Accelerating Call Route Query of Multi-domain SIP System via P2P GONG Jing, SHEN Qing-guo, SHEN Huan-sheng

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1 3rd Inernaional Conference on Mecharonics and Informaion Technology (ICMIT 2016) Acceleraing Call Roue Query of Muli-domain IP ysem via P2P GONG Jing, HEN Qing-guo, HEN Huan-sheng College of Communicaions Engineering, PLA Universiy of cience & Technology, Nanjing , China Key words:ip sysem;muli-domain;dn; P2P;no-worse-han-wo-hop query Absrac. Large IP Telephone sysem may conain muliple domains, and he delay of DN query across domains may be large. In his paper, he efficiency of call rouing in muli-domain IP sysem is improved by employing P2P echnology. The P2P-IP sysem archiecure is designed and a no-worse-han-wo-hop query algorihm is presened. The formulas for evaluaing he performance of he proposed soluion are derived. The efficiency of call rouing process can be effecively enhanced, and he insabiliy in he sysem operaion can be avoided. The proposed soluion can be applied o naional wide enerprises or organizaions. Inroducion The call conrol proocol IP (ession Iniial Proocol)[1] has only wo kinds of eniies: IP user agens and IP servers. The IP servers can be a regiser server, a proxy server, and a redirecion server. The locaion server is used o sore and rerieve he user's poenial locaion informaion, and i is no a formal funcional eniy of he IP sysem. UA (Agen User) represens a erminal sysem, which includes he clien (UAC) and server (UA). The regiser server (Regisrar) is used o process he regisraion reques for he IP UA. I records he URI (Uniform Resource Idenifier) and IP address of he IP UA. The regiser server is usually locaed in he same physical eniy wih he proxy server or he redirecion server. The proxy server is a funcional eniy ha is boh a clien sending reques and a server receiving a reques. IP reques can be forwarded o he nex hop server hrough a number of proxy servers, and he proxy servers can handle reques or forward he reques o he nex hop server. If necessary, he proxy servers will inerpre he reques message and even override he reques message. The nex hop server may be anoher proxy server, or he end user agen. The redirecion server is used o deermine he address of he nex hop server ha will process he call in he IP domain, and respond he clien wih he address of he nex hop server. imple IP sysem has only one managemen domain, while complex IP sysem can have muliple managemen domains. They are called single-domain sysem and muli-domain sysem respecively. Each domain in muli-domain sysem has independen IP domain name and servers. The servers can process he call reques and connec he caller and collee inra he domain. The processing of iner domain call reques is compleed by he cooperaion of servers in various domains. ingle domain IP sysem is no suiable for large IP phone sysem. This is because he number of users is huge, performance boleneck is likely o happen in cenralized managemen sysem, and here is single poin of failure. Muli-domain IP sysem can be a good soluion o he above problems. E.g., in muli-domain IP sysem each sip domain can be isolaed securely. When a cerain domain is infeced wih viruses or aacked, ha domain can be emporarily isolaed, hus quickly solve he securiy problem. For he pariion of IP domains, hey can be divided according o he user disribuion in geographical scope, so as o comply wih he curren communicaion nework division principle, and making he inerconnecion and inegraion of differen neworks easy. When IP call is being processed in IP sysem, ENUM (Number Mapping Elephone) echnology is used o ranslae he phone number ino he user's domain name, and hen he domain name service sysem (DN) is used o obain he corresponding user domain server address [2]. In The auhors - Published by Alanis Press 222

2 he muli domain IP sysem, he DN server in each domain sores he IP server address in is domain. When he cross domain call happens, informaion search among muliple DN servers is needed, and he delay may be large. o he P2P echnology can be used o improve he query efficiency. A presen, he IP phone sysems (sof swiching or IM) implemened by some radiional elecom manufacurers and operaors are capable o spor he hierarchical muli-domain seings. However, as o he srucure of he muli-domain sysem, query efficiency and oher issues, here are lile quaniaive analysis and sysemaic researches. The academia has sudied applicaion of P2P echnology in IP sysems, and made a number of echnical soluions in improving call queries and call handling efficiency, speed and reliabiliy [3]. IETF also gives he relevan sandards [4]. Bu muli-domain problem has no ye direcly involved in hese sudies and sandards. Ref [5 ] designed a localiy-aware P2P-IP sysem wih query hops complexiy being O(logN), bu is research on muli-domain is only wih wo-ier srucure, and more levels of IP sysem is no considered. Ref [6] designed a media communicaion mechanisms based P2P and IP combining. I used a hierarchical srucure for he P2P-IP overlay nework, and proposed relaed algorihm wih O(logN) query hops complexiy. Bu i sayed on an absrac fully disribued model, and did no analyze he physical disribuion of acual IP muli-domain sysems, he hierarchy and he domain name resoluion mechanism. Is applicabiliy in pracical IP muli-domain sysem is no high. In his paper, according o he applicaion requiremens and organizaion disribuion characerisics of he large IP elephone sysem, he hierarchical srucure of muli-domain IP sysem is presened. The DN based call rouing mechanism and is shorages are analyzed. The muli-domain IP sysem is improved by he use of P2P echnology. The call roue query algorihm no worse han wo hops is given. The algorihm is analyzed quaniaively by he ypical user disribuion and he raffic saisical model. Archiecure of Muli-Domain IP ysem Concep of Absrac ervice Node in IP ysem The muli-domain IP sysem consiss of muliple single domain IP sysems. Each IP single domain sysem has a variey of IP servers (proxy server, locaion server, ec.). We use a absrac service node o represen hese servers in he single domain IP sysem, and he nework of service nodes consiues he core of he IP sysem. ervice nodes can be composed of muliple funcional eniies, for example, one service node in a cerain domain can be composed of IP proxy server and locaion server. Hierarchical rucure of Muli-Domain IP ysem According o he demand of large IP elephone applicaions, he IP muli-domain sysem can be divided ino several levels, and each level can have muliple domains. Each domain has service nodes such as IP servers. Users wihin he domain are managed by domain IP server managemen, wih username expressed in form of URI (Uniform Resource Idenifier) elephone numbers: user-name-prefix@muli-level-domain-name. And he query and localizaion of one user is refined level by level by he collaboraion of IP redirec server, locaion server and proxy server based on domain name suffix. As o he naional-scale muli-domain IP sysem in China, i can be designed as he hree level srucure, as shown in Fig. 1. A he op plain, he 32 provincial-level regions are mapped in he firs level, he op level is composed of 32 domains. A he middle plain, he ciies of one province (e.g. Jiangsu province) is mapped in he second level, hey are he sub domains of a firs level domain in accordance wih adminisraion relaionship. Third level (i.e. he boom plain) can be se where appropriae. For a second level domain wih large number of users, he hird level domain can be se o serve he counies, disric, and insiuions, ec. Oherwise, if he scope of a second level domain is small, no hird level domain would be needed. 223

3 According o he hierarchy of hese levels, he srucure of he domain name can be obained. For example, he domain names of Jiangsu, Nanjing, Jiangning are js, nj.js and jn.nj.js. Call rouing for muli domain IP sysem based on DN query Via summary of IETF IP sysem and IM call rouing process [7], i can be known ha here are wo kinds of rouing: he direc roue (IP server servicing he caller direcly forwarding he call reques o he called pary) and relay rouing (forwarding he call reques hrough IP relay server o he called pary). Direc rouing performance is beer han ha of relay rouing, bu he IP server needs o configure he IP server informaion in every domain and he managemen is complex. Relay rouing mehod is simple in managemen, bu he call delay is large. In case of large IP sysem, DN based on relay rouing can be used and relay number need be limied o reduce call delay. The DN server in each domain sores he address of he IP server in is domain. For he cross domain call, he caller domain DN may send queries o he mulilevel DN servers and he ime delay may be larger. E.g., when a user in Beijing call anoher user in Jiangning Disric, Nanjing, Jiangsu, he Beijing IP server send query o Beijing domain DN (DN.bj), and DN.bj query abou IP address of IP server responsible for he called user in Jiangsu domain DN server (DN.js). DN.js again send query o Nanjing domain DN server (DN.nj.js), DN.nj.js o Jiang Ning DN server (DN.jn.nj.js) in he query forwarding chain. Finally he called domain of IP server IP address is obained. Then Beijing IP server forwards he call reques o he Nanjing Jiangning IP server. In order o reduce he delay of searching informaion among mulilevel DN servers, he domain name / address informaion cache can be used. A firs-level DN caches he addresses of IP servers in all oher firs-level domains and he second-level domains direcly managed by i, in order o achieve high speed forwarding of he call requess. Each second-level domain DN can cache he DN address of is serior domain IP server and adjacen second-level domain IP server. In addiion, he address informaion cache can also be used in he area of a relaively large call flow. The radiional DN sysem has he shorcoming of non-srucured nework, poor scalabiliy and query rouing only in accordance wih he domains level by level. When he DN servers in he same level is excessive, he rouing hop number and mainenance coss can no be balanced, and he query efficiency for large-scale muli-domain IP sysem is low. Alhough he use of DN cache echnology can reduce he searching ime, bu here are sill shorcomings in cache daa consisency and cache efficiency. Especially, he cache daa consisency mainenance requires a cerain bandwidh overhead, and when he DN nework is in he presence of link insabiliy, he cache daa dae in real ime is influenced. Therefore, wih he characerisics of P2P echnology in disribued daa synchronizaion and search, he elephone number resoluion and query performance can be effecively improved. Disribued sorage and query in IP sysem based on P2P In muli-domain IP sysem, he delay o locae user is an imporan meric o measure he performance of he sysem. Theoreically, one hop look can ensure he fases user locaing, bu he coninue dae of rouing ables require an overhead of cerain bandwidh occaion. Especially when he sysem is in a relaively unsable sae, rouing able daes in one hop look sysem may make he sysem produce jier. And a large number of saisics show ha he raffic beween he nodes decreases wih he disance (geographical disance, adminisraive disance, ec.) increase [7]. Therefore, we design a no worse han wo hops look mechanism. In he proposed sysem, mainenance raffic bandwidh is low, and he insabiliy in sysem operaion is avoided. Meanwhile, he query for locaing a user can be finished eiher in one hop wih high probabiliy, or in wo hops wih low probabiliy. 224

4 Descripion of no worse han wo hops query Definiion 1: Node, is an eniy wih all is sofware and hardware resources for he purpose o provide services in he nework. Nework head, is he node ha has he righ o mainain a nework, denoed as s. Member node in a nework is he node ha does no have he nework mainenance righ. Definiion 2: he level-i subne, is he subnework mainained by an level-i head. The level-i subne head is a node in he level-(i-1) subne, wih i>1. A op-level subne, i.e. he level-1 subne, is he subne composed of he op nodes in he nework; i is in he op level of he nework opology, and here is no nework head. Definiion 3: In he level-i subne, for nodes q and p wih he IDs in P2P sysem being I P if Iq IP Iq and >, and q is he firs valid node afer p, hen q is called he successor node of p, and is denoed by successor ( p). The hierarchical opology of he muli-domain IP sysem based on P2P is shown in Fig.1. Beijing Node Jiangsu Node (Head of a level-2 subne) Firs Level Domains Nanjing (Head of a level-3 subne) Node level-2 subne (Jinagsu Province) econd Level Domains Jiangning Node level-3 subne (Nanjing Ciy) Member Node Third Level Domains Fig. 1 Hierarchical Topology of Muli-domain IP ysem Based on P2P The hierarchical opology design can mee he requiremens of he error isolaion and securiy, provide efficien cache and bandwidh uilizaion and realize he hierarchical sorage and access conrol. Furhermore, i can effecively alleviae he mainenance overhead brough abou by he increase of sysem capaciy. Therefore, in he no worse han wo hop look sysem, we adop a hierarchical opology approach. The whole nework is composed of several sub neworks, which form a hierarchical relaionship among hem. The per subne node being he lower subne head is responsible for mainaining lower subne size and membership changes. The opological organizaion wihin a subne can be more flexible. Full-mesh and chord ring [8] ec. can be used. In order o ensure any node can find he desinaion node in no more han wo hops, we only need o ensure ha he rouing able of any node in he subne of a cerain level includes informaion of all he nodes in ha subne, and all he nodes in he lower level subnes direcly or indirecly 225

5 managed by he subne. When a node in he subne of a cerain level joins or leaves he nework (laer we will denoe node joining or leaving he nework as an even), he successor node of he even generaing node deec he even firsly. Then he successor node informs he even o he subne head, and riggers he even disribuion in he subne. The subne head sends he even o he managing nodes in he per subne. In General, when a node p in he ik -h subne of he level- k (denoed by i i... ) 1 2 i k produces an even, is subsequen node successor ( p) firs deecs his even, hen sends he even noificaion message o he nework head s i i..., and riggers he even propagaion in he subne 1 2 i k i1 i2... i k. The Nework head s i i... will be periodically send he even noificaion message o he 1 2 i k per level subne head s j 1,2,...,k -1} i belonged. s = { s i 1 i2... i = j urure of Muli-Domain IP ysem Based on P2P The service nodes in he muli-domain IP sysem can be conneced as a P2P nework, which can be called muli-domain P2P-IP nework. The muli-domain P2P-IP nework are designed wih a srucure of hree levels: he op level subne (primary domain), middle subne (second level domain) and he boom subne (hird level domain). The service nodes, as he head of cerain subnes, sores informaion abou is subne nodes, and mainains node number/size and member change of he lower-level subne, and so on. In he op level, nodes are conneced by he way of Full-Mesh and back he informaion wih each oher. o do nodes in he middle level. In he boom level, he number of nodes may be grea, so he nodes can be conneced as a Chord ring. More deails abou he mechanism of hierarchical-srucured P2P model can be found in [11]. Mobiliy Managemen The user mobiliy can be spored by IP sysem. When an end user moves ino a new locaion in he IP nework, he user s UA will regiser is new IP address in is home Regisrar erver. Then he new IP address can be queried by oher UA via P2P service. The IP service node can also be spored by he IP sysem based on P2P. When a IP service node change is locaion and IP address, is ID based on is IP domain does no change in P2P-IP sysem. o he logical srucure of he P2P-IP sysem remains he same. Is new IP address is propagaed in he P2P sysem quickly, and can be queried by oher IP service node. Performance of Muli-domain IP ysem based on P2P Time Bound of Even Propagaion I akes some ime for an even o be delivered o all nodes. This leads o informaion inconsisence and node query error. We use f o represen he user query error probabiliy. In order o mee he consrain of sysem error raio, he propagaion ime of he even (he even from generaion o ransmission o he las node in he desired available nework) should have an per limi, denoed by o. According o he above analysis, we ge he formula (1), f * n o. (1) r where n is he sysem node number, r represens he even generaing rae. In accordance wih he foregoing analysis of evens dae propagaion mechanism, we have o = decec + max( l3, l2, + l1), where de ec is he ime i akes from even generaion o even deecion, l3 is even propagaion ime hroughou he Chord ring of he boom level subne. The boom subne head, which is a node in middle level subne, delivers even o oher nodes in middle level subne in ime inerval l 2, and repors even o he head of he middle level subne in ime inerval. imilarly, he middle subne head, which is a node in op level subne, delivers even o oher nodes in op level subne in ime inerval l1, where < l

6 Mainenance Traffic Analysis Now we analyze he required sysem mainenance raffic o ensure he wors wo-hop query. The sysem even message consiss of he message payload (m-bye) for even descripions and header (v byes). There are several main message ypes in he sysem: (1) hearbea message. Due o he dynamic characerisics of he nodes, when a node joins he nework, i will periodically send hearbea informaion o is successor nodes. Taking ino accoun ha he nodes in he middle and op level subnes are relaively sable, hear beaing cycle can be se relaively long, he hearbea message raffics in he middle and op level subnes can be negleced. (2) even message propagaing in he boom subnes. We assume ha even generaions on he boom subne are evenly disribued in he subne. A he boom subne, when he successor node deecs an even in he inciden node, i immediaely sends a message o he subne head. [9] proposed an inciden deecion and repor algorihm for EDRA based on chord. The algorihm can complee even spread hroughou a nework wih ime complexiy O(log(n)) (n being he node number), and has good load-balancing performance and low mainenance coss. In his paper, we use he EDRA algorihm for he spread of evens on he boom subne. (3) even message propagaing in he middle subnes. When an even is deeced in he boom subne, i is immediaely repored o he subne head in he middle level. The subne head will packe i in a message and send he message o all oher nodes wihin inerval l 2 in he middle subne. In addiion, he subne head needs collec he evens and repor o he middle subne head in he op level every seconds periodically. (4) even message propagaing in he op subnes. When an even is by he middle subne head in he op subne, i will packe i in a message and send he message o all oher nodes wihin inerval l1 in he op subne. Bandwidh Requiremen for a Typical Case We assume he subnes on he same level have he same size. We use k 1, k 2 and k3 o represen he sizes of subnes on he op, middle and boom levels. Then we have n= k3* k2* k1+ k2* k1+ k1. The formulas for evaluaing he raffics of he head of subne on he op, middle and boom levels are shown in able 1, where avg is he average online ime of he service node and θ is he even relay delay in a boom service node. Talbe 1 Evaluaing he Traffics from differen ources in he proposed ysem ource Uplink Traffic Downlink Traffic member node boom subne head middle subne head 2 * ( m + v) + v + ( 2* N msgs * v + r * m* θ ) /θ avg 2* k3 *( k avg * m + v) 2v + *( k 2 l 2 2 1) avg l1 v 2 * v avg + v + avg ( 2* N msgs * v + r * m* l 2 θ )/θ 2* k3 * ( k 2* m + v) 2v + *( k2 1) + v 2* k * k * m 2v 2* k * k * k * m v 2v * k + ( + )*( k 1) * k2 + *( k1 1) avg l1 v As an ypical case, he configuraion parameers can be se as follows: f=1%, n=10 4 ~10 5. The hearbea informaion is 1 second, and aking ino accoun he message loss we assume de ec = 2s. In he experimen, we ake k1 = 31, k2 = 10, m=20 byes,and v=40 byes. Form Equaion (1), i has o 50s. Because of o = decec + max( l3, l2, + l1), so l3, l 2 48s. Consrained by he requiremens of raional message overhead and < l 1, we se = 5s. According o ref [6], we 2* have l 3 θ = 9. 6 s. log2 k3 For a exreme case wih n=10 5, he link bandwidh requiremens for IP service nodes in 227

7 differen level wih heir average online ime being 24 hours are less han 1kbps. Wih he increase of he average online ime, even generaing raio r in he sysem decreases, resuling in bandwidh requiremens decreased. Conclusion In his paper, he hierarchal srucure and call rouing issues of muli-domain IP sysem are sudied, he shorcoming of call rouing mechanism based on DN is analyzed, and he efficiency of call rouing is improved via using P2P echnology o realize he no worse han wo hops rouing queries. The proposed muli-domain IP sysem soluion is suiable for large IP elephone sysems, can be applied o naional deparmens and enerprises. Because of is disribued, self-organizing and scalable feaures, he service capabiliies of P2P nework increase wih he nework size. P2P can effecively spread he load o ensure ha he voice qualiy is no lower han he radiional elephone nework. This aricle mainly uses P2P o improve IP call rouing opimizaion problem. As o using P2P feaures in disribued processing and cenerlessness o solve problems such as he single poin of failure and performance bolenecks of he exising IP sysems clien/server archiecure, is he direcion for furher research. Acknowledgemens This work was financially spored by he Naural cience Foundaion of China ( ). References [1] J. Rosenberg, H. chulzrifme, G. Camarillo, e al., IP:ession iniiaion proocol, RFC3261, IETF, [2] P. Falsrom, M. Mealling, The E.164 o Uniform Resource Idenifiers (URI) Dynamic Delegaion Discovery ysem (DDD) Applicaion (ENUM), RFC3761, IETF, April [3] K. ingh and H. chulzrinne, Peer-o-Peer Inerne Telephony using IP, in Proceedings of he Inernaional Workshop on Nework and Operaing ysems por for Digial Audio and Video (NODAV05),2005, pp [4] C. Jennings, B. Lowekamp, E. Rescorla, e al., REsource LOcaion And Discovery (RELOAD) Base Proocol, RFC6940, IETF, [5] C. Zhang, L. Gu, T. Ma, e al. Localiy-Aware Peer-o-Peer IP, in proceedings of IEEE Inernaional Conference on Parallel and Disribued ysems, [6] YANG De-guo ; WANG Hui ; WANG Cui-rong, e al. The Research of P2P-IP Hierarchy Based Communicaion Mechanism, JOURNAL OF NORTHEATERN UNIVERITY(NATURAL CIENCE), China, 2008, 29(12): [7] M. Poikselka, G. Mayer, H. Kharabil, e al., The IM: IP Mulimedia Conceps and ervices (3rd ediion), John Wiley & ons Inc, [8] I. oica, R. Morris, D. Karge, e al., Chord: a scalable peer-o-peer look service for inerne applicaions, Proceedings of ACM IGCOMM, 2001: [9] L. Monnera, C. Amorim, D1HT: A disribued one hop hash able, Proc. of he 20h IEEE Inernaional Parallel & Disribued Processing ymposium, [10] M. Vaughn, M. Chia, R. Wagner, A boom- raffic demand model for long haul and meropolian opical neworks, Opical Fiber Communicaions Conference(OFC), March 2003, Vol1:

8 [11] Wang Bin, hen Qing-guo, TIDE:Effecive and Pracical Design for Hierarchical-rucured P2P Model, Compuer Communicaions (Elsevier), July 2012, Vol35(13):