CC BY
65
QUESTIONS OF THE ORGANIZATION
AND MODELS OF FUNCTIONING OF MODERN
INFOCOMMUNICATION NETWORKS
Burenin Andrey Nikolaevich,
Ph.D., associate professor, chief specialist of JSC «Research Institute «Rubin», St. Petersburg, Russian, [email protected]
Legkov Konstantin Evgenyevich,
Ph.D., deputy head of the Department automated systems of control, Military Space Academy, St. Petersburg, Russian,
Levko Igor Vladimirovich,
Ph.D., senior lecturer of the Department automated systems of control, Military Space Academy, St. Petersburg, Russian,
Keywords: infocommunication system, infocommunication network, level network, base level, intermediate level, infrastructure level, flow models.
Based on the analysis of the main directions of development of information systems and telecommunications networks concluded about the need for their convergence in infocommunication system or network (ICS). It is necessary to fully and timely meet the the needs of users of various levels in information and telecommunication services with the required U level of stability and security.
q; The ICS developed and created at present are substantially different from each other and from the general appearance co of the perspective ICS. To provide information and telecommunication services used by many software and hardware. <C They allow officials of control centers to share any kind of messages and receive information services at a specified time and with the required quality.
This article describes the interaction and major organizational components of ICS. The variants of architectural description of ICS and it description by collection of network-level model are offered.
Basic models of flow requirements specific to each level of ICS and the properties of these flows are considered. The flow type is determined by the needs of the officials of the control centers and processes of functioning of the ICS. Based on the analysis the following conclusions were made. Any representation of the real requirements flows in level networks by stationary flow model (primitive, Palma, recurrent, recurrent delay, Bernoulli, generalized self-similar, etc.) must be scientifically justified (on their use in dynamic models of level components of ICS). So flow models comprises a much more complex models that describes the states of the communication and server equipment, level networks and ICS as a whole.
Now within developing communication systems of different function the structures intended for full and timely satisfaction of needs of users of a various rank in information and telecommunication services with ensuring of steady and safe functioning of these structures in the conditions of natural and artificial hindrances, failure and equipment damage, and also strengthening of information influences of various violators more and more distinctly are allocated. As such structures expansion of so-called infocommunication networks on the basis of modern technical, technological and organizational solutions [1, 2] is reasonably planned.
Wide information of the processes occurring in various corporations and departments, leads to introduction of a set of the information and directory systems realizing demanded information technologies, departments ensuring functioning of them and divisions. Along with the information processes, processes of integration of corporate or departmental information, directory systems in uniform infocom-munication networks (ICS) in which granting to users and means both information, and telecommunication services is carried out in recent years became essential is unified by the corresponding hardware-software complexes of the services supported by a wide range of telecommunication
networks as a part of ICS. Thereby it is provided granting to all users of a full range of the services connected with exchange of information, its transfer, delivery and consumption, and also processing, storage and accumulation.
As a rule, various ICS, being a part of the Uniform network of telecommunication (UNT) of the Russian Federation, essentially differ from each other needs for resources, scope, structure, possibilities, real capacity, and also safety and stability.
At the same time, a telecommunication basis of many corporate or departmental communication systems now are outdate (so-called, inherited) secondary communication networks while the modern telecommunication kernel of these systems only is created.
Shape, the nomenclature and the main characteristics of existing (inherited) secondary networks of many communication systems was defined as features of construction of communication systems of the Russian Federation in former years, and processes of creation and UNT Russian Federation expansion.
Along with development of corporate networks of a speech transmission and data, in recent years the past and at the beginning of a present century projects on expansion of the modern telecommunication networks focused on an exchange of speech and data, integrating various networks of data transmission, a documentary exchange, telephone and cable systems and intended for association of existing networks on the basis of the ISDN, FR, IP and MPLS technologies over SDH or ATM [1-3] were at different times carried out.
Appeal of use of these technologies to convergence of existing communication networks is determined as their functional completeness by granting to users of the services necessary for maintenance of modern of information, and existence of a wide profile of samples of switchboards and routers both of domestic development and production, and foreign. Besides the combination of these technologies meets the requirements of openness on strengthening of services and extension of the list of supported network technologies, that is creates necessary conditions for creation of a modern telecommunication kernel of ICS, taking into account transition in a mobile radio communication to communication networks of the 4th and 5th generations.
At the same time, ICS developed and created now, despite the general tendency of their construction according to concepts of networks of the following generation (NGN) and global information infrastructure (GII), depending on features of their application, from shown requirements for ensuring information security, often essentially differ from each other and from the general shape of perspective ICS.
So, in some of created ICS partially or principles of broadband digital networks with integration of services (B-ISDN), with connection of information systems as users are substantially realized.
The main lack of ICS constructed on concept B-ISDN, that they can be created only separately from existing networks is, and at their expansion it is necessary to replace
almost in one stage all park of the out-of-date network equipment that in practice extremely is not favorable and realizable only for certain financially successful customers.
Therefore B-ISDN did not receive wide application both in corporate networks, and in networks of the general using (them the Internet and the Internet essentially pressed similar networks).
Therefore prospects of creation of ICS are connected with concepts of GII and networks of the following generation (NGN networks), thus as ICS we will understand the concept of creation of the infocommunication systems providing granting an unlimited (increased) set of information and telecommunication services with flexible possibilities on their management, personalisation and creation of new services at the expense of standardization of the information and network decisions, assuming realization of a universal transport network with the distributed switching, removal of functions of providing information and telecommunication services in terminal network knots and integration with traditional and existing communication networks.
Basis of architectural creation of ICS is the transport network (as a rule, two-level), access networks, knots of information services, knots of telecommunication services and knots of management of services.
In modern ICS the two-level transport communication network entering into their structure, is multiprotocol and provides transfer of different types of information with use of various protocols of transfer (ATM, FR, IP-MPLS, MPLS over ATM), i.e. realizes universal service of transfer which consists in transparent information transfer of users between the network terminations (access networks) without any analysis or processing of its contents.
For providing information services and services of telecommunications in ICS numerous hardware-software means are used, which allow users to exchange any kinds of messages (speech, video, data) to receive information services at any time and with the set quality. Means of ICS also allow to unify procedures of providing access to info-communication services for various users, and also to organize gateway interaction with users of other networks.
Conceptually ICS should include four organizational components (fig. 1):
- users who are sources and recipients of information and services, use this information for the organization of the daily activity;
- information devices (information appliances) which are used for storage, data processing, and provide access to information and services;
- the communication infrastructure which carries out information transfer between geographically remote information devices (it can be presented in the form of a transport network and access networks);
- actually information which includes, first of all, a video information, speech, data, and also the applied software (the user appendices), allowing to convert the message from an original form (speech, the image, computer graphics, video) in the electronic form available to use by other users.
Fig. 1. Interaction of the main a component infocommunication system
Platforms of support of communications - this terminal equipment of data, modems, devices of access of different function, Ethernet switchboards, routers etc.
As accessors the DSL access line, a network of a cable television, the optical line of access, the radio communication channel, the satellite channel, the radio access line are used a subscriber line of communication to automatic telephone exchange or the digital switchboard.
As the ICS telecommunication networks are used: telephone system of communication of the general using, primary communication network, networks of data transmission of various standards (X.25, FR, ATM, IP-MPLS), restrictedly Internet. All listed program and the IKS hardware components, and also the services rendered on their basis, are objects of management of an automated control system (ACS) of ICS.
The structure of ICS connects among themselves in a whole network resources, storage and data processing devices, and also resources of the intermediate software to offer users standard services and to support their applications. Means of ensuring of information security belong to these means within ICS, calculations for rent of paths at UNT Russian Federation, and also means of system management (network management and management of services). Without participating directly in information transformation from one form in another, means of the intermediate software allow to regulate this process, providing optimum distribution, security and controllability of the ICS network resources.
Information services and services of telecommunications, and also appendices of users are under construction of separate components - construction blocks. Presence of these or those a component defines properties and possibilities of ICS resources.
Within ICS all services are characterized by transactions which are carried out by the user at service inquiry/ activation. Thus appendices of the user allow to get full driver's license on use of this service, under condition of an authorized access.
Users can use infocommunication services of directly or by means of the user appendices. Thus all components of the
user appendices should be supported in ICS, which, as well as services, usually unite in packages to create for the specific user demanded difficult service or to provide access to the appendix. The general structure of the services provided in ICS within its functional architecture, is given on fig. 2.
The traditional telecommunication services provided by ICS, as a rule, offer users of technology for access to knots of concrete services, but can support and appearing new telecommunication services (except for base services) while the information technologies being a basis of information services, offer use of the user appendices only for the access/the organization of concrete services. In ICS networks convergence of all elements is step by step carried out as already today to get access to the majority of new communication services it is impossible without the user appendices (Internet browsers, post programs, appendices for coding and a speech transmission on IP networks).
The range of services which are usually provided within modern ICS, is rather wide. It can dynamically change together with change of available resources. Therefore it is often expedient to classify certain components of services, rather than services. Thus each component of service depends on a resource necessary for its support.
In the whole ICS makes set of databases, means of processing of information, cooperating communication networks and a set of terminals of users. Thus access to the ICS information resources is realized by means of the services of the new type which have received the name of infocommunication services. It is supposed that they will prevail in ICS of perspective communication systems already in the near future.
Now the main development of infocommunication services for the majority of inhabitants of the countries is carried out within the computer Internet, access to which services is carried out through providers and traditional communication networks. At the same time in most cases services the Internet, in view of a full disclosure of this
Fig. 2. Multilevel functional architecture infocommunication system
network, lack of demanded level of safety and functioning guarantees in the emergency situations, limited possibilities of users provided to changing appendices do not meet their requirements. In this regard development of info-communication services is carried out with simultaneous expansion of functionality of networks as a part of ICS.
To the main technological features distinguishing info-communication services from services of traditional communication networks, it is possible to carry the following:
- infocommunication services appear at top levels of model of interaction of open systems (OSI) while services of traditional networks are provided at representative, session, transport and network levels;
- the majority of infocommunication services assumes existence of a client part and server; the client part is realized in the equipment of the user, and server - on the special allocated ICS hub called by knot of services;
- infocommunication services, as a rule, assume information transfer of multimedia which is characterized by high speeds of transfer and asymmetry of entering and proceeding information streams;
- difficult multipoint configurations of network connections are often necessary for providing infocommuni-cation services;
- for infocommunication services a variety of applied protocols and possibilities on management of services is characteristic from the user;
- for identification of subscribers of infocommunica-tion services additional addressing within this infocom-munication service is, as a rule, used.
The majority of infocommunication services are "appendices", their functionality is distributed between the equipment of "supplier" of service and the terminal equipment of the user. As a result, functions of the terminal equipment also should be carried to structure of infocom-munication service that it is necessary to consider at their regulation.
The model defining participants of process of providing of infocommunication services and their relationship, also differs from model of traditional services of telecommunication in which three main participants were presented only: operator, subscriber and user. The new model assumes existence of the entrusted service provider which renders infocommunication services. Thus the supplier is the consumer of services of the transfer provided by the ICS transport network.
The generalized information architecture of perspective ICS is presented on fig. 3. The basis it is made by a universal transport network and the networks of access realizing functions of transport level and level of management of switching and transfer.
Into structure of a transport network enter:
- the transit knots which are carrying out functions of transfer of information and switching;
- the terminal (boundary) knots providing access of subscribers to services of a transport network;
- the controllers of the alarm system which are carry-
ing out functions of processing of information of the alarm system, management of calls and connections;
- the locks, allowing to carry out connection of traditional communication networks;
- flexible multiprotocol switchboards (softswitch).
Controllers of the alarm system can be taken out in the
separate devices intended for an service of several knots of switching. Use of the general controllers allows to consider them as uniform system of switching and the alarm system, distributed on ICS networks. Such decision not only simplifies algorithms of establishment of connections, but also is the most economic for providing all services as allows to replace expensive systems of high-capacity switching small, reliable, flexible and available at cost.
Terminal/terminal-transit ICS transport network knots, in principle, can carry out functions of knots of services, i.e. the structure of functions of boundary knots can be expanded at the expense of addition of functions of granting enough simple telecommunication services and for creation of such knots the technology of flexible switching (Soft Switch) which also allows to coordinate various systems of the alarm system can be used.
Infocommunication services assume realization on the basis of functional model of the distributed (regional) databases. Access to databases will usually be organized with LDAP protocol use. Thus the concept of creation of ICS in many respects leans on the system and technical solutions which have been already developed by the international organizations of standardization.
The solution of numerous problems of design, creation, expansion and management of ICS is possible only in the presence of their rather correct formalized description with use of the certain mathematical designs reflecting key parameters and laws of functioning, essential to achievement of the purposes for which achievement ICS are created.
The ICS model grows out of formalization of system and its elements, i.e. constructions accurate formal (in an ideal, mathematical) their description with necessary extent of approach to reality [3]. The essence of formali-zation is in general reduced to the following. As ICS mathematical model and its elements define dependence of characteristics of conditions on parameters, first of all it is necessary to solve a question of a choice of set of characteristics and parameters. As characteristics of conditions it is expedient to choose such functions which, on the one hand, would provide convenience of determination of required sizes at research ICS and its elements with a modeling method, and with another - would give the chance to receive enough their simple mathematical model. The choice of the parameters characterizing process of functioning of ICS, is caused by those factors which should be considered at formalization of process [3]. However, as a rule, there is no possibility to specify any formal rules for a choice of characteristics of conditions and parameters of studied ICS that, in turn, excludes from consideration the questions connected with completeness and uniqueness of system of characteristics [3, 4, 6].
Fig. 3. The Generalized information architecture perspective infocommunication system
Essential influence on process of functioning of ICS is rendered by random factors. For the formal mathematical description of various casual objects of ICS it is expedient to use likelihood schemes of casual events, random variables and casual processes [4-8].
At the same time, the accounting of the factors, which influence is not defining for an assessment of characteristics and parameters of a network and its elements, will bring only to that mathematical models become too bulky and badly foreseeable, and accuracy of the solution of tasks thus practically does not increase [6, 8].
As in quality a basis of the purpose of creation of ICS is representation to users of various information and telecommunication services of demanded quality, as its base logic model the multilevel functional architecture represented on fig. 2 can be taken. At this ICS it is expedient to present the three-level network model which each level is set by a certain network of the services, rendering the fixed services of concrete level of ICS: infrastructure, intermediate and base, fig. 4.
Each level network of services is described by the count of G(YA,Hb), G(JA,Eb) and G(RA,Qb), representing model according to a network of services of infrastructure, intermediate and base levels of ICS.
The ICS models entered by consideration level infrastructure, intermediate and base components (IL, MWL and BL) define its functioning in the conditions of various
casual and deliberate influences, characterizing its such important property as stability. Thus as models of stability of ICS in the plane of its level representation the following expressions can be offered:
P{ f [Qic (Vic, Gc,Uc)] > flc} > PIC,
(1)
where f[QIC(VIC, G U )] — functional of quality of functioning of IC ICS;
QIC(VIC, G UC) — the stochastic function characterizing process of functioning of IC ICS;
V G C — respectively fixed and indignant parameters (characteristics) of functioning of IC ICS;
G IC=yIC(Ifl, IRV, IKA), and Ifl, IRV, IKA the indignations characterizing impact on IC ICS respectively of casual and deliberate hindrances, refusals and computer attacks.
P{f \qmwc (vmwc , GMWC,UMWC
)] — fMWC } — PMWC , (2)
)]- functional of quality of
Mwcy mwc Gmwc Umwc) - the stochastic function char-
where f[QмWC(VMWC, GMWC UMWC
functioning of MWC ICS;
QMWC(VM
acterizing process of functioning of MWC ICS;
VMWC, GMWC — respectively fixed and indignant parameters (characteristics) of functioning of MWC ICS;
GMWC = VMWC(Zfl, ZRV, ZKA), and Zfl, ZRV, ZKA — the indignations characterizing impact on MWC ICS respectively
of casual and deliberate hindrances, refusals and computer attacks.
P{f [Qbc (Vbc , Gbc ,Ubc )] — fBC}
— PBC
(3)
where f[QBC(VBC, GBC, UBC)] - functional of quality of functioning of BC ICS;
QBC(VBC, GBC, UBC) — the stochastic function characterizing process of functioning of BC ICS;
VBC, GBC — respectively fixed and indignant parameters (characteristics) of functioning of BC ICS;
GBC=VBC(Vfi: VRV VKA)' and Vfl' VRV VKA the indignations
characterizing impact on BC ICS respectively of casual and deliberate hindrances, refusals and computer attacks.
Thus work of ICS we will consider steady if inequalities (1) — (3) are carried out.
The most convenient and complete description of standard structure of each level of ICS is reached by representation it in the form of corresponding the column G (Y, B), which set of tops of Y = {Y3 ..., Y, ..., Y,, ..., YN}, and a set of arches of B = {bij}. The capacity of a set of B depends on degree of connectivity of knots of level and cannot exceed size 0,5N(N-1). To each element bij of a set of B quite certain pair (Y, Y) e Y is put in compliance.
In turn, to each element Y e Y is put in compliance a certain knot of a network of level, and to the element
b . e B — a certain branch of this network. To each arch
ij
the column bij e B is attributed the size lij equal to weight of a branch of a network of level of ICS, connecting the
Y hub with the Y hub. Besides, to each arch b.. the set of
i , ' ij
K.. = {. k..,, ..., k.„ ..., k. } which element k... is equal to
ij *-by ijV ' ijf ' ijmJ ijc ^
number of virtual channels with the corresponding capacity vij{ ,is put in compliance.
The structure of each level of ICS can be set also various matrixes. The matrix of connectivity of the level network D «m» of ICS allows to describe connections of knots
cm
of a network of level with each other. Under condition of a fairness of virtual channels in branches it is a symmetric square-law matrix of an order of N:
= \d..
d.. = 0,
« '
h Vm=L2,3
(4)
Fig. 4. Three-level network model of infocommunication system
first of all, processes of receipt and service of requirements of rendered services of various services and services of each functional level. It is represented perspective these processes proceeding on each of three functional levels of ICS to describe mathematically uniformly in the form of the corresponding models of service [4-8]. Differently, (IL, MWL or BL) ICS connected with processing of information it is expedient to present each element of an infrastructure, intermediate or basic level to MWL the model of service described by expression for probabilities of a condition of each module of service of level or ICS components:
dPo(t,m,«) _ dt
■■- Po(t, m, «)l(m, «) + u Pl(t, m, «);
dP' m « = (i + 1)Mm«P+1(t, m, j) - iMmjP, (t, m, j) + Mm, j)P-(t, n, «), (5) dt
dp (t, m, j)
dt
-"Mm, jPn (t, m, j) + l(m, jPh (t, m, j)
Weight factors of branches of each network of level of ICS it can be set by a matrix of L = | lij | which each element is equal to weight of the branch connecting the Y and Y, hubs.
The qualitative and quantitative structure of branches of a network of level of ICS can be described by a set of matrixes of capacity K = {Kf} which element represents
a matrix of number of virtual channels K, = | k.. J.
i 1 iji'
Thus, the structure of a network of level of ICS is represented a set of matrixes of structure of S = {L , K , V }.
m ^ m m mJ
Owing to final reliability and survivability of complexes and the equipment of an level network, its structure does not remain invariable. Separate virtual channels and knots of an level network can fail and be restored. Therefore the structure of a network of each level of ICS will constantly change in the course of its work.
Special difficulty at the mathematical description of ICS is played by models of processes proceeding in it, and
j = 1....,Nm; m = 1,2,3
where A(m, j) and pmJ— according to intensity of receipt of requirements of service and service of requirements;
P (t, m, j) probability of finding of the module «j» of service of level «m» of architecture of ICS (m=1, 2, 3 respectively for BL, MWC and IC) in the corresponding condition.
According to (5) dynamic models of each element «i» of a base component, element «k» of an intermediate component and element «r» of the ICS infrastructure component it is possible to present as the modules of service described by systems of the stochastic differential equations, respectively expressions:
dP0BC (i, t )
dt
-PoBC (i, t )Abc (i) + Mbc (i ) PBC (i, t );
(6)
dp"(i)i''t ) = -n(i )mbc (i )p„bbc)(i, t ) + ¿bc (i)p„bbc)-i(i, t ).
dt
- P0MWC(k,t)^Mffc(k) + Ммас(к) РГс{кЛ
.рл«г,, Ч
аг0 ^ ft, i ) _ dMWC Пг /: .. t h \ DMIVC/■ dt
,pUWCч
' ' - -n.\.. ! 1,\ r>MWC,,, , 1 ll,\T>MWC,
(7)
dt
dP0C (r,t) _
dt
dP'1 )(r, t )
dt
= -n{k)»MWC{k)PZ (k,t) + A,uwc{k)P„J):l(k,t)
-If (r, t)X,c (r) + ц,с (r)P 'C (r, t %
n(r)Vcc (r)PZ)(r, t ) + kc (r ) PChl(r, t)
(8)
In models (6)-(8) setting entrance processes are flows of requirements of receiving services with intensities
^Wi =1 .., «ВС, AMWC(k)Vk =1, .., nMWa AI0(r)Vr =1, .., nIG
and days off — flows of messages of the service which intensity are defined by probabilities Pn%(i,t),P^(k,t), P%rr,t).
To complete the picture it is necessary to consider base models of flows of the requirements typical for each of levels of ICS.
Flows of requirements, characteristic for a network of each level of ICS decide on the one hand by needs of users, and on another - processes of functioning of ICS. The main properties of flows of requirements are important.
The stationarity or nonstationarity is one of the main properties of flows of the requirements characterizing dependence of their likelihood testimonials from of time.
Other property of information streams is absence, partial presence or presence of aftereffect which characterizes likelihood development of process of receipt of requirements depending on background.
And, at last, the third property of flows of requirements is the ordinariness or the absence of ordinariness characterizing possibility of receipt at the same time of several requirements.
The important characteristic of the streams circulating in each ICS level network, function of distribution of a time interval between two next arriving requirements and dependence or independence of random variables of time intervals between two arriving requirements is.
According to the given properties and characteristics of flows of the requirements circulating in the ICS level networks, the most applied when modeling processes in it, are: primitive (or stationary) stream; stream of Palm; stream of Erlang; recurrent stream; a recurrent stream with delay; stream of Bernulli; self-similar (or fractal) stream; non-stationary stream.
The primitive information stream possesses all three properties, i.e. it is ordinary, stationary and without aftereffect. For this stream the probability of that on time site t will arrive exactly k of requirements (messages, packages, shots, cells), is defined by the following expression
P {N (t ,t) = k} =
ake k!
(9)
Naturally the model of a primitive information stream though it is rather often used by researchers and designers of networks owing to its simplicity and sufficient accuracy of reproduction of real internodal streams, by their consideration in settlement tasks for the so-called periods of the greatest loading, in case of ICS it not always adequately reflects real processes of receipt of requirements in dynamics of functioning of ICS in which as show supervision, loading constantly changes, and in the ICS separate networks (is more often in a number of networks of a basic level and an intermediate level) effects of grouping of requirements and aftereffect (i.e. a stream loses property of ordinariness and absence of aftereffect) are quite often shown.
Stationary, ordinary information streams of Palm are more the general streams regarding an assumption of limited aftereffect. In order that it was possible to call information stream a stream of Palm it is necessary and enough that this stream was a recurrent stream at which functions of distribution of periods between two arrived requirements F(t) = P{t < t} satisfied to a ratio
Fl(t) = kjl -F (u)du
(10)
In this plan the primitive stream is also a stream of Palm at which time intervals between the next arriving requirements are distributed equally under the indicative law and are independent among themselves. Thus, the stream of Palm, excellent from primitive, is formed when intervals between the next arriving requirements (messages, packages, shots, cells) are represented by random variables with excellent from indicative the distribution law.
In a stream of Palm of an event of receipt of requirements can come only during the so-called "defiant" moments.
Special case of a stream of Palm are a stream of Erlang. A «k» order stream of Erlang with parameter X is the stream of Palm at which intervals between arriving requirements are distributed under the «k» order law of Erlang. As a rule, the stream of Erlang turns out from a primitive stream at its «sifting» through service knot at which in an initial primitive stream only each «k» the requirement remains, and all the others remain (or jump out) in service knot. In such stream At(k) between two next requirements it is possible to present time interval in the form of the sum of k of the independent random variables distributed on the indicative law with parameter X:
At( k > =21-
(11)
where a = At, and A - intensity of a stream.
The primitive stream and stream of Palm are special cases, so-called recurrent streams with the delay, defined by functions of distribution F1(t) = P{t1 < t} and F(t)=P{Tk<t}Vk =2, .., n (for a primitive stream F(t)=1 - e-Xt,
and for a stream of Palm - Fl(t) = A jl -F (u)du).
0
If t1, t2, ..., - the moments of receipt of requirements, zk = tk - tk1, k > 1; t0 = 0, transformation of Laplas-Stiltyes of the corresponding functions of distribution will become:
f1(s) = Me-sz; f (s) = Me-szk, k > 2 Fn(t) = P{tn < t}, fn(s) = Me-z, n > 1
As t = z,
n 1
.+z , and z,..., z
n 1 ' n
(12)
sizes independent
in aggregate,
fn(s) = fi(s)[ f (s)]n-1 , n > 1.
(13)
Having used the device of making functions it is possible to receive:
7l(r,i) =
(14)
41-*/(*)]
If information stream is purely recurrent (i.e. F1(t) = F(t) ),
7z(z,s) =
s[\-zf(s)}
(15)
(16)
(At) = J [1 + m(At - x)]dF(x) =
0
a t
= F(At) + J m(At - x)dF(x).
(18)
77(z,A0 = n[l + (z-l)í}(Aí)]
(19)
where F(At) = j f (t)dt, a f (t) - density of receipt of
0
requirements.
Then the probability of receipt in the range of exactly i of requirements (messages, packages, references, multimedia of data) will make:
p=nt1+(z-1)F'(At > ]
J-1 z
(20)
For i = 1, 2, ....., k these probabilities are defined by
expressions:
P = P y FÁAt) .
P = Po 1 - f(Aty
The corresponding expression for a stream of Palm takes a form:
Y=1 '
p = y Fr(At) Fj (At) . 2 0 [1 -Fy(At)j1 -Fj(At)]'
(21)
For a recurrent stream the probability of that in the range of time duration At will arrive exactly k of requirements, is equal
At
Pk(At) = JPk_,(At - x)dF(x) . (17)
0
The population mean of number of requirements of the recurrent stream falling on an interval in length At, is determined by a formula:
Pk =n Fr (At).
Y=1
In the simplest type stream of Bernulli, when [(At)- over 0 < t < At|
f (t) =
0
(22)
the probability of receipt exactly r of requirements in an interval [0, Ax] will make:
At
Pk (At) = G¡ 1 — 111 - —
A t
At
A t
(23)
In certain cases arriving on knots of the networks which are a part of ICS, real flows of requirements, it is possible to set model of a stream of Bernulli. Such stream turns out, for example, at collection of information from the subordinated elements a component and when collecting confirmations on performance of teams of management. Bernulli flow is such information stream, in which requirements arrive independently from each other, but unlike a primitive stream, at which the source of requirements (messages, packages, references, multimedia of data) is considered infinite, in stream of Bernulli their number is fixed, and each requirement surely will occur in this interval. Making function of number of requirements (messages, packages, references, multimedia of data) for stream of Bernulli will make:
j=i
In recent years, loading research for some networks which are a part of ICS, such as the Ethernet networks, ISDN subnets by a packet transmission of the user's interfaces given on channels D, networks of the all-channel alarm system of Construction Department No. 7, the ATM network by video transfer with variable speed and in some other cases, allowed to find the phenomenon of structural similarity of statistical characteristics of package loading at its measurement in different time scales (self-similarity or fractal properties). As the main property of a self-similar stream - preservation of structure of autocorrelation function regardless of parameter of aggregation of a stream of m, is obvious that properties of self-similarity arise in the course of transformation of a bit stream to a stream of cells more often.
The correlated stationary likelihood process N (nk, k=1, 2, 3...) with function of autocorrelation KN(k) it can be transformed to new temporary sequence N(m)(ni(m), 1 = 1,2,3...) with autocorrelation function z(m)(k) by a way
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of averaging of initial sequence of N on not being crossed consecutive blocks in the size of m.
Process (stream) of N is called as precisely self-similar (or fraktaloobrazny), if z(m)(k) = z(k) for all m = 1,2,3; k=1,2,3 and if compound process become N indistinguishable from process concerning their functions of autocorrelation. Such properties all processes with fractal properties possess. However difficulties of modeling and calculation of switching systems, servers and other elements of service of each level of ICS on which streams with fractal properties arrive, result in complexity, and a thicket and to impossibility of their formal description. It should be noted that properties of self-similarity (fractal) some known streams, for example, stream of Bernulli which it is possible to consider as a special case of a self-similar stream possess also.
Thus, the approach offered in article to the description of modern ICS in the form of multilevel network architecture, allows to present each functional level model of a network of services, and each functional component of service of concrete level — system of the stochastic differential levels which are setting dynamics of its conditions.
At the same time, it is necessary to consider that any representation of real flows of requirements of service in the ICS level networks model of a stationary stream (primitive, stream of Palm, recurrent, recurrent with delay stream of Bernulli, generalized self-similar etc.) should be scientifically proved in respect of their use in dynamic models level an ICS component since models of streams enter into much more difficult models describing conditions of the switching and server equipment, and also level networks and ICS as a whole.
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For citation:
Burenin A.N., Legkov K.E., Levko I.V. Questions of the organization and models of functioning of modern infocommunication networks. H&ES Research. 2015. Vol. 7. No. 6. Pp. 70-79.
ВОПРОСЫ ОРГАНИЗАЦИИИ МОДЕЛИ моделями обслуживания требований на получение услуг
ФУНКЦИОНИРОВАНИЯ СОВРЕМЕННЫХ уровня ИКС.
ИНФОКОММУНИКАЦИОННЫХ СЕТЕИ Рассмотрены базовые модели потоков требований,
характерных для каждого из уровней ИКС, и свойства
Буренин Андрей Николаевич, этих потоков. Вид потока определяется потребностями
1-. Санкт-Петербург^, Россия, konferenciа_аsu_vkа@mаi|.ru должностных лиц пунктов управления и процессами функ-
Легков Константин Евгеньевич, ционирования самой ИКС.
г. Санкт-Петербург, Россия, [email protected] На основании проведенного анализа сделаны следующие выводы. Любое представление реальных потоков
Легко Игорь Владимирович, требований на обслуживание в уровневых сетях ИКС
г. Санкт-Петербург, Россия, [email protected] моделью стационарного потока (примитивного, Пальма,
рекуррентного, рекуррентного с запаздыванием,
Аннотация Бернулли, обобщенного самоподобного и т.д.) должно
На основе анализа основных тенденций развития инфор- быть научно обосновано в плане их использования в
мационных систем и телекоммуникационных сетей сделан динамических моделях уровневых компонент ИКС. Так
вывод о необходимости их конвергенции в инфокоммуни- как сами модели потоков входят в значительно более
кационные системы или сети (ИКС) с целью полного и сво- сложные модели, описывающие состояния коммутацион-
евременного удовлетворения потребностей пользовате- ного и серверного оборудования, а также уровневых
лей различного ранга в информационных и телекоммуни- сетей и ИКС в целом.
кационных услугах с обеспечением требуемого уровня
устойчивости и безопасности. Ключевые слова: инфокоммуникационная система, Развернутые и создаваемые в настоящее время ИКС суще- инфокоммуникационная сеть, уровневая сеть, базовый ственно отличаются друг от друга и от общего облика пер- уровень, промежуточный уровень, инфраструктурный спективной ИКС. Для предоставления информационных и уровень, модели потоков. телекоммуникационных услуг используются многочисленные программно-аппаратные средства. Они позволяют Информация об авторе:
должностным лицам пунктов управления обмениваться Буренин А.Н., к.т.н., доцент, главный специалист любыми видами сообщений и получать информационные ОАО «Научно-исследовательский институт «Рубин»; услуги в заданное время и с требуемым качеством. Легков К.Е., к.т.н., заместитель начальника кафедры авто-В данной статье приведено описание и взаимодействие матизированных систем управления Военно-космической основных организационных компонент ИКС.Предложены академии имени А.Ф. Можайского; варианты архитектурного построения ИКС и ее описание Левко И.В., к.т.н., старший преподаватель кафедры автосовокупностью сетевых уровневых моделей, моделей матизированных систем управления Военно-космической устойчивости уровневых компонент и укрупненными академии имени А.Ф. Можайского.
Для цитирования:
Буренин А.Н., Легков К.Е., Левко И.В. Вопросы организации и модели функционирования современных инфокомму-никационных сетей. Наукоемкие технологии в космических исследованиях Земли. 2015. Т. 7. № 6. С. 70-79.
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