CN1710885A - QoS multi-broadcast routing method based on Ant-like mobile agent - Google Patents

Abstract

Implementing mobile agent under network simulator NS2, the invention includes steps: (1) building network model; multicasting tree T(VT, ET) satisfies following conditions: time delay constraint delay(P(s, m)) less than and equal to D, Pm is a member of the set M; bandwidth constraint bandwidth(P(s, m)) larger than and equal to B, e is a member of the P(s, t), where P as route, s as source node, m as target node, D as maximal time delay, B as minimal bandwidth; (2) expanding NS2 in following four sides: 1, expansion of class i.e. mobile agent MA classifier is expanded in address classifier; 2, expansion of packet i.e. MA head is expanded in packet head of NS2; 3, expansion of node, i.e. special data packet including mobile agent is added in node structure of original NS2; 4, expansion of agent, i.e. implementation environment MAE of mobile agent is built and loaded to node.

Description

A kind of method of the QoS multicast route based on the Ant-Like mobile agent

Technical field

The present invention relates to a kind of method (MAMRQoS) of the QoS multicast route based on the Ant-Like mobile agent, belong to network technology, the communication technology, multimedia application technical field (implication of QoS is a service quality).

Background technology

Ant algorithm is a kind of simulated evolutionary algorithm based on population, through discovering in a large number, ant has the ability of seeking the shortest (optimum) path between ant cave and the food source, this ability be by its a kind of volatility secretion pheromones (Pheromone) of staying on the path of process realize that the intensity of pheromones is directly proportional on the probability of selecting this path on a road when ant advances and this paths.For shortest path, select its ant more and more, cause the plain accumulation of more information, attract more ant, thereby formed a kind of positive feedback, shortest path will be found by the most ants of very fast quilt like this, and the exchange of information between the ant individuality reaches the purpose of search food with mutual the cooperation.

AntNet is a kind of distributed self-adaption shortest path computational methods based on mobile Agent, originates from ant group algorithm famous in the bionics.The basic thought of AntNet is: any one node is a source node in the network, be destination node to a node of selecting at random at a certain time interval, distribute a mobile Agent and search for shortest path between two nodes for forward direction Agent, collect the record path state information simultaneously, Agent each intermediate node according to routing table in adjacent node the orientation probability ratio value or choose next-hop node with random fashion, write down the identifier of node simultaneously and from source node to hourage that this node experienced, repeat this process, until arriving destination node, after the forward direction Agent that arrives destination node produces one to Agent, and the information of collecting is all passed to this Agent wither away afterwards, move along the rightabout in same path to Agent the back, and with its information of carrying to orientation probable value in the routing table of node of process and hourage etc. parameter upgrade, and prove that by simulated experiment its performance is better than traditional link-state algorithm and distance vector algorithms, but this algorithm is only at the datagram transmission of doing one's best, do not have consideration to have the route computational problem of the real time data stream of quality of service requirement, have certain limitation.

Routing algorithm based on Agent is the application of artificial intelligence in network, and the algorithm that Appleby and Steward have proposed similar ant Agent at first can be used for network control such as route and load balance etc., but they do not provide the realization prototype.Based on distribution type QoS (service quality) route computing method of mobile Agent, this method adopts the mobile Agent search network, seeks the path of satisfying the QoS request, and behind the introducing mobile Agent, system has more flexibility and adaptability.

The ant route is a kind of routing algorithm of novelty, and it derives from the model of ant group hunting food in the biology.In the ant route, be referred to as Agents, the a group ant is used to explore the source node of appointment and the shortest path between the destination node, for a destination node, not to have a fixing next-hop node in routing table, but have a plurality of optional next-hop nodes, each candidate's next-hop node all has a probable value, is illustrated in to calculate the selecteed possibility of this candidate value under the shortest path situation.The probable value of these both candidate nodes equates when initial, in the running of algorithm, is upgraded by the ant of process bag at any time.For a pair of given source node and destination node, source node will produce the ant of some, send these ants bags according to it self route table items to network, and they will finish the task that network is sought the path of exploring.Ant can be remembered the path node of process, therefore when an ant arrives destination node, it can return source node along source path, and in the process of returning, ant gets used to changing according to following rule according to self-contained information state the routing table of each node of its process.The update rule of routing table be in the routing table of present node, increase ant from the probable value of that both candidate nodes, reduce the probable value of other both candidate nodes, the higher path of probable value always is preferred, increased the selection probability in this path so again, increasing ant will be followed this paths, further increased probable value, finally make more ant follow this paths, just because of this positive feedback loop, make a very fast appearance in best path, and when new best path of offered load change occurs, ant is approval and reinforcement rapidly, therefore the ant route is dynamic, adaptive, and have favorable expansibility and flexibility.

More than these restricted problems that solve QoS multicast route all of no use.

Summary of the invention

The objective of the invention is to solve the restricted problem of QoS multicast route, propose a kind of method of the QoS multicast route based on the Ant-Like mobile agent, solve constraints such as time delay, time delay vibration, broadband and loss rate in the real-time application with it.

Technical scheme of the present invention: the present invention provides a kind of method of the QoS multicast route based on the Ant-Like mobile agent, realizes mobile agent under network simulator NS2, it is characterized in that:

One, set up network model: multicast tree T (VT, ET) satisfy:

Delay constraint, delay (P (s, m))≤D, Pm ∈ M. (1)

Bandwidth constraint bandwidth (P (s, m)) 〉=B, e ∈ P (s, t) (2)

In the formula: the P delegated path, s represents source node, and m represents destination node, and D represents maximum delay, and B represents minimum broadband;

Two, NS2 is done the expansion of following four aspects:

1) expansion of class: expansion mobile agent MA grader in the address sort device;

2) packet expansion: expansion MA head in the packets headers of NS2;

3) expansion of node node: in the node node of original NS2 structure, increased a kind of special data newspaper that comprises mobile agent;

4) expansion of Agent: set up mobile agent execution environment MAE, and on node, load; Expansion comprises two parts: at first be the function that strengthens switcn_, make it can judge whether the Packet that receives is mobile agent; Next is to increase a MA grader of handling the mobile agent packet.

Advantage of the present invention: the success rate that has improved mobile agent acquisition shortest path; Solved the network equalize problem.

Description of drawings

Fig. 1 is the network model schematic diagram;

Fig. 2 sets up the network model flow chart;

Fig. 3 structural extended schematic diagram;

The expansion schematic diagram of Fig. 4 Node.

Embodiment

One, theoretical foundation:

The present invention has at first proposed the network model of the multicast route of multi-QoS constraint, the purpose of QoS multicast route is exactly to seek optimal path in the network that distributes, requirement is from source node, go through all destination nodes, and satisfy all constraints, reach the cost minimum or reach specific service level, QoS multicast routing issue is a np complete problem.

Network can be expressed as a weighted graph G=(V, E), wherein V represents set of node, E represents the communication link collection of connected node, | V| and | E| represents node number and the number of links in this network respectively.For being without loss of generality, only consider such class figure, promptly in such network, have only a link between a pair of node at most, the parameter in chain roadside can be used for describing the current state of this link.If (wherein s ∈ V is the source node of a multicast tree to T for s, M) expression multicast tree, and { V-{s}} is the end node or the leaf segment point set of this multicast tree to M , establishes R ⁺Be the arithmetic number collection.Here define two function: c (u, v) and d (u v), represents cost and time delay on the link l respectively, establish l=(u, v) ∈ E, then c (u, v):

D (u, v):

Wherein d (u has v) comprised the queuing, transmission and the propagation three part time delays that are grouped on node and the link, suppose P (u v) represent the paths from node u to node v, and multicast tree is T, should have following relationship so:

Time delay: be meant the time delay summation of link, be:

$\mathrm{delay}\left(P(s,m)\right)=\underset{l\∈P(s,m)}{\mathrm{\Σ}}d\left(l\right),m\∈M---(1-1)$

Broadband: be meant the minimum broadband value of link, be:

bandwidth(P(s，m))＝min{bandwidth(e)，e∈P(s，t)} (1-2)

Cost: the cost summation that is meant link:

$\cos t\left(T\right)=\underset{l\∈T}{\mathrm{\Σ}}c\left(l\right)$

The minimum multicast routing issue of the cost of time delay and bandwidth constraints, a given network G=(V, E), multicast source node s ∈ V, multicast group M { V-{s}}, time delay function d (u, v) ∈ R ⁺, cost function c (u, v) ∈ R ⁺, require to find one from s, connect the multicast tree T (V of all destination nodes _T, E _T) satisfy:

Delay constraint, delay (P (s, m))≤D, Pm ∈ M. (1)

Bandwidth constraint bandwidth (P (s, m)) 〉=B, e ∈ P (s, t) (2)

Cost constrains in satisfy condition (1), in the all-multicast tree of (2) two formulas, and T (V _T, E _T) cost cost (T) minimum.

Next is the method (MAMRQoS) that has proposed a kind of QoS multicast route based on the Ant-Like mobile agent, its main thought is according to the QoS service request, allow mobile Agent only satisfy the link moving of QoS demand along those at each node, search out the feasible path that satisfies the QoS request, and in node hop-by-hop record path information, in order to describe MAMRQoS better, being described property ground defines, and definition comprises routing table, link available bandwidth table, source path and path vector.

Two, embodiment

Realize that under NS2 mobile agent (Mobile Agents) is the research topic that develops rapidly in recent years, it has unique independence, intelligent and mobility is that a kind of brand-new model has been introduced in Distributed Calculation and network control.For making simulation softward can adapt to the multiple network environment, the expansion of the universal network emulation tool by maturation is developed, and should be a kind of efficient and reliable method, and first-selected common simulation instrument is the NS2 simulation softward.

1.Mobile the foundation of Agents model, as shown in Figure 1: set up model and realize mobile agent, this model can be simulated the behavior of true mobile agent, as the execution of preplanned mission, visit present node, active migration etc.

Set up network model: multicast tree T (V _T, E _T) satisfy:

Delay constraint, delay (P (s, m))≤D, Pm ∈ M. (1)

Bandwidth constraint bandwidth (P (s, m)) 〉=B, e ∈ P (s, t) (2)

In the formula: the P delegated path, s represents source node, and m represents destination node, and D represents maximum delay, and B represents minimum broadband.

Specifically set up the network model flow chart: utilize Matrix Formula p after the initialization as Fig. 2 _{T ' rs}Calculate all nodes that satisfy (1), (2) two formula conditions; Adjust parameter, calculate again, get all nodes that reach the cost minimum; Utilize all nodes that satisfy (1), (2) two formula condition cost minimums to generate multicast tree.

At last MAMRQoS is realized being described, the main false code of realization is as follows:

In QoSMRMA, realize by a simple mobile agent, the parameter of required automatic recurrence is preserved in each node supposition in the network, current address of living in (address) and current minimum cost (cost), after network topology is created, network id just determines that the renewal of minimum cost (cost) is to realize by proxy access node and the value of adjusting parameter b, so the main false code of algorithm can be expressed as:

Switch (control of main circulation)

The case initialization (tabulist, t)

tabulist＝{}；

The t=current time

L_min＝0；

home_node＝current_node.address；

The b=initial value;

break

Case search for forward (tabulist, current_node.address, s)

L_min＝Min(L_min，current_node.L_min)；

r＝current_node.address；

p _(s)=calculating p _{T, rs}

X＝(0.0，1.0)；

If (X＜p _(s)The s of) //is a neighbor node

Move on to node s;

else?p _(s)＝0

The value of L_min=calculation cost (cost)

end?if

break

Case adjusts parameter (b)

B=is assignment again; // assignment＞initial value again

r _T+1, r _T+1Parameter value with cost

break

Case returns

While (if tabulist is not empty)

s＝current_node；

Move to last node of tabulist

r＝current_node；

Upgrading P _{T ' rs}

R wherein _T+1Path vector, P _{T ' rs}The pheromones transformation matrices.

Above code utilogic figure represents as follows:

2. according to the functional requirement of mobile agent running environment, analyze the existing capability of NS2 and the Multicast Routing Algorithm characteristics of design feature and multi-QoS constraint, NS2 need do the expansion of following four aspects.

1) expansion of structure:

NS2 couples together object and variable in C++ and the Otcl bilingual by Tclcl, the component base of NS2 is a hierarchical structure, member is wherein all realized by two classes that are mutually related usually, one in C++, therefore another, just comprised the hierarchical structure of a C++ class and the hierarchical structure of an Otcl class among the NS2 in Otcl, the major function of member realizes that by the C++ program class among the Otcl then mainly provides the C++ object user oriented configuration interface.

As shown in Figure 3: in NS2, a node Node comprises an address sort device classifier_, type (multicast, clean culture and mobile agent MA) grader or a port grader dmux_, their effect is that the packet delivery of will come in is on correct link, agent or mobile agent, AddressClassifier expands to the class address, deriving class MAAddressClassifier, is the expansion to the address grader below: class SwitchClassifier:public Classifier{public:

SwitchClassifier()：mask_(:0)，shift_(0){}……

}class_switch_classifier；

2) expansion of grouping (Packet):

As Fig. 2: in the network analog of NS2, mutual elementary cell between grouping (Packet) object, it is made up of a series of packets headers and an optional data space, the structure of packets headers just is initialised when the Simulator Object Creation, each packets headers also goes on record with respect to the side-play amount of the initial address of grouping simultaneously, here the packets headers of NS2 just comprises commom head, IP head, TCP head, RTP head, MA head and trace head, this means no matter whether certain packets headers can be used under default situation, and it all can be initialised.The user can be the packets headers of new protocol definition oneself, also can expand existing packets headers by the mode that increases the territory.Add the method for new packets headers, in C++, define earlier exactly and comprise required domain structure (structure), define the connection that a static class is provided to Otcl again, revise the setup code of some simulations then and specify the byte offsets of new packets headers in grouping.

Associated documents in editor's NS2 source code (as ns-packet.tcl etc.), so that this new head construction loads and initialization when NS2 starts automatically, so the major part of packets headers can be expressed as:

enum?packet_t{

……

PT_MA，

……}；

……

class?p_info{

public：

p_info(){

……

name_[PT_MA]＝″ma″；

……}}；

3) expansion of Node, as Fig. 3:

In the node node of original NS2 structure, data are reported for work and are reached after this node, at first judge it is unicast data newspaper or multi-case data newspaper, and in view of the above datagram are passed to corresponding clean culture module or multicast module.Report owing to increased a kind of special data that comprises mobile agent now, therefore just need to revise original node structure, when the datagram of a mobile agent type is received in judgement, it should be delivered to the middle operation of mobile agent execution environment (MAE) of this node.

4) expansion of Agent

Set up MAE, and on node, load.After mobile agent is moved to the node that has loaded MAE, just can move thereon.In NS2, the functional unit of handling the variety of protocol packet in the node is called " agency " (Agent), therefore, derive from the most basic Agent and can support Agent that mobile agent moves as MAE.

As shown in Figure 3, expansion comprises two parts: at first be the function that strengthens switch_, make it can judge whether the Packet that receives is mobile agent; Next is to increase a MA grader of handling the mobile agent packet.After switch_ judges that a Packet is mobile agent, just it is sent to the MA grader, by the latter mobile agent is sent to attached to the MAE on this node then, thereafter, the Activate function that MAE just can call mobile agent activates it.In addition, can also specify a node whether can load MAE.Mobile agent can only move on the node that has loaded MAE, and in the node that does not load MAE, mobile agent will be handled as the general data newspaper.

The realization of two .MAMRQoS in NS2:

The architecture of NS2 is open, so it allows the researcher for it adds new function, realizes new network topology and new discharge model.NS uses bilingual, C++ and Otcl, the C++ program operation speed is than very fast, it is the forced type language, need carry out strict data type inspection, realize complicated data type easily, realize accurate, complicated algorithm easily, but the time that modification, debug and recompility are spent is longer, so C++ is adapted to the realization of concrete agreement.The Otcl operation is slower, revises but carry out interactive mode easily, does not need compiling, and is not forced type, is difficult for makeing mistakes, and its adaptation is used for doing analog configuration.Realize that at the task choosing different language of doing the analog configuration basis new code adds in the NS2 system, realize emulation the QoS Multicast Routing Algorithm of Ant-like mobile agent.Because what will realize is the QoS mechanism of Ant-like mobile agent, writes the software with Mobile Agent mechanism, adds to then among the NS2, carries out emulation and simulation.

Three. simulation result:

By to Ant, OQMRA and MAMRQoS three's emulation relatively comes the average behavior of assessment algorithm, in emulation experiment, generate by improved NS2 software kit, the node number is 50, postpone end to end by transmission lag and the decision of circuit propagation delay, mainly compared average call completing rate and the corresponding communication expense of 3 kinds of algorithms under the heterogeneous networks loading condition, every is the mean value of 20 simulation results on the curve, each emulation produces 100 connection requests, following rule is obeyed in the generation of request, the source and destination of calling out is to choosing the bandwidth of call request randomly from set of node with uniform probability, duration, maximum end to end permission postpones all to obey evenly to distribute.Prove that by experiment OQMRA not only can improve the transmission quality of network packet effectively, but also can save routing selecting time greatly, finds optimal solution (or near-optimum solution) very soon, OQMRA can also realize global optimization.According to the characteristics of ant mobile agent QoS multicast route, the method for MAMRQoS has been proposed, simulation result shows that MAMRQoS has solved the network equalize problem well, for the QoS multicast routing issue that solves multiple constraint provides a new method of thinking.

Claims (1)

1. the method based on the QoS multicast route of Ant-Like mobile agent realizes mobile agent under network simulator NS2, it is characterized in that:

One, sets up network model: multicast tree T (V _T, E _T) satisfy:

Delay constraint, delay (P (s, m))≤D, Pm ∈ M. (1)

Bandwidth constraint bandwidth (P (s, m)) 〉=B, e ∈ P (s, t) (2)

In the formula: the P delegated path, s represents source node, and m represents destination node, and D represents maximum delay, and B represents minimum broadband;

Two, NS2 is done the expansion of following four aspects:

1) expansion of class: expansion mobile agent MA grader in the address sort device;

2) packet expansion: expansion MA head in the packets headers of NS2;

3) expansion of node node: in the node node of original NS2 structure, increased a kind of special data newspaper that comprises mobile agent;

4) expansion of Agent: set up mobile agent execution environment MAE, and on node, load; Expansion comprises two parts: at first be the function that strengthens switch_, make it can judge whether the Packet that receives is mobile agent; Next is to increase a MA grader of handling the mobile agent packet.

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