Mobile Intelligent Agent Technology for QoS Provisioning and Network Management

Transcription

1 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) Moble Intellgent Agent Technology for QoS Provsonng and Network Management ANGELOS MICHALAS 1, MALAMATI LOUTA 2, DIMITRIOS ZISOPOULOS 2, GEORGIA CHARITOUDI 2, GEORGIOS KOUZAS 1 1 School of Electrcal and Computer Engneerng Natonal Techncal Unversty of Athens 9 Heroon Polytechneou, Zografou, Athens, GREECE 2 Department of Busness Admnstraton Technologcal Educatonal Insttute of Western Macedona Kola, Kozan, GREECE Abstract: - The DffServ archtecture provdes a scalable mechansm for QoS ntroducton n a TCP/IP network. DffServ model s based on the aggregaton of traffc flows at an ngress (or egress) pont of a network and the IP packet markng for dfferent prorty flows, accordng to several classfcaton crtera. Two approaches exst n the DffServ archtecture: the Absolute and the Relatve. In Absolute DffServ, an admsson control scheme s used to provde QoS guarantees as absolute bounds of specfc QoS parameters. The Relatve DffServ model provdes QoS guarantees per servce class expressed wth reference to guarantees gven to other classes defned. Our study presents a QoS Provsonng & Network Management System. Ths system s based on an extenson of the network management archtecture followed and mplemented wthn the scope of the European IST Project MANTRIP. MANTRIP network management system supports qualty of servce confguraton and montorng n IP networks. Our extenson provdes QoS Dfferentaton (Absolute and Relatve) n IP DffServ based Networks. The proposed system has been appled and performed well on a real network testbed. Key-Words: - Qualty of Servce, Dfferentated Servces, Absolute and Proportonal Relatve Dfferentaton, Intellgent Moble Agents. 1 Introducton The research communty has concentrated on two dfferent technques to provde QoS dfferentaton to customers of packet swtched networks. Frst, the Integrated Servces (IntServ) [1] and, second, the Dfferentated Servces (DffServ) [2] approach. The major dfference between IntServ and DffServ archtecture s the granularty of servce dfferentaton. The IntServ concept les on resource reservaton noton per applcaton flow, whle n DffServ model, IP traffc s classfed nto fnte, predefned servce classes (on the bass of demand requrements and characterstcs) that receve dfferent routng treatment. DffServ provdes qualty assurances at traffc aggregate level and not at applcaton flow level. Ths way, DffServ acheves scalablty and manageablty, whle on the other hand, IntServ approach faces potental bottleneck problems, snce all routers must mantan nformaton per flow state. There exst two drectons n the DffServ archtecture: the Absolute and the Relatve. In Absolute DffServ [3], an admsson control scheme [4] s used to provde QoS guarantees as absolute bounds of specfc parameters such as bandwdth, packet delay, packet loss rate, or packet delay varaton (jtter). The Relatve DffServ model [5] supports QoS guarantees per servce class wth reference to guarantees gven to other classes. The only assurance comng from the network s that hgh prorty classes receve better (or at least not worse) servce treatment than lower prorty classes. In the context of ths paper, Absolute and Relatve Dffserv Provsonng and Management are acheved through a dstrbuted QoS System. Ths system s based on an extenson of the network management archtecture followed and mplemented wthn the scope of the European IST (Informaton Socety Technology) Project MANTRIP (MANagement, Testng and Reconfguraton of IP based networks

2 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) usng Moble Software Agents) [6]. MANTRIP network management system supports qualty of servce confguraton and montorng n IP networks. Our extenson provdes QoS Dfferentaton (Absolute and Relatve) n IP DffServ based Networks. The mplementaton of the QoS Provsonng & Management system s based on Intellgent Moble Agent Technology (MAT), whch has been consdered as a paradgm that can help servce desgners handle the potentally ncreased functonal complexty nvolved n servce creaton and deployment [7][8]. The man objectve of our system s to provde and manage Qualty of Servce n IP DffServ based Networks [9], wth Moble Agents (MAs) mplementng specfed Applcaton Interfaces (APIs) for Absolute and Relatve Dfferentaton. MAT has already been used for the mplementaton of network, resource and telecommuncaton management servces [10][11][12]. Adopton of MAs as our basc archtectural desgn and mplementaton technology allowed for decentralzaton of the QoS confguraton and montorng tasks. Addtonally, MAT promoted good software desgn, added flexblty, manageablty and scalablty wth a relatvely easy mplementaton of such a complcated system. Furthermore, MAs allowed for the mplementaton of varous Absolute and Relatve Dffserv approaches wthout ntroducng any modfcatons to the man system archtecture. The rest of the paper s organzed as follows. In Secton 2, the Absolute and Relatve Dffserv schemes are brefly revsted. Secton 3, as a frst step, provdes the hgh level archtectural descrpton of the proposed QoS Provsonng and Management System and, as a second step, elaborates on ts functonal procedures. Fnally, concludng remarks are made and ssues for future study are provded. 2 DffServ Archtectural Schemes The man strength of DffServ model s qualty assurance provson at traffc aggregate level, thus allowng for IP traffc classfcaton nto a fnte number of servce classes that receve dfferent routng treatment. Specfcally, routers at the network edges classfy packets nto predefned servce classes based on demand requrements and characterstcs of the assocated applcaton. Core routers forward each packet accordng to a class based schedulng polcy. Ths way, the model provdes servce dfferentaton on each node for large aggregates of network traffc. In Absolute DffServ archtecture, an admsson control scheme s used to provde QoS guarantees as absolute bounds of specfc parameters such as bandwdth, packet transfer delay, packet loss rate, or packet delay varaton (jtter). A connecton request s rejected f suffcent resources are not avalable n the network, so as to provde the desrable assurances. In case of acceptance, the approprate resources are reserved, whle montorng procedures assure end to end performance of the specfc connecton. There are two basc approaches to admsson control [13]. The frst, whch s called Parameter-based approach, computes the amount of network resources requred to support a set of flows, gven a pror flow characterstcs. A key dffculty encountered n most parameter based approaches s ther requrement for reservng resources and mantanng state nformaton per traffc flow on each network node (e.g., traffc parameters, QoS class). The second, measurement-based approach, reles on measurement of actual traffc load n order to make admsson decsons. Consderng measurement-based admsson control technques based on probng, the traffc source or the ngress router probes the network by sendng probe packets at the data rate t would lke to reserve and recordng the resultng level of packet delay or losses. The flow s accepted only f packet loss or delay s below a predefned threshold value. In Relatve Dffserv archtecture, the QoS parameter values of a specfc connecton depend on the network load, snce no admsson control or resource reservaton mechansm exsts. Proposals for Relatve DffServ QoS defne servce dfferentaton qualtatvely [14][15], n terms that hgher classes receve lower delays and losses from lower classes. Recent research studes proposed a qualtatve relatve dfferentaton scheme, named Proportonal DffServ [5][16], whch controls the ratos of delays or loss rates of successve prorty classes n order to be constant. Accordng to ths scheme, gven two consecutve prorty classes, t can be guaranteed that the packet delays or the loss rate for the hgher prorty class can be a specfed porton of the packet delays or the loss rate of the lower prorty class. Consderng the Proportonal Delay Dfferentaton (PDD) model [16], the ratos of packet delays of successve prorty classes are equal to the rato of ther correspondng Delay Dfferentaton Parameters (DDPs) { δ, = 1,... N}. Thus, assumng that we have N classes of servce and the average queueng delay of class- packets s d, the rato of average delays between two servce classes, j s fxed to the rato of ther correspondng DDPs:

3 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) d d j δ = 1, δ j j N (1) In most research efforts carred out, proportonal delay dfferentaton s acheved by employng Prorty Based or Lnk Sharng Schedulers [17][18]. 3 QoS Management System 3.1 Hgh Level Archtecture The QoS Provsonng and Network Management Archtecture s organzed n four dfferent layers. The Applcaton Layer comprses the logc for performng the QoS provsonng and management tasks. Addtonally, t ncludes the Graphcal User Interfaces (GUI) developed n order to provde to the users access to the system n a qute frendly manner. The Servce Layer contans the servces that support the executon of the applcaton. The Adaptaton Layer s responsble for hdng the protocol detals from the Servce Layer and ncludes the network adapters and wrappers. The Network Layer ncludes the network resources. All network nodes support IP DffServ, whch s mplemented by a Class Based Queue (CBQ) scheduler [18] on each network node nterface. The QoS Provsonng and Network Management Archtecture ncludes the followng components and subsystems: The QoS Provsonng & Management Applcaton offers a GUI to both network admnstrators and users. The user s authorzed for requestng a un or b-drectonal connecton reservaton across two Servce Access Ponts (SAPs) by choosng a certan QoS class of servce and gvng certan value for the bandwdth requred, less than or equal to the maxmum bandwdth avalable for the specfc class of servce. The QoS Connectvty Provsonng & Management Subsystem offer layer generc IP connectvty management capabltes to the QoS applcaton. The Connectvty Provsonng & Management subsystem mplements the Connectvty Agents software module as moble agents that are sent as close as possble to the routers to perform the requested connectvty tasks. The Montorng Management Subsystem offers to both users and the admnstrator the capablty to montor the QoS parameters of the confgured connectons. The Montorng Management subsystem explots Actve and Passve montorng technques [19] for obtanng delay/jtter and bandwdth utlsaton/loss statstcs, respectvely. Ths subsystem mplements the Montorng Agents software module as moble agents that are sent as close as possble to the routers to perform montorng tasks. The (Re)Confguraton Provsonng & Management Subsystem allows the admnstrator to (re)confgure certan QoS parameters of the network elements. On one hand, t caters for the ntal confguraton of the routers (.e., defne parameters for the servce classes of the DffServ model) and on the other hand, f a certan path flow s volatng the thresholds defned by the QoS class of servce parameters, the admnstrator may trace the route of the specfc connecton (f statc routng s beng used), get the queue load of the routers nvolved and reconfgure them n order to mprove the end-to-end QoS. In essence, ths subsystem allows for the confguraton and reconfguraton of the queue sze per class of servce and of the maxmum bandwdth allocated to each servce class. Ths subsystem mplements the (Re)Confguraton Agents software module as moble agents that are sent as close as possble to the routers to perform (re)confguraton tasks. At ths pont t should be noted that the (Re)confguraton Agents may estmate new bandwdth values takng nto account both the queue load per class, and the requred delay spacng among classes defned by the user. Informaton concernng the network topology, the QoS class of servce templates, the routers and ther confguraton parameter values (bandwdth gven to each servce class, queue sze), the users and ther accepted connectons confguratons (e.g., bandwdth) are stored n the system database. Concernng the mplementaton ssues of the QoS Provsonng and Network Management System, all the subsystems have been mplemented n Java n the context of [8]. Fnally, Connectvty Agents, Montorng Agents and (Re)Confguraton Agents have been mplemented as ntellgent moble agents based on the use of Voyager platform [20]. 3.2 QoS Management System Functonalty QoS Provsonng & Management System caters for the ntal confguraton of the network routers (.e., defnton of the QoS parameters of the DffServ servce classes on the bass of past experence/ hstorcal data) by means of the Confguraton Agents sent from the (Re)Confguraton Provsonng & Management subsystem (mplemented on the management staton) as close as possble to the routers n order to perform ther msson. Consderng a connecton reservaton request for Absolute QoS across two SAPs ssued by the user,

4 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) as a frst step, the QoS Provsonng & Management System performs Call Admsson Control. In case creaton of the connecton s authorzed (.e., there are avalable network resources to serve the requested connecton), the system proceeds wth the establshment of the connecton by confgurng the routers assocated wth the specfc path across the two SAPs. For parameter based approach, connecton admsson s based on the avalable bandwdth per lnk across the path from the source SAP to the destnaton SAP. Measurement based admsson control s mplemented usng the Montorng Management subsystem. To be more specfc, as a frst step, the connecton s created, but s not set nto actve mode. As a second step, the Montorng Management subsystem performs actve and passve montorng for ths connecton and accordng to the packet delay or packet loss experenced the connecton s accepted or otherwse rejected. In case the user requests Relatve QoS (e.g., Proportonal Delay Dfferentaton), the system does not perform admsson control. Instead, Reconfguraton Agents are ntated by the admnstrator and sent on each router s outgong network nterface to estmate and allocate new bandwdth values (servce rates) to servce classes of the CBQ schedulers. Takng nto account the fact that n Absolute DffServ most admsson control schemes [21][22] consder average traffc arrval rate, n conjuncton wth the non statc n general source s behavour, congeston s lkely to emerge partcularly on the core network routers. Consderng the case of hgher servce class overloadng (e.g., such may be the case of smultaneous actvaton of many applcatons of a hgh rated servce class), worse packet forwardng may emerge wth respect to the lower servce classes. In such a case, servce rate reconfguraton of routers output lnk s requred n order to provde the best QoS possble per flow. Consequently, assumng that users and applcatons cannot get the requested absolute servce level assurance, such as an end-to-end delay bound or throughput due to network resources nsuffcency, a consstent servce dfferentaton on output lnks of core routers should be provded, so that most of the QoS requred levels are satsfed. Smlarly, Relatve DffServ could be acheved by reconfgurng the servce rate of each class accordng to ts packet arrval rate and buffer occupancy. Authors prevous work on these ssues nclude [23][24][25][26]. In our system, the Reconfguraton Provsonng & Management subsystem s responsble for preservng dynamcally the specfed end-to-end Absolute Delay Constrants (ADCs) or/and Relatve Delay Constrants (RDCs) for establshed connectons. Specfcally, a Reconfguraton Agent created by the Reconfguraton Management subsystem s sent to the Adaptaton Layer of each core router of the Dffserv network. The Reconfguraton Agent retreves regularly the number of packet arrvals a (t), the number of packet departures dp (t), and the number of packet drops dr (t) per class of servce. Thereafter, t fnds the current router queue load: q ( t) = a ( t) dp ( t) dr ( t) and estmates the current delay per class of servce: q ( t) d ( t) =, r ( t) where r (t) s the current servce rate of class-. The results are sent to the Reconfguraton Manager, whch, n accordance to the d (t) values, can predct f an absolute or relatve delay constrant volaton on a specfc connecton exsts. In case of an ADC or RDC volaton, t ssues a reconfguraton request to the Reconfguraton Agents n order to dynamcally reconfgure the servce rates per class of servce on each node nvolved n the connecton. Do after perod U Estmate class delays d (t) ADCs volated No RDCs volated Yes Yes Ignore RDCs Fnd r (t) subject to ADCs Fnd r (t) subject to RDCs Relax RDCs of ADC volated classes Fnd r (t) of ADC volated classes Fnd r (t) subject to RDCs No Done Fgure 1. Servce Rate Computaton Algorthm for absolute and relatve delay dfferentaton provson. The servce rate computaton algorthm appled for absolute and relatve delay dfferentaton s depcted n Fgure 1. Specfcally, n case of an ADC volaton, the algorthm relaxes RDCs and tres to satsfy only the strct ADCs. To ths respect, as a frst step, the avalable resources of servce classes are utlzed n order to succeed n satsfyng the ADCs of all servce classes. The process s terated untl an ADC volaton does not exst and all avalable resources have been redstrbuted. If after the completon of the reassgnment process there are stll classes that volate ther ADCs, the strct ADCs of the lower prorty servce classes are relaxed n favour of the hgher order classes. Thus, the servce rates of the hgher order classes may stll be ncreased by reducng accordngly the rates of the

5 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) lower prorty classes, untl a mnmum predefned servce rate has been reached. It should be noted that, n such a case, the ADCs of the lower servce classes are volated. In case of an RDC volaton, the servce rates per class of servce are re-estmated n accordance to (1). In the new soluton volates an ADC defned for a servce class, ts correspondng RDC s relaxed. The proposed system supports the reconfguraton task ether on a statc or on a dynamc base. In the statc case, the servce rates are adjusted to the CBQ scheduler once, when a reconfguraton request s ssued by the network admnstrator. In the dynamc case, the system acheves the requred absolute and/or relatve dfferentaton provson through the dynamc adaptaton of the servce rates of the router s output lnk per servce class. The system montors the network load and QoS condtons and adjusts the servce rates n case the predefned thresholds are about to be exceeded, whle n parallel, a notfcaton s sent to the network operator. Thus, acton s taken before potental servce level agreements (SLAs) are breached and the customer s experence s adversely affected. 4 Concluson In the context of ths paper, Absolute and Relatve Dffserv provsonng and management n packet swtched networks are acheved through a dstrbuted QoS System. The mplementaton of the proposed QoS provsonng & management system s based on Intellgent Moble Agent Technology (MAT), whch added flexblty, scalablty, manageablty to our system, whle at the same tme allowed for a relatvely easy mplementaton supportng even varous confguratons wthout ntroducng major modfcatons to the man archtectural desgn. As a frst step, after brefly revstng the Absolute and Relatve DffServ models, the hgh level archtecture of the QoS Provsonng and Management System was presented. Thereafter, the authors elaborated on ts functonal procedures. Specfcally, ths paper presented the procedures followed for Absolute and Relatve QoS Dfferentaton provson and management both n a statc and n a dynamc base. The system was appled on a real network testbed and t performed well succeedng n satsfyng the ADC and/or RDC related constrants posed each tme. Drectons for future work nclude but are not lmted to the realzaton of further wde scale trals so as to experment wth the applcablty of the framework presented herewth. References: [1] P.P Whte, "RSVP and Integrated Servces n the Internet: A Tutoral," IEEE Comm. Mag., pp , May [2] K. Nchols, S. Blake, F. Baker, and D. Black, "Defnton of the Dfferentated Servces Feld (DS Feld) n the IPv4 and IPv6 Headers," RFC 2474, Dec [3] S. Blake, et al., "An Archtecture for Dfferentated Servces," RFC 2475, Dec [4] I. Stoka and H. Zhang, "LIRA: An approach for Servce Dfferentaton n the Internet," IProc. NOSS-DAV, [5] C. Dovrols and D. Stlads, "Relatve Dfferentated Servces n the Internet: Issues and Mechansms," ACM SIGMETRICS Performance Evaluaton Revew, vol. 27, no 1, June [6] MANTRIP Del. D2.1: System Requrements and Hgh Level Archtecture. [7] M.Breugst and T. Magedanz, "On the Usage of Moble Agents n Telecommuncaton Envronments," Proc. 5th Conf. On Intellgence n Servces and Networks 1998 (IS&N 98), May [8] M. Breugst and T. Magedanz, "Moble Agents Enablng Technology for Actve Intellgent Network Implementaton," IEEE Network, vol. 12, no. 3, Aug [9] B Tetelbaum, " QBone Archtecture (v1.0)," Internet2 QoS Workng Group Draft, Aug [10] A Beszczad, B. Pagurek, and T. Whte, "Moble Agents for Network Managng," [11] W. Carpe, G. Cybenko, K. Mozum, and R. Gray, "Network Awareness and Moble Agent Systems," IEEE Comm. Mag., July [12] J. Dale, "A Moble Agent Archtecture to Support Dstrbuted Resource Informaton Management," [13] S. Jamn, S. Shenker, and P. B. Danzg, "Comparson of Measurement-based Admsson Control Algorthms for Controlled-Load Servce," Proc. INFOCOM '97, Aprl [14] A.M. Odlyzko, "Pars Metro Prcng: The Mnmalst Dfferentated Servces Soluton," Proc. of IEEE/IFIP Internatonal Workshop on Qualty of Servce, June [15] D. Clark and W. Fang, "Explct allocaton of best-effort packet delvery servce," IEEE/ACM Transactons on Networkng, vol. 6 no. 4, Aug

6 Proceedngs of the 10th WSEAS Internatonal Conference on COMMUNICATIONS, Voulagmen, Athens, Greece, July 10-12, 2006 (pp ) [16] C. Dovrols, D. Stlads, and P. Ramanathan, "Proportonal Dfferentated Servces: Delay Dfferentaton and Packet Schedulng," IEEE/ACM Transactons n Networkng, Feb [17] K. H. Leung, J. Lu, and D. Yau, Characterzaton and Performance Evaluaton for Proportonal Delay Dfferentated Servces, In Proc. of Internatonal Conference on Network Protocols (ICNP), Oct [18] S. Floyd and V. Jacobson, "Lnk-sharng and resource management models for packet networks," IEEE/ACM Transactons on Networkng, vol. 3, no. 4, Aug [19] ITU-T Rec. X.739, Informaton Technology - Open Systems Interconnecton, Systems Management Functons - Metrc Objects and Attrbutes, [20] ObjectSpace Inc. Web ste, May [21] B. Cho and R. Bettat, "Effcent Resource Management for Hard Real-Tme Communcaton over Dfferentated Servces Archtecture", Proc. of the 7th IEEE RTCSA, Cheju Korea. Dec [22] C. Cetnkaya, V. Kanoda, and E. Knghtly, "Scalable Servces va Egress Admsson Control," IEEE TRANSACTIONS ON MULTIMEDIA: Specal Issue on Multmeda over IP, vol. 3, no. 1, March [23] M. Louta and A. Mchalas, "Qualty of Servce Management n IP networks through Dynamc Servce Rate Reconfguraton", to appear n Journal of Internet Technology. [24] M. Louta, A. Mchalas, E. Loutas, and V. Loumos, "Qualty of Servce Management n IP networks", Proc. of 7th Internatonal Conference on Telecommuncatons ConTEL IEEE 2003, Zagreb, Croata, June [25] A. Mchalas, M. Louta and V. Loumos, "Effcent Call Admsson Control Methods n DffServ Archtecture," Proc. 12th IEEE MELECON 2004, Dubrovnc, Croata, May [26] A. Mchalas, P. Fafal, M.Louta, and V. Loumos, "Proportonal Delay Dfferentaton Employng the CBQ Servce Dscplne,", Proc. of 7th Internatonal Conference on Telecommuncatons ConTEL IEEE 2003, Zagreb, Croata, June 2003.