Mobile Agents in Telecommunications Networks A Simulative Approach to Load Balancing

Transcription

1 Moble Agets Telecommucatos Networks A Smulatve Approach to Load Balacg Steffe Lpperts Departmet of Computer Scece (4), Uversty of Techology Aache Aache, 52056, Germay Ad Brgt Kreller Corporate Techology Departmet, Semes AG Much, 8730, Germay ABSTRACT Networks today are growg cotuously complex, wth ew kds of servces beg cluded ad heterogeeous etworks terworkg as a whole. Telecommucatos etworks partcular have become truly global etworks, cosstg of a varety of atoal ad regoal etworks, both wred ad wreless. Cosequetly, the maagemet of telecommucatos etworks s becomg a creasgly complex task, as sze ad complexty costtute crtcal requremets that have to be met. Decetralzed approaches to etwork maagemet are curretly beg dscussed, as s has become evdet that cetral solutos caot cope wth scalablty ssues. Moble aget techology partcular s beg examed as a ew dstrbuted system ad etwork paradgm. Oe vtal ssue telecommucatos etworks maagemet s load balacg, as t allows to effcetly use the etwork to capacty ad avod overload stuatos. I ths paper, we wll exame swarmg tellgece of moble agets as a bass for the developmet of a decetralzed load balacg mechasm telecommucatos etworks. Varous strateges for swarmg tellgece wll be evaluated ad compared to covetoal approaches wth a smulatve approach. Keywords: Moble Agets, Smulato, Load Balacg, Telecommucatos Networks, Swarmg Itellgece.. INTRODUCTION Telecommucatos etworks today are volatle commucato etworks whch cosst of heterogeeous, very ofte compatble, mult-vedor evromets. Crcumstaces such as these cause the maagemet of telecommucatos etworks to be complex ad to cota operator-tesve tasks that eed cosderable huma volvemet. Legacy etwork maagemet systems [,2], however, follow a cetralzed approach whch causes a umber of problems. The maagemet formato to be processed threates to excess the capabltes of the huma maagers. Moreover, the maagemet solutos are sestve to the rapdly chagg etwork codtos ad addto caot effcetly cope wth the growg scale of the etworks. I order to avod the formato overload, decetralzed approaches to etwork maagemet are curretly beg examed [3,4], wth moble aget techology [5,6] playg a crucal role may of these approaches [7,8]. Ths paper focuses o a moble aget based approach to load balacg telecommucatos etworks. Load balacg ams at evely dstrbutg the load over a etwork, thus leavg o routers dle ad prevetg overloads for others. If o load balacg mechasms are appled, etwork cogestos ca occur eve f may of the etwork s odes are ot used to capacty at all. Cetralzed approaches to load balacg, whch wll be dscussed more detal secto 4, suffer from the same problems as other cetralzed maagemet solutos. Therefore, ths paper we preset a dstrbuted approach whch s motvated by bologcal pheomea. I ature, several examples ca be observed where a tellget ad effcet behavor of a overall system results from the terworkg of autoomous dvduals obeyg smple rules, e.g. sect swarms, fsh schools, ad brd flocks. Ths behavor s beg examed by Artfcal Lfe [9], a research area whch forms part of the Artfcal Itellgece (AI) work. Artfcal Lfe tres to determe whch way the smple rules ad behavoral patters result a overall system executo. For ths, the autoomous dvdual staces ad the rules drectg ther local teracto ad goal-drected behavor are beg examed. It has bee foud out that there s o behavoral cotrol o a global level, whch s called localty of the system. It s rather a property called emergece whch causes the complex, dyamc, ad structured behavor o system level. Emergece s the crucal property Artfcal Lfe ad deotes the occurrece of a system property drawg from the teracto of dvdual compoets, wthout havg bee specfed explctly or beg drectly deductble [0]. The term self-orgazato ths cotext descrbes the emergece of a mproved system structure, e.g. wth regard to stablty or fault-tolerace. Apart from the autoomy of the compoets, ther localty, ad emergece, there are a umber of addtoal characterstcs of such systems. Sce all of the compoets act autoomously ad locally, they have a hgh degree of parallelsm. Ths parallel dyamsm dffers from the predomatly sequetal mode of executo whch s gve tradtoal computer ad etwork archtectures. Trasferrg results of Artfcal Lfe to computers ad etworks therefore

2 troduces a ew problem solvg approach whch wll be dscussed detal the followg. Aother property of Artfcal Lfe models s called temporal varace of the compoets,.e. these compoets have a predefed lfecycle. They are created ad the rema uchaged, whle able to multply, ad evetually are termated. The latter ca be trggered by the stace tself or by aother compoet. Ths lfecycle s ofte exteded by moblty,.e. the compoets are able to move through the system autoomously. Together wth the gve lfecycle, especally the ablty to multply, the populato of the system thus ca dyamcally adapt to a chagg evromet. I the followg secto, we wll descrbe swarmg tellgece whch deals wth the emergece of group behavor ad show how t tegrates wth Artfcal Lfe. We wll the pot out how moble agets ca be regarded as a challegg techology for swarmg tellgece strateges. Secto three troduces a swarmg tellgece archtecture for load balacg telecommucatos etworks whch s based o moble agets. Secto four descrbes dfferet strateges for the load balacg process whch ca be mplemeted wth moble agets. The developmet of a smulatve tool for the evaluato of these strateges ad the results are preseted secto fve. The fal secto cocludes wth a summary ad a outlook o future work. 2. SWARMING INTELLIGENCE I the frst secto, Artfcal Lfe has bee troduced as a ew problem solvg paradgm for complex dstrbuted systems ad etworks. Research Artfcal Lfe ca be dstgushed two categores. Frst, work s beg executed to aalyze ad mtate bologcal ad socal mechasms. Secod, the applcato ad adaptato of models for lfelke behavor basg o bologcal systems to artfcal systems s amed at. I order to acheve the latter, partcular to apply Artfcal Lfe models to computer ad commucato etworks, moble agets costtute a promsg techology, as ther characterstcs ca be mapped drectly to the prcples outled above. moble aget creato ad cofgurato take both ther code ad status alog ad trasfer themselves to aother host ad cotue executo there, thus fulfllg the moblty property. The ablty to mgrate also eables the meetg cocept where moble agets frst meet at a commo locato ad the teract locally, thus addressg the localty property. Fally, as moble agets act autoomously ad addto are parallel processes, they ca be take as a bass to trasfer Artfcal Lfe models to computer ad commucato etworks. I ths paper, moble agets techology s used for a decetralzed load balacg of telecommucatos etworks. The problem solvg techque appled s a swarmg tellgece method,.e. based o depedet, autoomous agets wth the overall system behavor drawg from the emergece of ther teracto. Fgure 2 shows how swarmg tellgece ca be classfed as part of Artfcal Lfe. Swarmg tellgece solutos offer a umber of advatages f appled dstrbuted system ad etworkg ssues. Frst of all, cotrast to cetralzed approaches, there s o problem wth scalablty, as a swarm of depedet agets costtutes a etrely decetralzed soluto whch ca adopt to the sze of a system by reproducto ad mgrato. I addto, swarmg tellgece provdes hghly adaptve systems, as the agets lfecycle ad ther ablty to mgrate allows to dyamcally adopt to chagg system requremets. Therefore, swarmg tellgece s partcularly sutable for large ad hghly dyamc systems. Moreover, wth agets beg autoomous,.e. able to execute wthout relyg o other agets, the overall system based o depedet agets s robust ad fault tolerat. Whle the crash of a cetral compoet a cetralzed approach wll cause the etre system to fal, the termato of a group of agets ca cause a system to act less effcetly, but t wll ot cause the etre system to halt. Cellular Robotc System Decetralsed Robotc System Sesor-Based Behavour Group Itellgece Emergece of Orgazato/Socety Emergece of Group Behavour Coloy of Socal Isect Socety of Huma Begs Ats Fsh School Swarmg Itellgece Flock mgratg executg suspeded Collectve Itellgece Bees Emergece of Idvduals returg home Reforcemet Learg Cellular Automato L-System Artfcal Neural Network Geetc Algorthms dyg Fgure : The Moble Aget Lfecycle Model As show fgure, moble agets adhere to a lfecycle whch s detcal to the property of temporal varace. Equally mportatly, moble agets are able to mgrate,.e. to Fgure 2: Swarmg Itellgece Artfcal Lfe Last but ot least, cocevg a problem soluto based o dvdual ad self-cotaed compoets results hghly modular ad clearly structured systems, thus mprovg mateace ad updates. Bearg these potetal beefts md, the ext secto explas how moble aget techology ca be deployed for a swarmg tellgece the load balacg process of a telecommucatos etwork.

3 3. A MOBILE AGENT BASED ARCHITECTURE FOR LOAD BALANCING A vtal ssue telecommucatos etworks s the avalablty of les ad servces. Frst of all, t must be esured that the umber of calls whch are blocked or lost are kept to a mmum. At frst sght, t mght therefore be a straghtforward soluto to geerously provde capactes to avod stuatos of hgh load. Ths, however, s ether effcet or ecoomcally feasble. It must rather be amed at utlzg the avalable capactes to a maxmum degree. Load balacg addresses the topc of dstrbutg load over the odes of a etwork. As a cosequece, a hgher umber of calls wll the be allowed to go through ad co-exst. Recet research demostrates the geeral applcablty of moble aget techology for etwork maagemet ad ts potetal beefts [7,8,], especally f the moble agets form a swarmg tellgece [2,3]. Examatos of swarmg tellgece specfc areas of etwork maagemet cover cofgurato maagemet [4] ad fault maagemet [5]. I the followg, we wll focus o swarmg tellgece wth moble agets for load balacg telecommucatos etworks ad preset a decetralzed archtecture whch suts ths purpose. As dscussed later ths paper, t wll serve as a eablg techology for the load balacg strateges. I accordace wth the approach troduced [6], two classes of moble agets are defed by the archtecture depcted fgure 3, load agets ad strategy agets. Load agets operate o the lowest layer of the archtecture. If a load aget s emtted to the etwork, t wll determe the paths offerg the largest free capacty from the curret ode to each of the other odes the etwork ad the modfy the routg tables accordgly, makg use of ts ablty to mgrate to the other odes. The algorthm of Djkstra [7] s appled, ad the moblty of agets allows a straghtforward realzato of ths algorthm. Whle the detals of the algorthm are omtted here, t s mportat to ote that the updates of the routg tables have to be made reverse order,.e. startg from the target ode, order to avod loops. Strategy Maager Compoet Dstrbuted Strategy Maager Strategy Maager Compoet Strategy Maager Compoet The remag capacty of a etre path s set by the coecto elemet wth the mmum free capacty. Hece, the determato of the path offerg the maxmum free capacty requres a examato of all avalable paths ad ther elemets ad the selecto of the path wth the maxmum value. I ths process, both the lks ad the odes of a etwork ca be take to accout, because ether of these ca form a bottleeck for a coecto. Hece, wth gve odes ad lks of varyg capactes, dfferet paths ca be selected accordg to the selecto crtera. A example s gve fgure 4. The umbers dcate the free capacty of the lks ad odes. Takg oly the values of the lks to accout wll result a selecto of path A, whlst regardg the odes or both lks ad odes wll result selecto of path B. The fgure thus also expresses that depedg o the selecto crtera, the path whch s selected eed ot be the shortest coecto, as there s also a drect coecto betwee the two odes avalable. The selecto of loger paths wll result a creased load of the overall etwork. Therefore, load agets ca also be structed to prortze short paths. Deployg moble agets to execute the updates of the routg tables allows to easly modfy the selecto crtera. It s doe smply by emttg the correspodg agets whch wll do the requred modfcatos of the routg tables whle cosderg a gve subset of the crtera. Hece, a chage of the crtera ca eve be doe at rutme by emttg agets wth a modfed set of crtera. Ths s a dcato of the flexblty of the moble aget approach, addto the modularty of the archtecture gve by the fact that the modfcatos of the load agets are etrely trasparet to strategy agets whch operate o top of them. Aalogously, the operato ad modfcato of strategy agets s depedet of the uderlyg load agets Path A Path B Strategy Agets Load Agets Fgure 3: Outle of the Load Balacg Archtecture Fgure 4: Selecto of the Optmal Path Strategy agets are resposble for the populato of load agets,.e. ther creato ad termato, ad for delegatg tasks to them. Sce o cetral stace s gve the moble aget approach for load balacg, strategy agets wll move aroud the etwork radomly ad gather formato about the lks ad odes, such as the curret load ad the umber of

4 calls orgatg from a ode. Comparg the curret values of the load to the mea values of former vsts, the strategy agets ca detect chages of the traffc ad the etwork tself ad the decde o emttg load agets accordgly. What umber of load agets to be created ad whch ode to select for ther emsso, these factors are determed by the strategy appled by the strategy aget. These strateges are preseted detal chapter 4. Accordg to the resposbltes of the strategy agets, they operate two dfferet modes. The frst mode s a purely observg oe, where formato about the evromet s beg collected. If a rregularty or overload stuato has bee detected, the strategy aget wll swtch to the secod mode where t wll emt load agets ad thus start fxg the stuato, f o other strategy aget has already started ths process. Accordg to these two modes, strategy agets wll mutually fluece ther route. A strategy aget wll move to aother ode, f the curret ode s already beg observed by a predefed umber of agets, f aother aget s already workg o that ode, or f there already s a suffcet umber of load agets updatg the routg tables the etwork. Ths two-layered archtecture offers the advatages of load balacg whch were dscussed secto 2, e.g. scalablty ad adaptablty. Drect ter-aget commucato, a mportat research ssue for eablg moble aget deploymet may applcato domas, s a crtcal factor for moble aget solutos. It s curretly beg addressed by stadardzato [8,9] ad research [20,2,22]. Based o swarmg tellgece, the archtecture preseted here s etrely based drect commucato of agets,.e. both load ad strategy agets leave marks for ther peers ad other agets to be foud. Ths avods problems of aget sychrozato ad also equps the archtecture wth addtoal robustess. What s stll eeded, however, s a addtoal layer for the maagemet of the strategy agets, whch wll allow operatos such as motorg, chage of strateges etc. The thrd layer s a Dstrbuted Strategy Maager, depcted fgure 3, whch cossts of dstrbuted Strategy Maagemet Compoets. The Dstrbuted Strategy Maager thus adheres to the de-cetralzed approach ad offers vsualzato ad steerg facltes to the huma maager. For example, f a chage of strategy s to be carred out, the Strategy Maagemet Compoets wll be told to termate all strategy agets followg the expred strategy ad replace them wth ew oes. If a strategy aget has crashed, a ew strategy aget wll be created by a Strategy Maagemet Compoet. Addtoal strategy agets wll be created, f a etwork error s mmet ad error detecto ad recovery s to be stregtheed. Tmestamps ca be deployed to determe falure of agets ad also the curret aget populato of the system. For detals o tmestamp usage, see [6]. A archtecture based o reactve moble agets as preseted ths chapter allows dfferet strateges for load balacg telecommucatos etworks. I the followg chapter, detals of these strateges are dscussed order to expla ther mode of operato, before ther effcecy s aalyzed secto LOAD BALANCING STRATEGIES The edeavor to optmze the usage of etworks ad partcular telecommucatos etworks has lead to tese vestgatos of dstrbutg load over the avalable odes. Accordg to the effort made to balace the load of a etwork, three ma groups of routg strateges ca be dstgushed: statc strateges, dyamc strateges, ad swarmg tellgece strateges wth moble agets. I the begg, oly statc routg was appled. I these approaches, specfc routg tables were geerated before a etwork was take to operato. These routg tables were depedet of tme ad load stuatos. Methods belogg to ths category are for stace FIX (Fxed Routg) ad FAR (Fxed Alterate Routg). I the FIX strategy, all routg tables are set up to cota oly the shortest path to the destato odes. Cosequetly, o load balacg s doe, sce all coectos betwee odes are predetermed. Wth the etwork s load growg, however, t s obvous that these paths soo wll overload ad calls wll be lost, as there s o adaptato to ths stuato. Therefore, the FARx strategy, x alteratve paths to a destato ode are memorzed a ordered lst. If the capacty of the optmal route s low or suffcet, the followup route wll be chose from ths ordered lst of paths. Although ths approach allows to avod overload stuatos through a frst, yet very rgd load balacg, t stll does ot adapt to the actual load of the etwork. I recet years, dyamc strateges have come up whch allow a adaptato of the routg tables at rutme, depedg o the gve etwork load. The best kow strateges of ths category are DAR (Dyamc Alterate Routg) from Brtsh Telecom [23], ADR (Adaptve Dyamc Routg) from Norther Telecom [24,25], ad DNHR (Dyamc No- Herarchcal Routg) from AT&T [26]. All of the dyamc strateges determe a umber of alteratve paths from source odes to destato odes, but cotrast to statc strateges, the curret load of the odes ad lks are take to cosderato whe ths lst of paths s frequetly updated. Ths guaratees that stuatos of hgh load o a gve path, the alteratve path whch meets the curret stuato of the etwork best wll be selected. A ew category of strateges s establshed whe evaluatg the applcablty ad effcecy of moble aget based swarmg solutos for load balacg, whch would provde the beefts descrbed secto 2. I the remader of ths paper, we wll preset fve strateges of ths kd [27] whch are realzed wth the archtecture descrbed secto 3. Ther performace wll be compared to fve strateges represetg the frst two groups, amely statc, mult-path ad alteratve routg, wth a specfcally developed smulato tool. Two statc strateges (amed strategy 0 ad ) have bee examed. They dffer the umber of alteratve paths avalable for coectg source ad destato odes. I strategy 0, the optmal path accordg to the algorthm of Djkstra for coectg each source ode to the destato odes s calculated advace ad wrtte to the routg tables, ad o load balacg s doe at rutme. Strategy, however, selects a predefed umber of low-cost paths from the set of all possble paths. Sce there mght be a huge overall umber of paths, a restrcto of the legth of the paths to be selected ca be troduced va a hop cout. I the smulato preseted secto 5, the load strategy wll be evely dstrbuted over all of these low-cost paths. Three strateges (amed strategy 2, 3, ad 4) represetg the class of dyamc strateges have bee smulated. Strategy 2 s a decetralzed alteratve routg, where all alteratve paths (possbly restrcted by a hop cout) are determed advace. O etwork operato, each of the odes wll exame ts

5 curret load fxed tervals ad wll select the most sutable path from the predefed set, depedg o ths local formato. Strategy 3 s also decetralzed, but does ot operate o a gve set of alteratve paths. It rather calculates the optmal path to destato odes o the fly, usg the Djkstra algorthm. Ths calculato process s trggered parallel o all odes gve tervals. A varato of ths approach s gve wth strategy 4. I order to avod the massve computato requred strategy 3, the process of applyg the Djkstra algorthm s here started o the odes of a etwork a sequetal order, also gve tervals. The strateges based o the swarmg tellgece archtecture preseted above are amed strategy 5 to 9. They operate o routg tables whch are tally set to the optmal paths betwee odes (oly strategy 9 holds a lst of alteratve paths) ad dyamcally ad adaptvely modfy these routg tables durg etwork executo through the load agets. The strateges dffer from each other the appled method to determe the locato for emttg the load agets to the etwork. I strategy 5, the strategy agets select the ode for lauchg a load aget from of a lst cotag the te most recetly vsted odes. From ths lst, the ode s selected where most calls orgate from,.e. the oe wth the hghest source rate. Load agets strategy 6, however, wll be started o a ode ext to the oe whch curretly holds the largest source rate. Ths ams at freeg capacty at the overloaded ode wthout addg the addtoal computato overhead for the route calculato to the ode tself. Smlarly, strategy 7 starts load agets o all eghborg odes of the overloaded ode, order to maxmze the amout of traffc take away from t. Strategy 8 s smlar to strategy 5, but here threshold values are troduced to avod stabltes. These stabltes have emerged wth strategy 5 ad were caused by a cotuous re-routg of the load. Fally, strategy 9 s a modfcato of the alteratve routg gve strategy, as all possble paths from oe ode to aother are computed advace. Load agets here are emtted aalogy to strategy 5, but they operate oly of the predefed set of alteratve paths,.e. f a strategy aget detects a overloaded ode, a load aget wll be emtted to the ode wth the maxmum source rate. It wll the determe the path offerg the largest free capacty from the set of kow paths. Ths holds the advatage that the computato effort s reduced, but t also eglects eve better paths whch are ot cotaed the set. The followg secto presets the aalytcal codtos ad the results of the smulatos for the dvdual strateges ad thus dcates, whch way moble aget based swarmg tellgece ca cotrbute to load balacg of telecommucatos etworks. 5. SIMULATION RESULTS The am of load balacg mechasms s to evely dstrbute load over a etwork, thus leavg o odes dle ad prevetg overload of others. I other words, the varace of the load over all odes wth a etwork s to be mmzed. I order to formally specfy ths property, the load of a etwork has to be examed more detal. Let s (t) be the overall load caused at ode by outgog calls whch termate at ode k,.e. s ( t) = (I) A k k= Aalogously, let r (t) be the overall load of comg calls at ode, amely r ( t) = (II) A k k= Addtoal load at ode results from paths from ode j to ode k that use ths ode. Ths load s gve by u ( t) = j, k= j k A jk (III) Wth (I-III), the etre load L (t) curretly gve at a ode ca therefore be determed as L (t) = s (t) + u (t) + r (t), where s, u, r 0 (IV) Gve the load of the dvdual odes of the etwork, the mmum varace of the loads the etwork ca be expressed wth the followg optmzato fucto: MIN = t 2 k= t = L t) L ( ) t dt = k ( t 2 t = k= k L ( ) ( ) t Lk t dt (V) Bascally, what s descrbed here s a summato of the load of all odes whch s the dvded by the umber of odes the etwork. Ths wll result the mea load the etwork at tme t. Gve ths mea value, the absolute value of each ode s load varyg from the average load s determed. The summato of these values ad ther tegrato gves the varace of the load the etwork. load uts Frot to back: Strategy 5 (swarmg) Strategy 8 (swarmg) Strategy 9 (swarmg) Strategy 4 (dyamc) Strategy 3 (dyamc) tme/hour Strategy 6 (swarmg) Strategy 7 (swarmg) Strategy 2 (dyamc) Strategy 0 (statc) Strategy (statc) Fgure 5: Comparso of the Mea Varace of all Strateges

6 Ths formula has bee take as a bass for realzg a smulatve tool, whch helps to compare the load balacg strateges preseted above. For a gve etwork, the tool frst talzes the routg tables of the odes accordg to the requremets of the curret strategy ad assgs a tal load to the odes. Durg the smulato of the etwork operato, the load of the dvdual odes s frequetly updated,.e. for each ew coecto ad for each termated coecto, the load of the odes volved s modfed accordgly. The umber of calls to be tated ad termated s take from probablty curves deotg the call frequecy at each tme of the day. These curves ca be adapted to sut the dstrbuto of calls over a perod of tme, e.g. to reflect that durg busess hours, a hgher umber of calls s establshed tha at ght. I parallel to the load dstrbuto, the load balacg processes are smulated, wth the moblty of moble agets take to cosderato case of swarmg tellgece strateges. Smulatos have bee made for each of the te strateges. The mea varace of the strateges, whch allows to compare ther overall effectveess, s show fgure 5. It ca be see that the strategy dsplayg the lowest varace ad thus the hghest effectveess s strategy 5, the swarmg tellgece soluto usg the lst of most recetly vsted odes to determe the locato to start the load agets. The hgh adaptablty of ths strategy s depcted more detal fgure 6. The progress of the load dstrbuto over the selected odes very quckly adapts to a creased ad decreased load of the etwork. Ths s a dcato of the load agets takg specfc actos, wth the overall effect beg ot oly a evely dstrbuted load, but also a very stable operato of the etwork, as the mmedate adaptato mmses temporary mbalaces. load uts tme/hour Kote 5 Kote Fgure 6: Load Dstrbuto over the Nodes for Strategy 5 Comparg the swarmg tellgece strateges to the statc ad dyamc oes, fgure 5 also shows that swarmg tellgece offers very effcet solutos. The three most effcet strateges are all swarmg tellgece based. Merely strateges 6 ad 7 perform worse tha some dyamc strateges. Ths dcates that startg load agets o eghborg odes to avod addtoal usage of hghly loaded odes does ot have a suffcet effect o the traffc of the target ode. Fally, t ca be see, that statc strateges are much less successful provdg etwork robustess ad use to capacty. Kote 9 6. CONCLUSION AND OUTLOOK I ths paper, we have evaluated the deploymet of moble agets form of swarmg tellgece for load balacg telecommucatos etworks. Havg troduced swarmg tellgece characterstcs ad beefts, we have preseted a archtecture deployg layers of moble agets whch serves a robust, flexble, scalable, ad adaptve load balacg. The effcecy of strateges based o ths archtecture has bee show a smulatve approach, usg a specfcally developed tool. For ths tool, we have made a aalytcal model of the load dstrbuto a etwork, whch resulted the defto of a formula deotg the varace of the load telecommucatos etworks. As a ma result, t ca be stated that deploymet of autoomous moble agets, whch s beg dscussed for dfferet applcato areas, especally e-commerce, user maagemet, ad etwork maagemet, has prove to offer beefts for etwork maagemet, specfcally load balacg. Future work cocerg load balacg wll focus o equppg the agets wth oe addtoal characterstc, amely the ablty to lear. Ths wll allow the defto of actve agets, rather tha the purely reactve oes deployed here. Agets wll the be capable to uderstad recurrg traffc patters ad to take precautoary actos. For example, they ca be able to foresee stuatos of hgh load ad act e.g. by adjustg the umber of load agets advace. 7. ACKNOWLEDGMENTS Ths work was partally fuded by the Germa Research Coucl (DFG) uder SFB IMPROVE ad GRK 85/ REFERENCES [] Rama, L.: OSI System ad Network Maagemet. I: IEEE Commucatos: Maagemet of Heterogeeous Networks, vol.36, o.3, March 998 [2] Stallgs, W.: SNMP ad SNMPv2: The Ifrastructure for Network Maagemet. I: IEEE Commucatos: Maagemet of Heterogeeous Networks, vol.36, o.3, March 998 [3] Goldszmdt, G.; Yem, Y.: Delegated Agets for Network Maagemet. I: IEEE Commucatos: Maagemet of Heterogeeous Networks, Vol.36, No.3, March 998 [4] Pavo, J.; Tomas, J.: CORBA for Network ad Servce Maagemet the TINA Framework. I: IEEE Commucatos: Maagemet of Heterogeeous Networks, Vol.36, No.3, March 998 [5] Harrso, C.; Chess, D.; Kershebaum, A.: Moble Agets: Are they a good dea? Techcal Report RC 9887, IBM Res., March 995 [6] Pham, A.; Karmouch, A.: Moble Software Agets: A Overvew. I: IEEE Commucatos Magaze, July 998 [7] Bald, M.; Ga, S.; Pcco, G.: Explotg Code Moblty Decetralsed ad Flexble Network Maagemet. I: Proceedgs of Frst Iteratoal Workshop Moble Agets '97, Berl, Germay, Aprl 997

7 [8] Beszczad, A.; Pagurek, B.; Whte, T.: Moble Agets for Network Maagemet. I: IEEE Commucatos Surveys, September 998 [9] Lagto, C.: Artfcal Lfe. Proceedgs of a Iterdscplary Workshop o the Sythess ad Smulato of Lvg Thgs, Los Alamos, New Mexco, 987 [0] Forrest, St.: Emerget Computato: Self-Orgasg, Collectve ad Co-Operatve Pheomea Natural ad Artfcal Computg Networks. I: Emerget Computato. MIT Press, 99 [] Saha, A.; Mor, C.: Eablg a Moble Network Maager (MNM) Through Moble Agets. I: Proceedgs of Secod Iteratoal Workshop Moble Agets '98, Stuttgart, Germay, 998 [2] Whte, T.; Pagurek, B.: Towards Mult-Swarm Problem Solvg Networks. I: Proceedgs of the 3rd Iteratoal Coferece o Mult-Aget Systems (ICMAS '98), July, 998 [3] Whte, T.; Pagurek, B; Oppacher, F.: ASGA: Improvg the At System by Itegrato wth Geetc Algorthms. I: Proceedgs of the 3rd Coferece o Geetc Programmg (GP/SGA'98), July 998 [4] Pagurek, B.; L, Y.; Beszczad, A. et al.: Network Cofgurato Maagemet Heterogeeous ATM Evromets. I: Proceedgs of the 3rd Iteratoal Workshop o Agets Telecommucatos Applcatos IATA'98, Aget-World'98, Pars, Frace, July 998 [5] Whte, T.; Beszczad, A.; Pagurek, B.: Dstrbuted Fault Locato Networks Usg Moble Agets. I: Proceedgs of the 3rd Iteratoal Workshop o Agets Telecommucatos Applcatos IATA'98, AgetWorld'98, Pars, Frace, July 998 [6] Appleby, S.; Steward, S.: Moble Software Agets for Cotrol Telecommucato Networks. I: BT Techology Joural, Aprl 994 [7] Djkstra, E.W.: A Note o Two Problems Coecto wth Graphs. I: Numerc Mathematcs, p , 959 [8] Foudato for Itellget Physcal Agets: Aget Commucato Laguage. Geeva, Swtzerlad, October 997 [9] GMD Fokus: Moble Aget System Iteroperablty Facltes Specfcato. Jot Submsso, November 997 [20] Bauma, J.; Hohl, F.; Radoukls, N. et al.: Commucato Cocepts for Moble Aget Systems. I: Proceedgs of Frst Iteratoal Workshop Moble Agets '97, Berl, Germay, Aprl 997 [2] Dömel, P.; Lgau, A.; Drobk, O.: Moble Aget Iteracto Heterogeeous Evromets. I: Proceedgs of Frst Iteratoal Workshop Moble Agets '97, Berl, Germay, Aprl 997 [22] Lpperts, S.: CORBA for Iter-Aget Commucato of Maagemet Iformato. I: 5th Iteratoal Workshop o Moble Multmeda Com-mu--ca-to, Berl, Germay, October 998 [23] Stacey, R.; Soghurst, D.: Dyamc Alteratve Routg the Brtsh Telecom Trk Network. I: Iteratoal Swtchg Symposum ISS87, Phoex, USA, 987 [24] Chemul, P.; Gauther, P.: Adaptve Traffc Routg Telephoe Networks. I: L Echo de Recherches, Eglsh Issue, 990 [25] Reger, J.; Camero, W.: State-Depedet Dyamc Traffc Maagemet for Telephoe Networks. I: IEEE Commucatos Magaze, October 990 [26] Ash, G.; Cardwell, R.; Murray, R.: Desg ad Optmsato of Networks wth Dyamc Routg. I: Bell System Techcal Joural, vol.60, 98 [27] Kreller, B.: Moble Agets for the Effcet Load Balacg Maagemet Telecommucato Networks. Otto-v.-Guercke-Uverstät Magdeburg, 996