Step (3.1.2.1), with dijkstra's algorithm calculate one connect v ' _aand v ' _bthe path of Least-cost, judge whether pathfinding success;

Step (3.1.2.2) is if failed, and WDM layer is protected unsuccessfully, and algorithm finishes;

Step (3.1.2.3), if this heavy operating load light path is labeled as " WDM layer is protected " state by success, continues step (3);

Step (3.1.3), Resources allocation

Protection light path source node place available light transmitter number subtracts one; Light path destination node place available light receiver number subtracts one; Each wavelength span use state of protection road process is set to " being used to protection ";

The protection of step (3.2), counterweight operating load subtree

The protection of counterweight operating load subtree refers to that the load of working as subtree is higher than the threshold value of specifying

time, adopt multicast shared segment protection MSSP algorithm for it provides the protection of WDM layer, if protected successfully, this subtree or light path are labeled as to " protection of WDM layer " state, otherwise, do not process;

Step (4), business are left away

Step (4.1), discharge the bandwidth taking in work multicast forest and protection multicast forest each light path successively;

Step (4.2), for WDM layer protection is provided but its operating load lower than threshold value

light path, delete its protection road, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of protection road process is set is " not using ";

Step (4.3), for the light path that dedicated bandwidth is 0, delete this light path: the service condition that each wavelength span of light path process is set is " do not use "; Light path source node place optical transmitter number adds one; Destination node place optical receiver number adds one;

Step (4.4), discharge the bandwidth taking on the each light tree of work multicast forest and protection multicast forest successively;

Step (4.5), discharged after bandwidth, for the protection of WDM layer is provided but its operating load lower than threshold value

light tree, delete all protections sections of this light tree, be masked as " WDM layer is not protected " state, the service condition that each wavelength span of each protection section process is set is " not use ";

Step (4.6), for dedicated bandwidth is 0 light tree, delete this light tree: the service condition that each wavelength span of light tree process is set is " not using "; Light path source node place optical transmitter number adds one; All destination nodes place optical receiver number adds one.

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