Modeling and Assessment Performance of OpenFlow-Based Network Control Plane

Transcription

1 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): Modelng and Assessent Perforance of OpenFlo-Based Netork Control Plane Saer Salah Al_Yassn Assstant Teacher, Al_Maon Unversty College Abstract: The subject of the paper s the features of netork archtecture that bult on the concept of Softare-Defned Netorkng (SDN). The an councatng processes of OpenFlo protocol are deterned. OpenFlo s one of the ost coonly used protocols for councaton beteen controller and forardng eleent (OpenFlo stch) n SDN. Effcency characterstcs of an OpenFlo-based netork are also dentfed. Matheatcal tools and analytcal odel for analyss and evaluaton such characterstc as perforance and relablty of OpenFlo-based netork are also suggested n the paper. The proposed odel s based on queryng theory (M/M/1 queues consdered) and dstrbuton nforaton odels. The evaluaton perforance and relablty of netork s analyzed due to capture the nteracton beteen the OpenFlo stch and controller. The average packet executed te, sojourn te, atng probablty etrcs of control plane are suggested for evaluaton. Keyords: Softare-defned netorkng, OpenFlo protocol, perforance, blockng probablty, analytcal odel. 1. Introducton Today any bg corporatons and organzatons are beng used cloudng coputng technology. Cloud coputng gves opportunty to ncrease aount of dfferent types of servces, busness and users applcatons. Therefore, ultple applcatons are beng grated fro tradtonal desktop solutons to centralzed Web-based ones. Hoever, tradtonal coputng netorks not ready to solve all tasks that connected th effectve anageent of ultples dstrbuted applcatons (tradtonal routers and stches should antan and handle any dfferent types of protocols). A ne paradg that called softare-defned netorkng (SDN) as created to solve these probles. SDN propose to splt the control plane fro the data plane [1]. In ths ay, any ne opportuntes opens n the area of cloud coputng. The an advantages of SDN are a flexble adaptaton of netork resources to the servces requreents, netorks vrtualzaton, centralzed anageent process, reote adnstraton, etc. Hoever, the centralzed anageent echans faces a nuber of challenges: the nuber of processed requests and qualty of servce depend on the speed of type of controller (query processng, load dstrbutng). Accordng to the requreents of specfcaton controller s a key eleent that deternes the perforance of the ajor part of cloud coputng [2]. For exaple, to of the ost coon used SDN controller create quote delays of around 0.01 llseconds and a throughput flos per second (NOX) and offers delays of around 0.06 llseconds and a throughput of around 31,000 flos per second (POX). To effectve future functonng of the SDN netorks should to be analyzed such characterstcs as perforance and relablty. Also the Focus Group of Cloud coputng have been forulated requreents to the qualty of servces n such types of netorks [3]. These characterstcs depend prarly on the nuber of controlled stches and routers, ntensty of the ncong requests and processng te by the controller and provde the approprate qualty of servce. In ths ay portant to odel the controller-stch nteracton for the perforance analyss of SDN netorks. The odelng of SDN netorks and perforance estaton ll help to the anser questons such as ho any applcatons and data can be transferred, hat s the packet sojourn te, hat s the bottleneck n a netork. Thus, the odelng processes for SDN-based netork and evaluaton perforance, relablty of netork that bult on SDN concept are portant objects for ne desgned netorks archtecture and exstng netork too. 2. Overve of SDN. Openflo Protocol The SDN archtecture conssts of tree an eleents: a controller centralzed eleent, a stch ddle forardng devse (softare progra or hardare devce that forards packets) and end node custoer s devses (vrtual achne, oble devses, coputer etc) [1]. End node devses belong to data plane, controllers and stches to control plane of SDN archtecture. The effectve nteracton beteen controller and stches be able due to OpenFlo protocol [4]. The OpenFlo s a core of Softare-Defned Netorkng. OpenFlo protocol enables controllers to deterne the path and ethod to pass packets through the netork of stches [5]. The protocol offers a hgher flexblty n the routng of netork flos and the freedo to change the behavor of a part of the netork thout nfluencng other traffc. On the stch, there s a flo table, hch atches packets to ts entres based on ther source, destnaton Ethernet address, IP address or port, IP type of servce, ICMP code/type, VLAN ID or ncong port [6]. The controller s a softare process that lstens for OpenFlo essages. The Fgure 1.1 depcts the coon SDN or OpenFlo-based netork archtecture and nteracton beteen eleents. Paper ID: SUB

2 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): Fgure 1.1: Softare-Defned Netorkng archtecture Accordng to requreent of OpenFlo protocol specfcaton the controller-stch nteracton takes place as follos: 1) Packets fro end devses arrve to the stch port. 2) Stch checkng the atch entres; 3) Stch lsted n the relevant flo table entry are executed f the atch s fnd n flo table. The actons avalable are forard or drop packets; 4) Stch sent packet to the controller f the atch s not fnd n flo table; 5) The controller coputes the forardng path and updates the requred nodes n the data path by sendng entres ll add to the flo tables. 6) Subsequent packets of the flo are forarded based on pre-calculated forardng decsons and do not need any control plane acton. The Fgure 1.2 represents the general nteracton process beteen eleents of SDN archtecture (an OpenFlo-based netork). Fgure 1.2: General nteracton process OpenFlo protocol has a set of requests that should be take nto account durng desgned ne SDN-based netork. Ths set s processng at the SDN control plane: ontorng and evaluaton of the netork state, recovery after treats, netork confguraton upgrade [7]. Intalzaton process or ne packet REQ s alays the ntal phase of nteracton hen addng ne netork eleents or change the confguraton. More often controller s a bottleneck of the netork. Hoever, stches can add delay to the nteractng process and reduce perforance greatly too. Therefore, tt s portant to odel the controller-stch councaton and nteracton for the perforance analyss of OpenFlo netorks. 3. The Model of Openflo-Based Netork Most of the exstng researcher orks [8-10] are based on sulatons or experentatons. Despte ths, analytcal odelng s a te effcent alternatve. Analytcal odelng gves opportunty to experent thout takng uch te. It can be used for analyzng netorks and confdence that could be put n the obtaned results. The paraount portance to have an analytcal odel hch can capture the feedback nteracton beteen the controller and the stch, s able to odel any aount of traffc gong fro stch to controller (or controller to stch), and can be extended to ore than one stch [11]. The odels suggested n ths paper try to obtan all ths results. Paper ID: SUB

3 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): In the context of rando flo, calculaton of the degree perforance or netork load (characterstcs qualty of servce) s based on the probablty dstrbuton functons of the syste states. Effectve atheatcal apparatus developed for the analyss of systes that unfor chans and Markov processes. SDN netork lke all type of dstrbuted netorks can be odelng as systes th losses and systes th queres [12]. For systes th losses an nuercal characterstcs of QoS s blockng probablty ( P( B ) ). The blockng probablty s deterne as the rato of the aount of blockng or drop packets S B(t ) to the total custoer s packets arrvng at the sae te S(t ) : S B( t ) P( B ), (1) S( t,t ) 1 2 For the queung systes an nuercal characterstcs of QoS s probablty of custoer s packet arrvng and atng ( P, P 0 ). The probablty custoer s packet arrvng and atng s deterned as the rato of the aount of queung packets S Q(t ) to the total custoer s packets arrvng at the sae te S(t ) : S Q( t ) P. (2) S( t,t ) 1 2 Accordng to suggested, approach OpenFlo-based netork control plane layer (stch-controller nteracton) can be represented as a feedback-orented queung syste odel, dvded nto a forard queung syste and a feedback queung syste of the type M/M/1 [11]. The general odel of stch-controller nteracton depct on Fgure 2.1. P S( t ), (3) S( t ) 0 Where the average aount of equpent at the control plan of SDN archtecture, S( t ) - the ntensty of nput load (a packet flo). The arrval process at the stch s a cobnaton of the arrval process of packets receved fro the lne cards th rate λ and of packets beng forarded fro the stch buffer after the controller has deterned the approprate acton and the correspondng entry n the flo table as created. Let s assue that the queue length of the controller s lted ( Q ) n order to odel the possblty of dropped packets. The arrval rate n ths syste s p. A packet can be blocked at the controller th probablty p b. The drop packet can be queued n the stch and pass for a second te. Stch query te S s nversely proportonal to the nuber requests fro end node. Controller query te C s nversely proportonal to the nuber requests fro OpenFlo stch. The feedback controller queue used to odel the controller actually coprses out of the lneout card of the stch toards the controller, the buffer, and processng at the controller tself. The transsson te of packets fro the stch to the controller s encapsulated n the servce te of the controller. 4. Perforance and Relablty Evaluaton The proposed odel of OpenFlo nteracton s usng to evaluate perforance easures. The an characterstcs of odel of OpenFlo nteracton are: blockng probablty, the average packet executed te and suery delay te (stch proceedng delay te and controller proceedng delay te). Assued that the proposed odel has soe restrcton: The overall traffc arrval process at the stch and the controller s Poson. Further exponentally dstrbuted servce tes are used for the stch and the controller. Ths allos to use results based on M/M/1 queues. A packet has to traverse the stch syste at least once. Infnte buffer s assued at the stch,.e. stch don t drop packets. Requests are servced n accordance th the Frst Coe Frst Served servce polcy. Fgure 2.1: The odel of OpenFLo-based netork (stch-controller nteracton) The blockng probablty can be calculated accordng to the next forula: In the ntal state all buffer queues are epty. The probablty that controller or stch busy s P. Accordng to the requreents of QoS the [10]: 0 P 1. P Can be rtten as Paper ID: SUB P b S 1 0 S( t ) S( t ) S ( t ) S( t ) S( t ) S( t ) S ( t ) (4)

4 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): The average packet executed te ( E[ S(t )] s defned as the te spent by a packet n the netork fro the oent t enters the netork at ts source node, untl t leaves through the destnaton. E[ S(t )] for the SDN archtecture that depcted on Fgure 2.1 can be gven gven as: E[ S( t)] ( ). (5) S C Where 1 s average packet transsson te. The load ntensty (load per controller) can be represent as: ( S( t ) S ( t ))P ; P 1 Pb( C S ) C S b( N S ) So, probablty of custoer s packet arrvng and atng can be calculated as: 1 P, (7) 1 E[ S n( t )] Accordng to forula (6-7) sojourn te controller-stch can be rtten as: In proposed odel CS CS and NS should be analyzed. - ntensty nsde the stch-controller nteracton: CS 1 0 N ( S( t) S ( t)) P. NS - ntensty the stchnode nteracton: 2( S( t) S ( t)) P C S 0 In ths ay, the pockng probablty can be rtten as: ( S( t ) S ( t ))P 2 0 2( S( t ) S ( t ))P N S N S t ( S( t ) S ( t ))P 1 ( CS ) (6), (8) and sojourn te to packerts for the stch-controller nteracton odels (Fgure 2.1) can be rtten as: 1( S( t ) S ( t ))P ( СS ) 2( S( t ) S ( t ))P( N S ) P b( N S ) ( ). (9) CS N S As a result preposed a set of dfferent scenaros for proposed OpenFlo odels. The characterstcs of NOX controller ere consder durng calculaton. The an attenton take to the blockng probablty as ore portant characterstc of OpenFlo-based netork perforance. The Fgure 3.1 depcts the dependence of blockng probablty P b, 100% fro controller load, 100%. Proposed odel has a axu blockng probablty 0,006 n stuaton, hen controller load s axu and usng 65 End-nodes devces. Values are gven for controller loads fro 5 to 100 (edge eanng) percent n 10 percent steps. Therefore, controller handles the coplete traffc gong through the stch. Fgure 3.1: Ipact load controller ntensty to the blockng probablty Paper ID: SUB

5 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): Fgure 3.2 llustrates the odeled the depend of sojourn te of a packet on the controller load for an expected NOX controller servce te value of axu E[ S(t )] 530sec. Fgure 3.2: Ipact the load controller ntensty to the average packet executed te In Fgure 3.3 the coeffcents of varaton for the sojourn Dagras on the Fgure 3.2 are shon for several ntensty tes are shon also dependent on the controller load. Ths dstrbutons for dfferent aount of End-node devse and s caused by the fact that th a saller p. dfferent controller load. Accordng there dagres the average packet executed te s alost equal for dfferent ntensty and depend only fro controller load. As a result the total sojourn tes s dependng fro controller te delay. The less packets are subject to the delay posed by the controller and therefore, the devaton fro the ean value for these packets s uch hgher 5. Concluson Fgure 3.3: Sojourn te dstrbuton In ths ork e have proposed an analytcal odel for an OpenFlo enabled SDN based on M/M/1 netork. Proposed n the artcle OpenFlo-based odel of controllerstch nteracton can be used to estate the packet sojourn te and the probablty of lost packets n such a syste and can gve hnts to developers and researchers on questons ho an SDN archtecture ll perfor gven certan paraeters. As a result, perforance of OpenFlo-based odel as evaluatng. NOX controller characterstcs ere consder as an nput data. The applcablty of the odel s deterned by establshng tree perforance probablty easures: the blockng probablty (assued the orst varants hen Paper ID: SUB

6 ISSN (Onlne): Index Coperncus Value (2013): 6.14 Ipact Factor (2013): pb 0 ), the sojourn te dstrbuton (nsde controller and for all fragent), the average packet executed te (nsde controller). The artcle found these characterstcs dependng on the nuber of End node and the ntensty of the load that cong to the controller. Accordng to the obtaned result the sojourn te not ore than 3,7 s even for edge controller load. Thus, the presented odel helps to see the portance of the controller perforance for nstallng ne flos. References [1] N. McKeon, T. Anderson, H. Balakrshnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turner, OpenFlo: Enablng Innovaton n Capus Netorks, ACM SIGCOMM Coputer Councaton Reve, vol. 38, no. 2, 2008, - 69 p. [2] Archtecture SDN [Electronc resource] // Open Netorkng Foundaton. [2014]. Mode of access: [3] Softare-Defned Netorkng: The Ne Nor for Netorks [Electronc resource] // Open Netorkng Foundaton. [2012]. Mode of access: ads/sdn-resources/hte-papers/p-sdn-nenor.pdf [4] OpenFlo Stch Specfcaton (Seres) [Electronc resource] // Open Netorkng Foundaton. [2014]. Mode of access: [5] Tkachova Olena, Issa Saad, Mohaed Jaal Sal. Matheatcal ethods for analyss of Softare-Defned Netorks // Internatonal Journal "Inforaton Technologes & Knoledge", Vo9, 2, - pp [6] ONF, Open Netorkng Foundaton, [Onlne] Avalable: [7] P. Jogalekar, M. Woodsde, Evaluatng the scalablty of dstrbuted systes, Parallel and Dstrbuted Systes, IEEE Transactons on, vol. 11, no. 6, 2000, - pp [8] Azodololky, Saak Nejabat, Reza, Pazouk, Marya Seondou, Dtra. An Analytcal Model for Softare Defned Netorkng: A Netork Calculusbased Approach // IEEE Globeco, [9] Naous, Jad& Erckson, Davd & Covngton, G. Ada &Appenzeller, Gudo &McKeon, Nck. Ipleentng an OpenFlo Stch on the NetFPGA Platfor // Proceedngs of the 4th ACM/IEEE Syposu on Archtectures for Netorkng and Councatons Systes (ANCS 08), , - pp 1-9. [10] V. Tanyngyong, M. Hdell, and P. Sjodn. Iprovng PC-Based OpenFlo Stchng Perforance // 6th ACM/IEEE Syposu on Archtectures for Netorkng and Councatons Systes [Electronc resource], Ne York, NY, USA, 2010, Mode of access: [11] G. A. Korn, T. M. Korn Matheatcal Handbook for Scentsts and Engneers, McGra-Hll, Ne York, р. [12] F. Machhara, Transton probabltes of Markovan servce syste and ther applcaton. Rev. Elect. Coun. Labs. Vo.2/29, 1981, - pp Paper ID: SUB