Recommendation E.600 TERMS AND DEFINITIONS OF TRAFFIC ENGINEERING Introduction This Recommendation provides terms and definitions for use in the field of traffic engineering. Traffic engineering includes measurements, forecasting, planning, dimensioning and performance monitoring. Traffic engineering has a goal of ensuring trafficability performance objectives for telecommunications services. Trafficability performance is one of the major factors in Quality of Service (QOS). Recommendation E.800 explains the relation of various Quality of Service factors and gives terms and definitions for Quality of Service concepts and for availability and reliability aspects. The purpose of this vocabulary is to aid in the understanding of traffic engineering and related Recommendations. The terms defined here may also be defined differently for applications outside the area of traffic engineering. Alternatives for the preferred terms are given following a semi-colon. LIST OF TERMS 1 General theory 1.1 Communication 1.2 Connection 1.3 Resource 1.4 User 1.5 Telecommunications traffic, teletraffic 1.6 Observed traffic 1.7 Poisson traffic; pure chance traffic 1.8 Peakedness factor 1.9 Smooth traffic 1.10 Peaked traffic 1.11 Traffic of volume 1.12 Erlang 1.13 Bid 1.14 Seizure 1.15 Idle (state) 1.16 Busy (state) 1.17 Release 1.18 Holding time 1.19 Blocked mode of operation 1.20 Delay mode of operation 1.21 Call congestion 1.22 Time congestion 1.23 Waiting time; queuing time 2 Calls 2.1 Call reattempt 2.2 Call intent 2.7 Call string 2.3 Call demand 2.8 Blocked call attempt 2.4 Call attempt 2.9 Abandoned call attempt 2.5 First call attempt 2.10 Successful call attempt; fully 2.6 Repeated call attempted; routed call attempt 2.11 Completed call attempt; effective call attempt 2.12 Successful call 2.13 Completion ratio 2.14 Answer seizure ratio 2.15 Answer bid ratio 2.16 Calling rate 2.17 Dialling-time 3 Circuits 3.1 Circuit 3.2 Trunk circuit 3.3 One way; unidirectional 3.4 Two way; bidirectional 3.5 Circuit group 3.6 Circuit subgroup 3.7 First choice circuit group 3.8 High usage circuit group 3.9 Final circuit group 3.10 Fully provided circuit group Fascicle II.3 - Rec. E.600 PAGE1 4 Grade of service 4.1 Grade of service 4.2 Quality of service variable 4.3 Dial-tone delay 4.4 Post-dialling delay 4.5 Answer-signal delay 4.6 Incoming response delay 4.7 Exchange call set-up delay 4.8 Through-connection delay 4.9 Internal blocking 4.10 External blocking 5 Traffic engineering 5.1 Busy hour 5.23 Route 5.2 Average daily peak hour 5.24 Traffic routing traffic 5.25 Call routing 5.3 Time consistent busy hour 5.26 Alternative route; alternate 5.4 Day to busy hour ratio route 5.5 Traffic carried 5.27 Network cluster 5.6 Traffic offered 5.28 Equivalent random traffic 5.7 Effective traffic 5.8 Overflow traffic 5.9 Blocked traffic 5.10 Lost traffic; abandoned traffic 5.11 Suppressed traffic 5.12 Origin 5.13 Destination 5.14 Traffic relation 5.15 Traffic matrix 5.16 Originating traffic 5.17 Terminating traffic 5.18 Internal traffic 5.19 Incoming traffic 5.20 Outgoing traffic 5.21 Transit traffic 5.22 Traffic distribution imbalance 1 General theory 1.1 communication F: communication S: comunicaci¢n Transfer of information according to agreed conventions. The information flow need not be bidirectional. 1.2 connection F: connexion S: conexi¢n An association of resources providing means for communication between two or more devices in, or attached to, a telecommunication network. 1.3 resource F: ressource S: ¢rgano Any set of physically or conceptually identifiable entities within a telecommunications network, the use of which can be unambiguously determined. 1.4 user F: usager S: usuario Any entity external to the network which utilizes connections through the network for communication. 1.5 telecommunications traffic; teletraffic F: trafic de t‚l‚communications: t‚l‚trafic S: tr fico de telecomunicaci¢n; teletr fico A process of arrivals and releases of demands for resources in a network. Note - The unit for the variable traffic is the Erlang (symbol: E). 1.6 observed traffic F: trafic observ‚ S: tr fico observado PAGE8 Fascicle II.3 - Rec. E.600 Instantaneous observed traffic is the amount of occupied resources at a given instant. Average observed traffic is the time average of instantaneous observed traffic over a given period. 1.7 poisson traffic; pure chance traffic F: trafic poissonnien: trafic de pur hasard S: tr fico poissoniano Traffic that has a Poisson distribution of arrivals. Note - Poisson traffic has a peakedness factor equal to 1. 1.8 peakedness factor F: facteur d'irr‚gularit‚ S: factor de irregularidad The ratio of variance to mean of a traffic. 1.9 smooth traffic F: trafic r‚gularis‚ S: tr fico con distribuci¢n uniforme Traffic that has a peakedness factor less than 1. 1.10 peaked traffic F: trafic survariant S: tr fico con distribuci¢n en pico Traffic that has a peakedness factor greater than 1. Fascicle II.3 - Rec. E.600 PAGE1 1.11 traffic volume F: volume de trafic S: volumen de tr fico The integral of the instantaneous traffic over a given time interval. Note 1 - Traffic volume is equal to the sum of the holding times of the resources. Note 2 - A unit used for traffic volume is the Erlang hour (symbol: E). 1.12 erlang F: erlang S: erlang The unit of traffic (symbol: E). In traditional telephony the number of Erlangs is the number of busy resources or the expected number of busy resources under stated conditions. 1.13 bid F: tentative de prise S: tentativa de toma A single attempt to obtain the use of a resource of the type under consideration. Note - In a network management context, the absence of a qualification implies a bid to a circuit group, a route or a destination. 1.14 seizure F: prise S: toma A bid that obtains the use of a resource of the type under consideration. 1.15 idle (state) F: libre S: reposo (estado de); estado libre Condition of a resource that is free to be seized. 1.16 busy (state) F: occup‚ S: ocupado (estado de) Condition of a resource following its seizure. 1.17 release F: lib‚ration S: liberaci¢n The event which changes the condition of a resource from busy to idle. 1.18 holding time F: dur‚e d'occupation S: tiempo de ocupaci¢n; tiempo de retenci¢n The time between the seizure of a resource and its release. 1.19 blocked mode of operation PAGE8 Fascicle II.3 - Rec. E.600 F: mode d'exploitation avec blocage S: modo de operaci¢n con bloqueo (de llamadas) A mode of operation in which bids which find no suitable resources idle and accessible are not permitted to wait. 1.20 delay mode of operation F: mode d'exploitation avec attente S: modo de operaci¢n con espera (de llamadas) A mode of operation in which bids which find no suitable resources idle and accessible are permitted to wait. 1.21 call congestion F: encombrement d'appel S: congesti¢n de llamadas The probability that a bid to a particular pool or resources will not result in an immediate seizure. 1.22 time congestion F: congestion temporelle S: congesti¢n temporal The proportion of time that a particular pool of resources does not contain any idle resource. 1.23 waiting time; queuing time F: temps de mise en attente S: tiempo de espera; tiempo de cola In delay mode of operation, the time interval between the bid for a resource and its seizure. 2 Calls 2.1 call F: appel S: llamada A generic term related to the establishment, utilization and release of a connection. Normally a qualifier is necessary to make clear the aspect being considered, e.g. call attempt. 2.2 call intent F: intention d'appel S: intenci¢n de llamada; intento de llamada The desire to establish a connection to a user. Note - This would normally be manifested by a call demand. However, demands may be suppressed or delayed by the calling user's expectation of poor Quality of Service performance at a particular time. 2.3 call demand F: demande d'appel S: demanda de llamada A call intent that results in a first call attempt. 2.4 call attempt Fascicle II.3 - Rec. E.600 PAGE1 F: tentative d'appel S: tentativa de llamada An attempt to achieve a connection to one or more devices attached to a telecommunications network. Note - At a given point in the network a call attempt is manifested by a single unsuccessful bid, or a successful bid and all subsequent activity related to the establishment of the connection. 2.5 first call attempt F: premiŠre tentative d'appel S: primera tentativa de llamada The first attempt of a call demand that reaches a given point of the network. 2.6 repeated call attempt; reattempt F: tentative d'appel r‚p‚t‚e S: tentativa de llamada repetida Any of the call attempts subsequent to a first call attempt related to a given call demand. Note - Repeated call attempts may be manual, i.e. generated by humans, or automatic, i.e. generated by machines. 2.7 call string F: chaŒne d'appel S: cadena de llamada All the call attempts related to a single demand. 2.8 blocked call attempt F: tentative d'appel bloqu‚e S: tentativa de llamada bloqueada A call attempt that is rejected owing to a lack of resources in the network. 2.9 abandoned call attempt F: tentative d'appel abandonn‚e S: tentativa de llamada abandonada A call attempt aborted by the calling user. 2.10 successful call attempt; fully routed call attempt F: tentative d'appel achemin‚e S: tentativa de llamada fructuosa; tentativa de llamada totalmente encaminada A call attempt that receives intelligible information about the state of the called user. PAGE8 Fascicle II.3 - Rec. E.600 2.11 completed call attempt; effective call attempt F: tentative d'appel ayant abouti; tentative d'appel efficace S: tentativa de llamada completada; tentativa de llamada eficaz A successful call attempt that receives an answer signal. 2.12 successful call F: appel ayant abouti S: llamada fructuosa A call that has reached the wanted number and allows the conversation to proceed. 2.13 completion ratio F: taux d'efficacit‚ S: relaci¢n respuesta/toma; tasa de compleci¢n; tasa de eficacia The ratio of the number of completed call attempts to the total number of call attempts, at a given point of a network. 2.14 answer seizure ratio (ASR) F: taux de prise avec r‚ponse (TPR) S: tasa de tomas con respuesta (TTR) On a route or a destination code basis, and during a specified time interval, the ratio of the number of seizures that result in an answer signal, to the total number of seizures. 2.15 answer bid radio (ABR) F: taux de tentatives de prise avec r‚ponse (TTPR) S: tasa de tentativas de toma con respuesta (TTTR) On a route or a destination code basis and during a specified time period, the ratio of the number of bids that result in an answer signal, to the total number of bids. 2.16 calling rate F: taux d'appel S: tasa de llamadas The number of call attempts at a given point, over a period of time, divided by the duration of the period. 2.17 dialling-time F: dur‚e de num‚rotation S: tiempo de marcaci¢n Time interval between the reception of dial tone and the end of dialling of the calling user. 3 Circuits 3.1 circuit F: circuit (de t‚l‚communication) S: circuito A transmission means which allows communication between two points. Fascicle II.3 - Rec. E.600 PAGE1 3.2 trunk circuit F: circuit (commut‚) S: circuito (entre centrales); circuito troncal A circuit terminating in two switching centres. 3.3 one way; unidirectional F: … sens unique; unidirectionnel S: en un solo sentido; unidireccional A qualification applying to traffic or circuits which implies that the establishment of a connection always occurs in one direction. 3.4 two way; bidirectional F: … double sens; bidirectionnel S: en ambos sentidos; bidireccional A qualification applying to traffic or circuits which implies that the establishment of a connection may occur in either direction. 3.5 circuit group F: faisceau (de circuits) S: haz de circuitos A group of circuits which are traffic engineered as a unit. 3.6 circuit subgroup F: sous-faisceau S: subhaz de circuitos A part of a circuit group with similar characteristics (e.g. type of signalling, type of transmission path, etc.). 3.7 first choice circuit group F: faisceau de premier choix S: haz de circuitos de primera elecci¢n With respect to a particular traffic relation, the circuit group to which this traffic is first offered. 3.8 high usage circuit group F: faisceau d‚bordant S: haz de circuitos de gran utilizaci¢n With respect to a particular traffic relation, a circuit group that is traffic engineered to overflow to one or more other circuit groups. 3.9 final circuit group F: faisceau final S: haz final de circuitos With respect to a particular traffic relation, a circuit group from which there is no possibility of overflow to another circuit group within the routing scheme currently in effect. PAGE8 Fascicle II.3 - Rec. E.600 3.10 fully provided circuit group F: faisceau totalement fourni S: haz de circuitos totalmente provisto With respect to a particular traffic relation, a circuit group which is the first choice circuit group for this traffic and which is traffic engineered as a final circuit group. 4 Grade of service 4.1 grade of service (GOS) F: qualit‚ d'‚coulement du trafic S: grado de servicio (GDS) A number of traffic engineering variables used to provide a measure of adequacy of a group of resources under specified conditions; these grade of service variables may be probability of loss, dial tone delay, etc. Note 1 - The parameter values assigned as objectives for grade of service variables are called grade of service standards. Note 2 - The values of grade of service parameters achieved under actual conditions are called grade of service results. 4.2 quality of service variable F: variable de qualit‚ de service S: variable de calidad de servicio Any performance variable (such as congestion, delay, etc.) which is perceivable by a user. Note - For a description of the relations of quality of service factors see Recommendation E.800. 4.3 dial-tone delay F: dur‚e d'attente de tonalit‚ S: demora del tono de invitaci¢n a marcas; periodo de espera del tono de invitaci¢n a marcar Time interval between off hook and reception of dial tone. 4.4 post-dialling delay F: attente aprŠs num‚rotation S: demora despu‚s de marcar; periodo de espera despu‚s de marcar Time interval between the end of dialling by the user and the reception by him of the appropriate tone or recorded announcement, or the abandon of the call without tone. 4.5 answer-signal delay F: d‚lai du signal de r‚ponse S: demora de la se¤al de respuesta Time interval between the establishment of a connection between calling and called users, and the detection of an answer signal at the originating exchange. 4.6 incoming response delay F: dur‚e de pr‚s‚lection S: demora de la preselecci¢n; duraci¢n de la preselecci¢n Fascicle II.3 - Rec. E.600 PAGE1 The interval from the instant when an incoming seizure is recognizable at the incoming side of the exchange to the instant when the proceed to send signal is sent to the preceding exchange by the receiving exchange. Note - This definition is only applicable in the case of channel associated signalling. 4.7 exchange call set-up delay F: dur‚e de s‚lection d'un commutateur S: demora de establecimiento de la comunicaci¢n por una central; tiempo de establecimiento de la comunicaci¢n por una central The interval from the instant when the address information required for setting up a call is received at the incoming side of the exchange to the instant when the seizing signal or the corresponding address information is sent to the subsequent exchange. 4.8 through-connection delay F: dur‚e d'‚tablissement d'un commutateur S: demora de transconexi¢n; tiempo de transferencia de una central The interval from the instant when the information required for setting up a through-connection in an exchange is available for processing in the exchange, to the instant when the switching network through-connection is established and available for communication. 4.9 internal blocking F: blocage interne S: bloqueo interno The probability that a connection cannot be made between a given point in a network and any suitable idle resource in an external pool of resources owing to call congestion within the portion of the network being considered. 4.10 external blocking F: blocage externe S: bloqueo externo The probability that a connection cannot be made between a given point in a network and any suitable resource in an external pool of resources owing to call congestion within the pool of resources. 5 Traffic engineering 5.1 busy hour F: heure charg‚e S: hora cargada The continuous 1-hour period lying wholly in the time interval concerned for which the traffic or the number of call attempts is greatest. 5.2 average daily peak hour traffic F: moyenne du trafic des heures charg‚es S: tr fico medio de las horas punta The average busy hour traffic of several days; it is usually not related to the same hour each day. PAGE8 Fascicle II.3 - Rec. E.600 5.3 time consistent busy hour F: heure charg‚e moyenne S: hora cargada media repetitiva o sistem tica The 1-hour period starting at the same time each day for which the average traffic of the resource group concerned is greatest over the days under consideration. 5.4 day to busy hour ratio F: rapport du trafic journalier au trafic … l'heure charg‚e S: relaci¢n del tr fico diario al tr fico en la hora cargada The ratio of the 24-hour day traffic volume to the busy hour traffic volume. Note - Busy hour to day ratio is also used. 5.5 traffic carried F: trafic ‚coul‚ S: tr fico cursado The traffic served by a pool of resources. 5.6 traffic offered F: trafic offert S: tr fico ofrecido The traffic that would be carried by an infinitely large pool of resources. 5.7 effective traffic F: trafic efficace S: tr fico eficaz The traffic corresponding only to the conversational portion of effective call attempts. 5.8 overflow traffic F: trafic de d‚bordement S: tr fico de desbordamiento The part of the traffic offered to a pool of resources which is not carried by that pool of resources. 5.9 blocked traffic F: trafic bloqu‚ S: tr fico bloqueado The part of the overflow traffic that is not carried by subsequent pools of resources.¦ 5.10 lost traffic; abandoned traffic F: trafic perdu; trafic abandonn‚ S: tr fico perdido; tr fico abandonado That part of the blocked traffic which does not result in reattempts. Fascicle II.3 - Rec. E.600 PAGE1 5.11 suppressed traffic F: trafic non exprim‚; trafic supprim‚ S: tr fico suprimido The traffic that is withheld by users who anticipate a poor quality of service (QOS) performance. 5.12 origin F: origine S: origen The location of the calling user. This may be specified to whatever accuracy is necessary. 5.13 destination F: destination S: destino The location of the called network termination. This may be specified to whatever accuracy is necessary; in international working, the area or country code is usually sufficient. 5.14 traffic relation F: flux de trafic S: relaci¢n de tr fico The traffic between a particular origin and a particular destination. 5.15 traffic matrix F: matrice de trafic S: matriz de tr fico A structured presentation of the traffic between a number of origins and destinations. 5.16 originating traffic F: trafic de d‚part S: tr fico de origen Traffic generated within the network considered, whatever its destination. 5.17 terminating traffic F: trafic d'arriv‚e S: tr fico de destino Traffic which has its destination within the network considered, whatever its origin. 5.18 internal traffic F: trafic interne S: tr fico interno Traffic originating and terminating within the network considered. 5.19 incoming traffic PAGE8 Fascicle II.3 - Rec. E.600 F: trafic entrant S: tr fico entrante Traffic entering the network considered, from outside it, whatever its destination. 5.20 outgoing traffic F: trafic sortant S: tr fico saliente Traffic leaving the network considered, destined for sinks located outside it, whatever its origin. 5.21 transit traffic F: trafic de transit S: tr fico de tr nsito Traffic passing through the network considered. 5.22 traffic distribution imbalance F: d‚s‚quilibre interne de trafic S: desequilibrio de la distribuci¢n interna de tr fico Unevenly distributed traffic among similar resources. 5.23 route F: voie d'acheminement S: ruta One or more circuit groups providing a connection between switching centres. 5.24 traffic routing F: acheminement de trafic S: encaminamiento de tr fico The selection of routes, for a given traffic relation; this term is applicable to the selection of circuit groups by switching systems or operators, or to the planning of routes. 5.25 call routing F: acheminement d'appel S: encaminamiento de la llamada The selection of appropriate circuit subgroups or individual circuits for a particular call attempt. 5.26 alternative route; alternate route F: voie d'acheminement d‚tourn‚ S: ruta alternativa A second, or subsequent choice route between two switching centres usually consisting of two or more circuit groups in tandem. 5.27 network cluster F: faisceau de faisceaux Fascicle II.3 - Rec. E.600 PAGE1 S: agrupaci¢n de haces A final circuit group and all the high usage circuit groups which have at least one traffic relation for which the final circuit group is in the last choice route. PAGE8 Fascicle II.3 - Rec. E.600 5.28 equivalent random traffic F: trafic equivalent S: tr fico aleatorio equivalente The theoretical poisson traffic that, when offered to a theoretical circuit group (equivalent random circuit group) produces an overflow traffic with a mean and variance equal to that of a given offered traffic. Note - The equivalent random traffic and circuit group represent the traffic impact of a more complex arrangement of offered traffics and high usage circuit groups. ALPHABETICAL INDEX Abandoned call attempt Circuit subgroup 2.9 3.6 Abandoned traffic Communication 5.10 1.1 Alternate route Completed call attempt 5.26 2.11 Alternative route Completion ratio 5.26 2.13 Answer bid ratio Connection 2.15 1.2 Answer seizure ratio Day to busy hour ratio 2.14 5.4 Answer signal delay Delay mode of operation 4.5 1.20 Average daily peak traffic Destination 5.2 5.13 Bid 1.13 Dial tone delay Bidirectional 4.3 3.4 Dialling time Blocked call attempt 2.17 2.8 Effective call attempt Blocked mode of operation 2.11 1.19 Effective traffic Blocked traffic 5.7 5.9 Equivalent random traffic Busy 1.16 5.28 Busy hour 5.1 Erlang Call 2.1 1.12 Call attempt Exchange through connection delay 2.4 4.7 Call congestion External blocking 1.21 4.10 Call demand Final circuit group 2.3 3.9 Call intent First call attempt 2.2 2.5 Call routing First choice circuit group 5.25 3.7 Call string Fully provided circuit group 2.7 3.10 Calling rate Fully routed call attempt 2.16 2.10 Circuit Grade of service 3.1 4.1 Circuit group High usage circuit group 3.5 3.8 Holding time T 1.18 elecommunications traffic Idle 1.15 1.5 Incoming response delay Teletraffic 4.6 1.5 Incoming traffic Terminating traffic 5.19 5.17 Internal blocking Through-connection delay 4.9 4.8 Internal traffic Time consistent busy hour 5.18 5.3 Lost traffic Time congestion 5.10 1.22 Network cluster Traffic carried 5.27 5.5 Observed traffic Traffic distribution imbalance 1.6 5.22 One way Traffic offered 3.3 5.6 Origin 5.12 Traffic matrix Originating traffic 5.15 5.16 Traffic relation Outgoing traffic 5.14 5.20 Traffic routing Overflow traffic 5.24 5.8 Traffic volume Peaked traffic 1.11 1.10 Transit traffic Peakedness factor 5.21 1.8 Trunk circuit Poisson traffic 3.2 1.7 Two way Post dialling delay 3.4 4.4 Unidirectional Pure chance traffic 3.3 1.6 User 1.4 Quality of service Waiting time 4.2 1.23 Queuing time 1.23 Reattempt 2.6 Release 1.17 Repeated call attempt 2.6 Resource 1.3 Route 5.22 Seizure 1.14 Smooth traffic 1.9 Successful call 2.12 Successful call attempt 2.10 Suppressed traffic 5.11 Fascicle II.3 - Rec. 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