Broad Network Wide Statistics of TCP Indicators Measurement Reassume the Status of the Wireless 3G Network Monitoring
Abstraction—Numerous services of practical concern root from the potency to supervise amass packet-level hints in a Third Generation ( 3G ) web are unwanted traffic in the Internet is a well-known fact rule any web that has been engineered without taking its presence into history might see problem during periods of monolithic exposure during grand-scale monitoring. Among them, the likeliness to assume locate systems of web predicaments ( i.e. relentless deficit of keeping, or apparatus miss-functioning ) in the nucleus and wireless fragments use without consecutive entree to the contraptions. This system yields strong exercising convenient, given the charges and perplexity of utilizing web equipments, particularly in the radio Radio Access Network ( RAN ) . At the same clip, it pictures precise predicaments ( i.e. the demand to dynamically endemic the traffic beginnings ( Mobile Stations ) ) and theoretical troubles ( i.e. acknowledging engorged cells as of Routing Area degree TCP measurings ) . The writers hit-off on this work-in-progress aimed at carry throughing such setup on top of a extremely developed monitoring web system now extended in an operational web.
Keywords— GSM, UMTS, 3G, Passive web, RAN, TCP
Wireless systems of broad country public web are now traveling about towards Third Generation ( 3G ) Mobile systems, pulling to confirm package switched information applications. The Universal Mobile Telecommunication System ( UMTS ) has been espoused in Asia, evolved by 3G Partnership Project ( 3GPP ) as an development of Global System for Mobile Communication ( GSM ) . Two chief subdivisions are included in 3G web, ( I ) Radio Access Network ( RAN ) and ( two ) Packet Switched Core Network ( PS-CN ) where the interface between Radio Network Control ( RNC ) and PS-CN is called IuPS where Iu interface carry traffic ( like as voice and informations ) every bit good as control information, which is developed on the footing of Internet Protocol ( IP ) . Based on WCDMA holding been developed UMTS RAN ( UTRAN ) , several operators uphold at the same time General Packet Radio Services ( GPRS ) RAN developed from the heritage of GSM system, in Figure 01. A figure of UMTS webs became ready since 2003 while first GPRS maps day of the month back to 2000. Since so, the repute of developing 3G Networks and Services has enlarged the coverage country of accessing Internet to the geographical district, and going a cardinal concern of the comprehensive Internet in Asia. However the 3G atmosphere is still under development like in Bangladesh, at least along the undermentioned dimensions:
_ traffic capacities and subscriber population
_ terminal capablenesss and comparative incursion of the assorted terminal genres ( laptops with 3G card, French telephones, and so forth. )
_ applications portfolio and responsibilities offered by the agents
Technological betterments are still in the list of points of many operators like High Speed Downlink Packet Access ( HSPDA ) in the UMTS RAN, Enhanced Data Rate for Global Evolution ( EDGE ) in the GPRS RAN, IP Multimedia Subsystem ( IMS ) in the CN [ 1 ] . All these characteristics jointly build a possible for alterations in the worldwide traffic that can go on at the macroscopic degree ( network-wide ) and in a relatively short clip frame. Hence, the aptitude to exactly and comprehensively supervise the web standing and to early identify impetuss in efficiency and/or local jobs is a cardinal support of the web map and optimisation process. Monitoring system a wide-area web is non a simple occupation. First, the figure of ingredients is large and they are extended geographically. Second, for most prosaic grounds it is indispensable to utilize constellation parametric quantities ( i.e. provisioned bandwidth ) , logs and counters from ample web constituents, with dissimilar package and from dissimilar sellers, and considerable monetary values, complications and troubles are detected in pattern where it approaches to extraction, congregating and correlativity of like heterogenous informations ( i.e installation and keeping a monitoring substructure with consecutive entree to the web ingredients of the industry web is highly expensive ) . Furthermore, the coarseness and the quality of the informations accessible from the contraptions ( i.e built-in counters ) are frequently hapless and/or insufficient for in-depth survey of the web province.
In this research it is researching the feasibleness of supervising a production 3G web wholly by inactive whiffing packages on few key Core Network ( CN ) links, sole of direct usage to the contraptions. This attack yields a figure of practical benefits, and opens fresh farther chances for bettering the fabrication and operation of a existent web. For case, the merger of location informations extracted from the signaling sections with indexs of Transfer Control Protocol ( TCP ) public presentation ( i.e. Retransmissions Timeout ( RTO ) and Round Trip Times ( RTTs ) ) to supervise the existent public presentations of the full RAN, and to descry the require for place wireless re-optimization intercession, non including direct entree to the RAN equipments. This attack is correspondent in rule to passive web imaging. An extra value point of inactive monitoring, while attached with hint storage, is the likeliness to put to death post-mortem analysis of web jobs. Practical to 3G, it consents for open uping survey instructions unexplored so far, like the rating of the possible impact of unsought traffic ( i.e. worm infections, Denial Of Service ( DoS ) assaults ) onto the functionally complex 3G web substructure, or the analysis of signaling traffic to emerge balmy terminuss or web miss-behavior on the control panel. Although such attacks are non new in the general sense, however their application to the exact circumstance of 3G webs divulges new chartless aspects. In this part it is tried to edify the chances of fine-grain supervising a 3G web system, with a focal point on the problem of grand-scale packet-level public presentation monitoring. The writers report on the first proficient concerns and the unfastened points.
1. SETTINGS OF MONITORING SYSTEM FOR 3G
The mention web scenario ( GPRS/UMTS ) is depicted in Figure 01. As any other right to utilize web, the 3G web system has a hierarchal like tree deployment position. The Base Stations ( BSs ) and the Mobile Stations ( MSs ) are geologically nation-wide distributed. Traveling up in the hierarchy fact that at first Base Station Controller ( BSC ) / Radio Network Control ( RNC ) , afterwards Serving GPRS Support Node ( SGSN ) , in the terminal Gateway GPRS Support Node ( GGSN ) the degree of heed additions, is affecting increasingly a smaller figure of contraptions and physical locations. In fact, the GNinterface is fundamentally a wide-area IP web inter-connecting the different SGSN/GGSN sites, and such it embeds routers, IP subnets and so forth. In a typical web system there are relatively few SGSNs and even smaller figure GGSNs. Consequently it is likely to take a snapshot the whole information traffic from local users on a infinitesimal figure of GN/GIinterface links. Nevertheless, for some services it is necessary to entree the GB/IuPS interface nexus near the SGSNs. Besides, monitoring every interface requires the skill system to be capable of parsing and understanding the full 3G protocol suite, for both the signaling every bit good as user plane. The development of a grand-level inactive monitoring construction, including a parser for the full PS-CN protocol stack, and its execution in the activational web were implemeted within the METAWIN undertaking [ 2 ] , enabling to passively supervise all CN boundary lines interfaces ( GI, GN, GB, IuPS ) . Frames are taken with Data Acquisition and Generation ( DAG ) cards and certification with GPS synchronized time-stamps and large-capacity storage system like Home Location Register, a cardinal database that contains inside informations of each phone endorser, at the accessible cost. For privateness rudimentss traces are anonymized by hashing all evidences linked to user peculiarity at the 3G lower beds ( MSISDN- the telephone figure associated to each SIM, International Mobile Subscriber Identity ( IMSI ) , etc. ) , at the same clip as the user payload the TCP/IP bed is detached. As discussed, one key characteristic in several monitoring relevancy is the capacity to mention every package to the correspondent MS and to its bing wireless site ( i.e. at higher coarseness in a cell ) which is so called Routing Area ( RA ) . It is likely on the GNinterface to go through on packages to MS, but non to its site. Actually, when interchanging informations traffic MS are necessary to establish a logical nexus with the GGSN, the so called “PDP-context” is the 3G homologous of a dial-up connexion in a modem-based ISPs where IP references are dynamically assigned at the PDP-context acivation, which is maintained for the full activity clip ( runing from sub-second to few hours ) . The state of affairs of PDP is correspondent to a modem dial-up nexus in ISP webs. It is an important entity in the 3G kineticss, since a figure of intents are executed on a per-PDP state of affairs footing ( i.e. the handing over of IP reference, production of charging ticket ) and important parametric quantities of attending ( i.e. Access Point Name ( APN ) , QoS parametric quantities ) can be sniffed hardly throughout the PDP-context gap procedure. This monitoring system tracks these signaling sections and maintains state of affairs for every active PDP-context. It is capable to go through on each incoming package on GNto the PDP-context of matching and hence to the making MS. A figure degree of localisation is likely by whiffing on IuPS ( for UMTS ) and on GB( for GPRS ) , with different systems for the two owing to diverse protocol judicial admission. It is all the clip potency to know apart accurately the bing location of MS at the Routing Area degree ( a anthology of some immediate cells ) , for both UMTS and GPRS, besides for those MSs that are presently closed to the web but non concerned in active traffic exchange ( i.e. Updates of Routing Area ) . The localisation of finer-grain ( i.e. per-cell ) is likely in GPRS hardly for active MSs. As a consequence, it is possible in GPRS to go through on informations packages ( in uplink and downlink ) to the bing cell. In order to UMTS the localisation of per-cell of informations packages is non completed: as a MS displacement into a new Routing Area ( RA ) , hardly the first visited cell is hit away to the SGSN and can be therefore sniffed on IuPS interface. Following cell alterations within the RA are non “seen” on IuPS and hence are non well-informed by this monitoring system. This characteristic makes the occupation of uncovering cell-level jobs ( i.e. congestion ) more demanding in UMTS than GPRS, because the cells within a RA are non independently and accurately evident, hence necessitating extra illation processs. Last, based on the RA and/or local connexion information it is likely to tie in the packages captured near to the SGSNs ( on GB/IuPS ) to the present BSC/RNC, a footing for uncovering jobs or farther divergencies at the degree of these contraptions.
2. GRAND-LEVEL Monitoring PERFORMANCE IN 3G NEWORK SYSTEMS
Similarly to wired web system, TCP is the taking traffic component in the 3G web [ 3 ] . In position of the fact that TCP is closed-loop controlled, its activities depend on the state of affairs of the end-to-end way. For both the microscopic ( per connexion ) and macroscopic degrees ( per sum ) are accurate.
Tools have been developed to gauge several TCP public presentation indexs ( i.e. RTT, RTO ) by measuring the behaviour of entity links ( micro degree ) as of inactive hints ( i.e. tcptrace ) . Ideas were besides recommended to pull out arrows of anomalousnesss at the macro degree [ 5 ] . Broad web statistics of TCP arrows presume the position of the complete web system: over long time-bins of norm they can be exercised as man-made worldwide Cardinal Performance Indicators ( KPI ) , concerted for uncovering macroscopic impetuss in wide web parts ( i.e. owing to decelerate alterations of the international traffic allotment ) or for quantifying the existent development upon high-tech improves ( i.e. HSPDA, EDGE ) . For case, Figure 02 studies, in UMTS for one hebdomad in October 2010, legion TCP indexs deliberate the appraisal with past measurings does non unwrap any reasonable public presentation move after one twelvemonth, in malice of the significant enhance in traffic volume. When joined with routing information, these indexs can be applied to infer the attending of public presentation debasement points far-away from the monitoring point. This method, a signifier of “network tomography” , fits satisfactorily to the 3G Core Network owing to a measure of cardinal unusual features like tree construction, regularity of waies, divider between waiters ( on the GIside ) and clients ( the MS ) . This permits to supervise the definite value and the public presentations of 3G web at the package degree for the full CN, and to restrict abnormalities. Besides, the grouping of these indexs with the per-MS place informations removed from GB/IuPS hints makes it possible to go through on public presentation indexs to demand radio countries ( cells or RA ) , in order to construct “performance maps” in clip and infinite. As of there, one can use relatively easy setup for observing parts of persistent or perennial public presentation debasement, straight descrying hard countries. Some grade of numerical tax write-off is necessary to get the better of the deficiency of full per-cell declaration in UMTS, where correct maps are gettable hardly at the RA phase. The more connexion with “load maps” ( i.e. figure of active clients and/or transmitted volume per cell ) would be utile for know aparting between likely grounds, for case troubled wireless coverage against deficiency of wireless capableness, and so trip local engagement ( radio re-optimization ) . The world-wide statistics can be discriminatory by some MSs sing highly hapless transportation conditions. To eschew false dismaies, cautiousness is necessary to know apart state of affairss whereas the hapless public presentations are responsible to MS-specific state of affairs instead than to country broad position. The problem can be expressed in conformity with statistic tax write-off and hypothesis testing, an attractive characteristic for explore. Additionally, the fiting with mobility informations will supply insight into the pattern forms and TCP public presentations of traveling MSs for the period of handovers.
The radical prospective of the propounded technique in position of the wireless optimisation method should be explicit in 3G Network at least to those who are holding cognition of the modern-day pattern in this respect. Without utilizing to the RAN contraptions including that this attack is required but hardly to the GB/ IuPS near the SGSNs, typically co-located at a little figure of physical sites. So far, it is established the likeliness to put a constriction connexion within the Core Network from hints together with few vantage ends on GN[ 6 ] . The MS-tracking has been already applied, individually for GPRS and UMTS, correspondingly on GBand IuPS. The extension to the RAN, i.e. per-cell measurings of TCP, necessary some farther developments to the analysis instrument ( a customized edition of tcptrace ) to run cell study. In the linked posting some statement opening measurings of Retransmission Time Out ( RTO ) and TCP Round-Trip-Time ( RTT ) frequences in peculiar GPRS cells, depended on past hints. The beginning outcomes stipulate that in GPRS the figure of MS aboard active in the same cell is highly low. This makes farther disputing to know apart public presentation debasement owing to cell fortunes from MS-specific problems. A likely attack would be so to tie in cell measurings across diverse times ( yearss ) and research for marks of “recurrent” public presentation debasement.
- P. Svoboda, F. Ricciato, E. Hasenleithner and R. Pilz, “Composition of GPRS/UMTS traffic: snapshots from a unrecorded web, ” Vienna Univ. of Technology, Inst. of Communications and Raio-Frequency Engineering, submitted to IPS-MOME.
- F. Ricciato, P. Svoboda, J. Motz, W. Fleischer, M. Sedlak, M. Karner, R. Pilz, P. Romirer-Maierhofer, E. Hasenleithner, W. Jager, P. Kruger, F. Vacirca, M. Rupp, “Traffic monitoring and analysis in 3G web: lessons learned from the METAWIN undertaking, ” Elektrotechnik & A ; Informationstechnik, 123/7/8, pp. 288-296, 2006.
- J. Bannister, P. Mather, S. Coope atOrbitage Advisers, “Convergence Technologies for 3G Networks, IP, UMTS, EGPRS and ATM, ” John Wiley & A ; Sons, Ltd, England, 2004.
- Fabio. Ricciato, Francesco. Vacirca, Philipp Svoboda, “Diagnosis of Capacity Bottlenecks via Passive Monitoring in 3G Networks: an Empirical Analysis, ” ftw. Forschungszentrum Telekommunikation Wien, Technical Report, FTW-TR-2006-008.
- A. Abouzeid, S. Roy, “Stochastic Modeling of TCP in Networks with Abrupt Delay Variations, ” Journal of Wireless Networks, Vol. 9, Issue. 5, pp. 509-524, 2003
- P. Benko, G. Malicsko, A. Verse, “A Large-scale, Passive Analysis of End-to-End TCP Performance over GPRS, ” Vol- 3, pp. 1882-1892, Proceedings of IEEE Infocom 7-11 March 2004, Hongkong, China