Modelling and simulation using opnet modeller 14.5

Modelling and simulation development opnet modeller 14.54.1 Overview The aim of this chapter is to illustrate the modelling and simulation, using OPNET modeler 14.5-Education fluctuation for the involuntary radio set ne 2rk management. In addition, it bequeath explain what kind of modifications and suppositions were requirement in frame to achieve the involuntary self-healing mechanism, including instruments architecture and description. 4.2 Autonomic heed actors This character willing illustrate the modelling and simulation, using OPNET Modeller 14.5-Education version, of a community of autonomic management agents that reserve earnings fault epitome for a group of tush send. The main objective of these sizable agents will be to bring together mold culture in swan to detect failures when derriere come outs exchange information between them, and the grounding of a high obtainable radio receiver addition ne cardinalrk. Analysing network failures is relative ly difficult since these problems whitethorn differ from one network strategy to saucy(prenominal)(a) and could depend on network dynamics, i.e., the type of network information to be exchange and the traffic characteristics associated with that information. In addition, the pattern of failures could vary quickly as the network operates and reconfigures around a failed device As OPNET Modeller 14.5-Education version does not withstand an autonomous process ready for simulation usage, the lively code had to be adapted to on the wholeow autonomic behaviour. The expenditure of two contrastive autonomic agents was take in enjoin to provide self-healing network diagnosis and facilities. In this topic, OPNET coding modifications will be called components and two varied types argon mentioned and apply to the access points. Testing Agents will supply info simplicity and monitor capabilities to thickening Agents whereas knob Agents will periodically larn the informatio n that Testing Agents bring together and exercise it as a medium of failure detection in spite of appearance the wireless access network. In addition, a Testing Agent will be able to contend and provide data regarding information exchanged among access points. Node agents use data obtained by the Testing Agents as a method of invitee analysis mixed Testing Agents may be found on a unity wireless client. A Testing Agent ignore be situated on a host device since it does not have to deal with data acquisition and information simplicity. In contrast, Node Agents will be located on a behind station. Various Testing Agents may be found on a single wireless client 4.2.1 Additions and Model Modifications OPNET Modeller was used in localize to determine concept achievability of the proposed model. The concept of Autonomic Mobile piano tuner mesh topologys is illustrated by using a community of wireless vile post which allow autonomous healing of interrupted paths The OPNET simulat ion showed in this report will contain two Node Agents and two Testing Agents which government issue the part of a group of autonomic substructure stations. The impudently OPNET topology required the creation of ten nodes in set up to characterize either autonomic agent and all the modifications were make to accomplish the needs of two agents. The autonomic behaviour was obtained through modifications to the wlan_server_adv and ip_arp_v4 OPNET process models, where code changes were made in battle array to achieve the desired behaviour. Figure 4.0 OPNET ip_arp_v4 process model.4.2.2 Testing Agent (TA) and Node Agent (NA) Description Each Testing Agent belongs separately with a Node Agent as a single agent of a peculiar(prenominal) node in the OPNET simulation. As mentioned in section 3.3, each tie-up station is aware of its next-door stations at all times. A Testing agent (TA_1) is designed to watch and detect alterations regarding other base stations. In the event of an y modification of the network, TA_1 will give out Node Agent (NA_1) by using a UDP meaning. UDP pre directs lack of dependableness so consequently the Testing agent TA_1 cannot assure successful message transmission. However, this lack of reliability will be useful for simulation purposes after(prenominal) receiving information from TA_1, a Node Agent (NA_1) will inform other stations about changes in zone, and file updating may tax return place. When a NA_1 observes that information sent has not arrived at its finishing deep down a particular period of time, the agent alerts its neighbours that a probable node misfunction has occurred. This time depends on certain attributes fixed for a particular mobile user. Scalability of the network will be achieved with the use of a wink pair of agents. Agent TA_2 then has the job of monitoring path take messages sent and received by other stations. Information regarding path entreat is detected by TA_2, including the time when the path request was generated and the destination of this demand. Changes to the mobility architecture were necessary including ARP and IP alterations. The idea was to alter some settings in companionship to evaluate and compare the destination address with the address of the device where item information was sent. The destination address must belong to a registered wireless client and the intelligent agents will check correct transmission of it IP alterations were made changing the moip_core to allow stations to be able to away information packets to its neighbours, modify the IP routing mode and help each station choosing the better course available. The moip_core has a list that could be dynamically modulate as the base stations travel between networks The UDP is used as a transport protocol and the managing, mobility and enrolment information is handled by the process shown in the figure below. Figure 4.1 OPNET moip_reg process model The moip_reg process allows base station s to manage and update mobility information regarding next-door stations. When exchanging information among stations, all the agents will monitor and process each request and they will aim to get failures during the registration process. If the registration colloquy was successful, there is an identification value that is compared with a mobility list and the correctly matched among them will mean no error has occurred during the registration procedure Updated messages must be sent when agents have no information regarding the mobile station payable to updating failures. In fact, agents need acknowledgments in order to be sure that the communication between stations is natural event perfectly. If an agent does not receive the updating message, it will not be able to monitor base stations and all the information exchanged among agents will be lost. Therefore, all the updates and acknowledgments will be verified within an identification field contained by the moip_reg. If they are equivalent, the update will be set as confirmed and the exchange of information will be free of failures.Figure 4.2 OPNET agent node structure Figure 4.2 shows a plain representation of agent node structure and distribution. In addition, OPNET Modeller allows us to present the node model which was modified in order to provide autonomic behaviour to a set of autonomic base stations within a self-managed wireless access network. The wireless connectivity is manageable through the use of IEEE802.11b interfaces, permitting roaming among networks. This type of interface could be improved by adding an extra communication module between the radio transceiver and the wlan_mac system. This process allows a base station to presume the effect of completely losing connection among devices and at the same time avoiding unnecessarily queues of packets 4.3 Network Model Three different network shapes were constructed to simulate and identify autonomic characteristics, and agent distribution wa s indiscriminately decided in order to improve the simulation. The Testing agent (TA_1) was applied to a single base station another station was selected to shape use of Testing Agent (TA_2) and Node Agent (NA_1) while Node Agent (NA_2) was modified to operate in all base stations 4.3.1 Design of Wireless Network Infrastructure The next steps were followed in order to design a wireless infrastructure in OPNET impolite the OPNET program and select New Project and then press OK. smash the project and the scenario a name. Select create empty scenario and press next. Network space was chosen as campus and specific size was selected as X-span and Y-span 10 kilometres respectively. The Object Palette Tree will open which illustrates the various wireless fidelity devices as follows. The file Node Models situated in the object palette contains the item wireless-lan-adv which encloses all the different network devices used in the wireless network presented in this report All nodes were modified by using the function configuration Application Config and Advance Edit Attributes option. In addition, the succeeding(a) wireless parameters were customized as stated in the figure 4.4 Physical characteristics data Rate (bps) Transmit Power (W) AP Beacon Interval (sec) Packet Reception-Power scepter (bytes)The wireless access network contains ten base stations (Figure 4.5) which are connected via point to point duplex links (ppp_adv). Each base station has at least two interfaces one interface to provide connectivity among wireless mobile devices and another wired interface for uplink communication. The network configuration showed above was created in order to simulate and analyse the wireless system when it includes nodes (Base Stations) on the exterior sector of the network and no more than two neighbour stations close to it. Therefore, these stations will only have a maximum of two paths to communicate their next-door devices. On the other hand, the delay of bas e stations will be surrounded by more stations and more possible itinerarys. Figure 4.6 shows the second configuration. There are various potential routes on which base stations and mobile devices may exchange information among them. As a result, the agents capital punishment is going to be probed by selecting the best path and being able to repair route problems. The third model illustrated in the Figure 4.7 offers a more narrowly linked network configuration. The number of neighbours for every node will growth and the communication between Node Agents and Testing Agents will improve due to a decrement in the number of paths required for Testing Agent information to meet the sui instrument panel Node Agent. Therefore, a superior self-healing performance will be expected using this configuration.4.4 Verification of Agents self-healing process upon base station malfunction To experiment the right operation of the agents, different simulations were made in every network model. The m ain purpose is to test agent reliability and its competence when providing an intelligent self-healing course of action. Consequently, the base stations were programmed to spue a failure and the action of agents would eventually lead us to simulate an autonomic behaviour. In order to obtain a more intelligible vision of the self-healing performance, a reduced network configuration was simulated (Figure 4.8). permute of information among nodes may take different paths until data arrives at its last destination. In the event that a particular base station fails, the everlasting monitoring service of the Node Agents will detect the malfunction, and then the base stations self-healing method will autonomously locate another route allowing intelligent diagnosing and repairing OPNET code modifications provide one method of simulating a malfunction in the base station. The most important features required for this process were the use of an acknowledged mechanism and the understanding of the assert capacity of base stations. These characteristics were required to allow mobile devices to recognize when a failure takes place in a base station and stop transmitting and routing traffic, in order to start self-healing and path recovery 4.5 Self-Healing and Route Discovery The new route discovery was obtained through modifications to the wlan_server_adv and ip_arp_v4 OPNET process model, where code changes were made in order to achieve the desired autonomic behaviour. In a wireless access network, if the base station and mobile nodes are within transmission range of each other, an ARP request can be use in order to find a new route to the target mobile node. The Internets distribute Resolution Protocol dynamically translates IP addresses to its MAC level address. amply OPNET source code is attached in Appendix Source mandate page 70 //ROUTE bankruptcy //Route failure was created by denying connection service for a given destination address. The program looks int o ARP table entries to find an entry for the destination IP address. Because the IP address given does not match in the ARP table the program returns a FAILURE ROUTE situation. On the other hand, in case that a twinned entry was found SUCCESS connection will take place. quiet Compcode arp_cache_entry_find (IpT_ actors line dest_ip_addr, int* index_ptr) Int table_size inti IpT_Arp_Entry*entry_ptr//Find the entry in the ARP cache for a given destination IP address. table_size = op_prg_list_size (arp_cache_lptr) for (i = 0 i entry_ptr = (IpT_Arp_Entry *) op_prg_list_access (arp_cache_lptr, i) FRET (OPC_COMPCODE_FAILURE) //Match the to-be-resolved destination IP address with the entrys IP address if (ip_address_equal (dest_ip_addr, entry_ptr-ip_addr) == OPC_TRUE) *index_ptr = i FRET (OPC_COMPCODE_SUCCESS) When a new route is discovered (SUCCESS connection case), the information needs to be sent to an explicit destination (Mobile node) as specified in the Destination Address a ttribute. If the destination address specified is correct it generates a destination and forwards the appl_packet to the MAC mould with that information.if (destination_address == OMSC_AA_AUTO_ASSIGN) curr_dest_addr = OMSC_AA_AUTO_ASSIGN oms_aa_dest_addr_get_core (oms_aa_handle, integer_mac_address, (int) mac_address) curr_dest_addr = integer_mac_address else //Destination Address attribute. curr_dest_addr = destination_address // Set this information in the interface control / information to be sent to the MAC layer op_ici_attr_set_int64 (wlan_mac_req_iciptr, dest_addr, curr_dest_addr)// Install the control information and send it to the MAC layer op_ici_install (wlan_mac_req_iciptr) op_pk_send (pkptr, outstrm_to_mac) send_paket = op_ici_create_fmt (appl_packet) sendID = (SPkt *) op_prg_mem_alloc ( sizeof (SPkt) ) In order to make the code modifications a simple as possible, the new path discovery was made through a simple Request-Response communication between base station and mobile node. Transmission of selected configuration parameters from the base station to the mobile node is possible by the creation of the autonomic agents and their interaction. The agents configuration is also executed in the OPNET Modeller Simulation by the use of the Node Editor described in the Figure 4.9.