CN103312608A - Satellite network routing algorithm based on traffic engineering - Google Patents

Abstract

The invention discloses a satellite network routing algorithm based on traffic engineering. The method comprises the following steps of obtaining the topological graph of a current LEO satellite constellation network, and calculating the initial weights of all satellite links in the topological graph; calculating probable shortest paths of all S-D nodes according to a shortest path algorithm, and writing all shortest paths into a path set; adjusting weights to obtain the final weights of the links in the topological graph; and calculating a shortest path between requested target S-D nodes according to the shortest path algorithm. Via the design, the satellite route selection has the characteristics of balance and high effectiveness. In a route selection process, balance can be realized through network throughput; when the balance is higher, the network throughput is higher, otherwise the throughput is lower; the high effectiveness is represented by a bandwidth rejection rate; when the route successful times are more, the received bandwidth request are more, and the effectiveness is higher; otherwise, the effectiveness is lower.

Description

A kind of satellite network routing algorithm based on traffic engineering

Technical field

The present invention relates to the satellite routing algorithm, relate in particular to a kind of satellite network routing algorithm based on traffic engineering.Relate to patent H04 electrical communication technology H04W cordless communication network H04W40/00 communication route or communication path and search H04W40/02 communication route or Path selection, for example, based on power or the shortest path route.

Background technology

Between the second time data link layer and three-layer network layer, it can not individualism, need to combine with IP network or atm network in TCP/IP protocol suite for the multiprotocol label switching (mpls) technology.As shown in Figure 1, the MPLS network consists of a mpls domain by a plurality of MPLS routers, and the router in the territory is called LSR (LSR), and the router on border, territory is called label edge router (LER).When packet arrives the LER of mpls domain, the information that meeting provides according to packet, packet is carried out forwarding equivalence class (FEC) definition, then set up suitable label switched path (LSP) according to FEC, all nodes (router) on LSP are FEC Resources allocation bandwidth.After data began transmission, router was transmitted according to the label of packet on the LSP path.

The MPLS correlative study of satellite network became an a new direction of the research of satellite network after 2003, and obtained some achievements in research in association area.For Satellite Network Routing Algorithms, mainly formed three kinds of strategies, be respectively virtual topology, the dummy node strategy relevant with topology.Because satellite node is in the high-speed motion constantly, the satellite network topology has time variation.Virtual topology is divided into a lot of timeslices with satellite network, thinks that topology does not change in a timeslice.Dummy node is divided into a plurality of zones with the earth, and after the sub-satellite track of satellite arrived certain zone, this satellite just occupied this regional address.Strategy and relevant, relevant according to the topology design algorithm of concrete satellite network topology that topology is relevant.

Summary of the invention

The present invention is directed to above problem, proposed a kind of satellite network routing algorithm based on traffic engineering, have following steps:

-when having label switched path to set up request, inquire about satellite ephemeris, obtain the topological diagram of current LEO Satellite Constellation Networks, be that each satellite in the described Constellation Network is set numbering; Calculate the initial weight of all satellite links in the described topological diagram; Initialization critical path collection is empty;

-press shortest path first, calculate the shortest path that the possible link between the whole S-D nodes of described topological diagram consists of, all shortest paths that obtain are write described critical path collection;

The described path of-check concentrates S-D node corresponding to each shortest path whether to set up the S-D node matching of request with label switched path, if coupling increases the weight of described shortest path respective links, if do not mate the weight that then reduces respective links in the described shortest path, obtain the final weights of described topological diagram link;

-press shortest path first, calculate the shortest path between the target S-D node of the label switched path request of setting up; By this shortest path the node of process distribute the bandwidth ask, prepare the transmission of data.

Described step "-when having label switched path to set up request, the inquiry satellite ephemeris .... initialization critical path collection is empty; " specifically comprise:

The numbering of satellite laterally is N orbital plane since 0 in orbital plane and the track, vertically for every orbital plane M satellite is arranged; The intersatellite link that defines different orbital planes is defined as inter satellite link between rail, and ISL between rail, the intersatellite link of same orbital plane are defined as inter satellite link in the rail, ISL in the rail; The definition satellite is numbered (i, j), wherein

$\left\{\begin{array}{c}0\≤i\≤N-1,\\ 0\≤j\≤M-1\end{array}\right.;$

The initial weight of definition link is w ₀(u, v) is the function of remaining bandwidth and link existent time, and expression formula is as follows:

In the following formula, B _LeftBe current time, the maximum residual bandwidth in all links; T _LiveRepresent current time, the maximum of residue link existent time among the ISL between rail; t _Live(u, v) and b _Left(u, v) is respectively link existent time and the remaining bandwidth between node u and the v; Link between l (u, the v) representation node (u, v), λ ₁Be regulatory factor, be used for regulating remaining bandwidth to the contribution of weight;

Calculate the initial weight of every link according to following formula.

Set T _{Live-threshold}Be the threshold value of every link remaining time, when remaining time of link during less than this threshold value, directly delete this link from the topological diagram of described LEO Satellite Constellation Networks.

Described step: "-press shortest path first ... all shortest paths that will obtain write described critical path collection " specifically comprise the steps:

At first, according to shortest path first, obtain the shortest path during all s-d nodes (source-destination node) may be gathered in the described topological diagram, concentrate with the link in the shortest path and to critical path;

Then, a link of weights maximum according to shortest path first, recomputates shortest path in the deletion gained path; Incorporating the link in the gained shortest path into critical path concentrates;

Repeat above-mentioned steps, do not have shortest path until the number of gained shortest path satisfies between K or the S-D node, finally obtain critical path collection CriticalCollect.

If in the shortest path during all S-D nodes may be gathered at first by shortest path calculating topological diagram, do not obtain at least one shortest path, and current S-D node is not that label switched path is set up the S-D node of asking, then refuse label switched path and set up request, stop calculating, discharge the resource of application in calculating.

Described " the described path of-check concentrates S-D node corresponding to each shortest path whether to set up the S-D node matching of request with label switched path .... " step specifically comprises:

The crucial degree of definition link (u, v) is δ (u, v).So, the dynamic adjustment weight w of definition link (u, v) ₁(u, v)=λ ₂δ (u, v), wherein λ ₂Be regulatory factor, link key degree δ (u, v) depends on network configuration;

According to the critical path collection CriticalCollect that obtains and dynamically adjust weight w ₁, each the bar link weight repeated root in the network is adjusted according to following formula:

$w(u,v)=\left\{\begin{array}{c}{w}_0(u,v)+w_1(u,v),s^{\′}{d}^{\′}\∈\mathrm{sd}\\ w_0(u,v)-w_1(u,v),s^{\′}{d}^{\′}\∉\mathrm{sd}\end{array}\right.$

Wherein, sd is source-destination node that current LSP asks, and s'd' is current source-destination node of calculating.

By above-mentioned design, so that the satellite Route Selection has following characteristics: harmony and high-efficiency.In routing procedure, harmony can embody by network throughput, and harmony is higher, and then network throughput is larger, otherwise throughput is then little; High-efficiency then represents by the bandwidth reject rate, and the route number of success is more, and the bandwidth request of acceptance is more, and then validity is higher; Otherwise then validity is less.Of the present invention having a extensive future can be widely used in the Route Selection of Communication in China satellite system Satellite-satellite, can also be applied to the Route Selection of sky Incorporate network simultaneously, has high economic benefit and social benefit.Utilize satellite method for routing of the present invention, higher network throughput and the traffic, lower bandwidth reject rate are arranged, can greatly improve the payload of satellite network.

Description of drawings

Technical scheme for clearer explanation embodiments of the invention or prior art, the below will do one to the accompanying drawing of required use in embodiment or the description of the Prior Art and introduce simply, apparently, accompanying drawing in the following describes only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.

Fig. 1 is satellite MPLS network topology schematic diagram of the present invention

Fig. 2 is constellation network plane schematic diagram of the present invention

Embodiment

For the purpose, technical scheme and the advantage that make embodiments of the invention is clearer, below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is known complete description:

Shown in Fig. 1-2: mainly comprise the steps:

Initialization step:

When having label switching path LSP to set up request, inquire about current (when calculating the shortest path of all S-D, when calculating the shortest path of a pair of S-D, what calculated this moment is " current " S-D node) satellite ephemeris, obtain the topological diagram of current LEO MEO/LEO Satellite Constellation Network, as shown in Figure 1.

For each satellite in the described Constellation Network is set numbering, as shown in Figure 2: the satellite in the topological diagram is converted to constellation network plane schematic diagram, described satellite can and be arranged by following scheme name, the numbering of satellite is since 0 in orbital plane and the track, be N orbital plane laterally, vertically for each orbital plane M satellite arranged.The intersatellite link that defines different orbital planes is defined as inter satellite link between rail (ISL between rail), and the intersatellite link of same orbital plane is defined as inter satellite link in the rail (ISL in the rail).The definition satellite is numbered (i, j), wherein

$\left\{\begin{array}{c}0\≤i\≤N-1,\\ 0\≤j\≤M-1\end{array}.\right.$

Calculate the initial weight of all satellite links in the described topological diagram: the initial weight of link is to be determined by the residual flow between current network topology and link in the present invention.The initial weight of definition link is w ₀(u, v) is defined as the function of remaining bandwidth and link existent time with it.

(1) in the formula, w ₀(u, v) is the initial weight cost of node u to node v.B _LeftBe current time, the maximum residual bandwidth in all links.T _LiveRepresent current time, the maximum of residue link existent time among the ISL between rail.t _Live(u, v) and b _Left(u, v) is respectively link existent time and the remaining bandwidth between node u and the v.Link between l (u, the v) representation node (u, v), λ ₁Be regulatory factor, be used for regulating remaining bandwidth to the contribution of weight.

Definition B _Left/ b _LeftThe reason of (u, v) is that the link weight is affected by remaining bandwidth.The link that remaining bandwidth is larger illustrates that network condition is better, can hold more flow.For ISL between rail, the link initial weight is T _Live/ t _Live(u, v) and B _Left/ b _LeftThe impact of (u, v) two aspects is that the life span of ISL between rail is considered to the link weight.And for ISL in the rail, owing to not disconnecting between the link, therefore link existent time is not counted.

Further, consider, as bandwidth on demand b _ReqWhen arriving label edge router (LER), in order to simplify link calculation, remaining bandwidth in the network is not satisfied b _ReqLink circuit deleting, avoid the adjustment of link calculation and link weight, reduce to calculate.In practical communication, for the too short link of link existent time, just can be invalid because this link is very fast.Pretending is a better execution mode, and the present invention is that every link arranges a threshold T remaining time _{Live-threshold}, when link during less than this threshold value, direct this link of deletion from topology.The meaning that this threshold value is set is, avoided the LSP that calculates too short effective time through the path that this link causes, the meaningless path that is caused by link switching.

Set a critical path collection CriticalCollect, and this path collection of initialization is empty.

Calculate the shortest path step:

According to shortest path first, calculate the shortest path that all the possibility link consists of between the S-D node (source-destination node) in the described topological diagram: specific algorithm is as follows:

At first, according to shortest path first, obtain the shortest path during all S-D nodes (source-destination node) may be gathered in the described topological diagram, concentrate with the link in the shortest path and to critical path;

Then, a link of weights maximum according to shortest path first, recomputates shortest path in the deletion gained path; Incorporating the link in the gained shortest path into critical path concentrates;

Repeat above-mentioned steps, until the number of gained shortest path satisfies K, be generally 3～5, belong to empirical value.Perhaps there is not shortest path between the S-D node, finally obtains critical path collection CriticalCollect.

Further, if in the shortest path during all S-D nodes may be gathered at first by shortest path calculating topological diagram, do not obtain at least one shortest path, and current S-D node is not that label switched path is set up the S-D node of asking, then refuse label switched path and set up request, stop calculating, discharge the resource of application in calculating.

The weight regulating step:

Critical path collection CriticalCollect according to above-mentioned steps obtains will gather according to this afterwards, dynamically adjusts the weight of each link in the network.The crucial degree of definition link (u, v) is δ (u, v).So, the dynamic adjustment weight of definition link (u, v)

w ₁(u,v)＝λ ₂δ(u,v) （2）

λ wherein ₂With λ mentioned above ₁Be regulatory factor, regulatory factor is relevant with network topology, link character and weighting function, can determine by emulation, generally can get 1～3.Link key degree δ (u, v) depends on network configuration, for different Linktypes, such as GEO-LEO link or LEO-LEO link different crucial degree can be set.

Determine final route.According to the critical path collection CriticalCollect that obtains and dynamically adjust weight w ₁, each the bar link weight repeated root in the network is changed according to formula (3).

$w(u,v)=\left\{\begin{array}{c}{w}_0(u,v)+w_1(u,v),s^{\′}{d}^{\′}\∈\mathrm{sd}\\ w_0(u,v)-w_1(u,v),s^{\′}{d}^{\′}\∉\mathrm{sd}\end{array}\right.---\left(3\right)$

Wherein, sd is source-destination node that current LSP asks, and s'd' is current source-destination node of calculating.The implication of following formula is, if the link (u, v) of current calculating, its source node is s, and destination node is d, so then increases the weight of this link, otherwise just reduces its weight.After processing like this, with regard to so that the weight of each link adjust.This is so that current LSP when selecting paths, can consider following selection.

After obtaining the final weights of described topological diagram link (adjust by formula 3 after), press shortest path first, calculate label switched path and set up shortest path between the target S-D node of asking; By this shortest path the node of process distribute the bandwidth ask, prepare the transmission of data, finish whole routing algorithm.

The above; only be the better embodiment of the present invention; but protection scope of the present invention is not limited to this; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses; be equal to replacement or change according to technical scheme of the present invention and inventive concept thereof, all should be encompassed within protection scope of the present invention.

Claims (6)

1. satellite network routing algorithm based on traffic engineering has following steps:

-when having label switched path to set up request, inquire about satellite ephemeris, obtain the topological diagram of current LEO Satellite Constellation Networks, be that each satellite in the described Constellation Network is set numbering; Calculate the initial weight of all satellite links in the described topological diagram; Initialization critical path collection is empty;

-press shortest path first, calculate the shortest path that the possible link between the whole S-D nodes of described topological diagram consists of, all shortest paths that obtain are write described critical path collection;

The described path of-check concentrates S-D node corresponding to each shortest path whether to set up the S-D node matching of request with label switched path, if coupling increases the weight of described shortest path respective links, if do not mate the weight that then reduces respective links in the described shortest path, obtain the final weights of described topological diagram link;

-press shortest path first, calculate the shortest path between the target S-D node of the label switched path request of setting up; By this shortest path the node of process distribute the bandwidth ask, prepare the transmission of data.

2. a kind of satellite network routing algorithm based on traffic engineering according to claim 1 is further characterized in that: described step "-when having label switched path to set up request, the inquiry satellite ephemeris .... initialization critical path collection be sky; " specifically comprise:

The numbering of satellite laterally is N orbital plane since 0 in orbital plane and the track, vertically for every orbital plane M satellite is arranged; The intersatellite link that defines different orbital planes is defined as inter satellite link between rail, and ISL between rail, the intersatellite link of same orbital plane are defined as inter satellite link in the rail, ISL in the rail; The definition satellite is numbered (i, j), wherein

$\left\{\begin{array}{c}0\≤i\≤N-1,\\ 0\≤j\≤M-1\end{array};\right.$

The initial weight of definition link is w ₀(u, v) is the function of remaining bandwidth and link existent time, and expression formula is as follows:

In the following formula, B _LeftBe current time, the maximum residual bandwidth in all links; T _LiveRepresent current time, the maximum of residue link existent time among the ISL between rail; t _Live(u, v) and b _Left(u, v) is respectively link existent time and the remaining bandwidth between node u and the v; Link between l (u, the v) representation node (u, v), λ ₁Be regulatory factor, be used for regulating remaining bandwidth to the contribution of weight;

Calculate the initial weight of every link according to following formula.

3. a kind of satellite network routing algorithm based on traffic engineering according to claim 2 is further characterized in that: set T _{Live-threshold}Be the threshold value of every link remaining time, when remaining time of link during less than this threshold value, directly delete this link from the topological diagram of described LEO Satellite Constellation Networks.

4. according to the described a kind of satellite network routing algorithm based on traffic engineering of above-mentioned any one claim, be further characterized in that described step: "-press shortest path first ... all shortest paths that will obtain write described critical path collection " specifically comprise the steps:

At first, according to shortest path first, obtain the shortest path during all s-d nodes (source-destination node) may be gathered in the described topological diagram, concentrate with the link in the shortest path and to critical path;

Then, a link of weights maximum according to shortest path first, recomputates shortest path in the deletion gained path; Incorporating the link in the gained shortest path into critical path concentrates;

Repeat above-mentioned steps, do not have shortest path until the number of gained shortest path satisfies between K or the S-D node, obtain critical path collection CriticalCollect.

5. a kind of satellite network routing algorithm based on traffic engineering according to claim 4, be further characterized in that: if in the shortest path during all S-D nodes may be gathered at first by shortest path calculating topological diagram, do not obtain at least one shortest path, and current S-D node is not that label switched path is set up the S-D node of asking, then refuse label switched path and set up request, stop calculating, discharge the resource of application in calculating.

6. a kind of satellite network routing algorithm based on traffic engineering according to claim 2 is further characterized in that: described " the described path of-check concentrates S-D node corresponding to each shortest path whether to set up the S-D node matching of request with label switched path .... " step specifically comprises:

The crucial degree of definition link (u, v) is δ (u, v).So, the dynamic adjustment weight w of definition link (u, v) ₁(u, v)=λ ₂δ (u, v), wherein λ ₂Be regulatory factor, link key degree δ (u, v) depends on network configuration;

According to the critical path collection CriticalCollect that obtains and dynamically adjust weight w ₁, each the bar link weight repeated root in the network is adjusted according to following formula:

$w(u,v)=\left\{\begin{array}{c}{w}_0(u,v)+w_1(u,v),s^{\′}{d}^{\′}\∈\mathrm{sd}\\ w_0(u,v)-w_1(u,v),s^{\′}{d}^{\′}\∉\mathrm{sd}\end{array}\right.$

Wherein, sd is source-destination node that current LSP asks, and s'd' is current source-destination node of calculating.

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