1、ITU-T RECMN*Qm7Lb 93 48b259L 0585851 Tb9 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 Q.716 (03/93) SIGNALLING SYSTEM No.7 - SIGNALLING CONNECTION CONTROL PART (SCCP) PERFORMANCE ITU-T Recommendation Q.716 (Prev
2、iously “CCIlT Recommendation“) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECMN*Q.TLb 93 = 48b2571 0585852 9T5 FOREWORD The Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- m
3、unication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, esta
4、blished the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. -T Recommendation 4.716 was revised by the ITU-T Study Group XI (1988-1993) and was approved by the WTSC (Helsinki, March 1-12, 1993). NOTES 1 As a consequence of a reform process wi
5、thin the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommu
6、nication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms “CCIT”, CCIR or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the
7、proper terminology related to the new structure. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1994 All rights reserved. No part of this publication may be reproduced or u
8、tilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECMN*Q=716 93 M 4862571 0585853 831
9、CONTENTS Page 1 General . 1 2 Definition of performance parameters . 2 3 Specified values for internal parameters 7 4 Influence of new SS No. 7 applications . 9 Recommendation Q.716 (03193) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Serv
10、icesITU-T RECMN*Q.736 93 4862593 0585854 778 Recommendation Q.716 SIGNALLING SYSTEM NO. 7 - SIGNALLING CONNECTION CONTROL PART (SCCP) PERFORMANCE (Melbourne, 1988; modified at Helsinki, 1993) 1 General 1.1 Overview The Signalling Connection Control Part (SCCP) of Signalling System No. 7 (SS No. 7) i
11、s designed as a general message transport system common to the various sub-systems which are using its services. The SCCP is defined in Recommendations 4.7 1 1-4.7 14. SCCP must satisfy the requirements of these various sub-systems and therefore the most stringent sub-system requirements are conside
12、red when defining a value for a performance parameter (most stringent at the time of the specification). To this end, the requirements of the ISDN User Part (ISUP), the OW, and the dialogue between an exchange and a Service Control Point (using the Transaction Capabilities), in particular, were inve
13、stigated. It is assumed that a SCCP which satisfies the requirements of these users mentioned above will also meet those of future users. SCCP performances are defined by parameters of two kinds: - - quality of service parameters as seen by a user of the SCCP; internal parameters which are not seen
14、by the user but which contribute to a quality of service parameter, for example, the transfer delay in a relay point which contributes to the total transit delay of messages as seen by the user. The definitions of all these parameters are presented in clause 2. Then the values allowed for the intern
15、al parameters are defined in clause 3. Values for the quality of service parameters are given in Recommendation 4.709 which deals with HSRCs. Consideration is also given in clause 4 to longer messages and other factors that could affect the performance of the SCCP. 1.2 Definitions Two concepts must
16、be defined when dealing with SCCP performances: SCCP route and SCCP relation. These concepts are similar to the one defined for the MTP (i.e. signalling route and signalling relation). They are defined as follows: SCCP route: An SCCP route is composed of an ordered list of nodes where the SCCP is us
17、ed (origin, relay(s), destination) for the transfer of SCCP messages from an originating SCCP user to the destination SCCP user. SCCP relation: An SCCP relation is a relation between two SCCP users which allows them to exchange data over it. An SCCP relation can consist of one or several SCCP routes
18、. Five types of nodes where SCCP functions are involved are defined as follows: originating node: Origin of a UDT message or of a signalling connection. destination node: Destination of a UDT message or of a signalling connection. relay point: Signalling point where the translation functions of the
19、SCCP for connectionless classes are implemented. relay point without coupling: Signalling point where the relay functions of the SCCP connection oriented classes, but without the coupling of signalling connection sections function, are implemented. relay point with coupling: Signalling point where t
20、he relay functions of the SCCP connection oriented classes, including the coupling of signalling connection sections function, are implemented. Recommendation Q.716 (03/93) 1 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECMN*Q
21、=7Lb 93 = 486259L 0585855 604 2 Definition of performance parameters Some parameters which are defined in this clause cannot be measured from the outside of a signalling point and therefore no values are attributed to them in clause 3 where only measurable values are given. This is true for some int
22、ernal parameters such as for example the transit time of a CR message for the relay function at a relay point without coupling: this parameter does not include in its definition the time due to the MTP and therefore in clause 3 values are given to the transit time at a relay point which includes bot
23、h the time spent in the SCCP and the MTP. The performance of the SCCP can be adversely affected by long link delays, high error rates and long MSUs. See 4.3iQ.706. In networks containing implementations from a number of different vendors, it may be necessary where a parameter has a send and receive
24、component to specify that parameter on such a basis. This will then ensure that the overall requirement is satisfied. 2.1 Performance parameter definitions for the connectionless classes 2.1.1 Quaiity of service parameters The following parameters define the quality of service as seen by a user of t
25、he connectionless classes of the SCCP: undetected errors: This parameter gives the probability that a UDT message is delivered with user data which is defective. residual error probability: This parameter gives the probability that a UDT message is lost, duplicated or delivered incorrectly by the se
26、t constituted of SCCP and the MTP (called Network Service Part or NSP). An incorrectly delivered UDT message is one in which the user data are delivered in a corrupted condition (see undetected errors above), or the user data are delivered to an incorrect NSAP. For class 1 only, a UDT message is con
27、sidered as incorrectly delivered if it is delivered out of sequence by the NSP. out of sequence probability: This parameter gives the probability that UDT messages are delivered out of sequence to the user by the NSP. NOTE - This parameter is relevant only for class 1. total transit delay of a UDT m
28、essage: This parameter is the elapsed time between a N-UNITDATA request primitive issued by a SCCP user at the originating node and the correponding N-UNITDATA indication primitive issued to the SCCP user at the destination node. This parameter is composed of several internal parameters: - - MTP ove
29、rall transfer time; - - sending time of a UDT message by the SCCP; transit time of a UDT message for the relay function at a relay point; receiving time of a UDT message by the SCCP. Depending on the configuration, the second parameter could appear one or several times and the third parameter could
30、appear zero, one or several times. This is illustrated in Figure 1. A probabilistic approach has to be taken to give values to this parameter, considering the various possible SCCP routes and the existence of queues at several points. unavailability of an SCCP relation: This parameter characterizes
31、the inability for two SCCP users to communicate via the NSP. This parameter is determined by the unavailability of the individual components of an SCCP relation: SCCP at the two endpoints, one or several signalling relations and zero, one or several relay points. This unavailability can be reduced b
32、y the duplication of routes at the SCCP level. 2 Recommendation Q.716 (03/93) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling ServicesITU-T RECHN*Q=7Lb 93 LI862591 0585856 540 T that means: to the correct destination, error-free overall transit
33、 time of DT messages: This parameter is the elapsed time between a N-DATA request primitive and the corresponding N-DATA indication primitive. This parameter is composed of several internal parameters: - sending time of a DT message by the SCCP; - MTP overall transfer time; - - transit time of a DT
34、message for the relay function at a relay point with coupling; receiving time of a DT message by the SCCP. Depending of the configuration of the signalling connection, the second parameter could appear one or several times and the third parameter could appear zero, one or several times (see Figure 1
35、). A probabilistic approach has to be taken to give values to this parameter, considering the various possible SCCP routes and the existence of queues at several points. undetected errors: This parameter gives the probability that a DT message is delivered with user data which is defective. residual
36、 error rate for DT messages: This parameter gives the probability that a DT message is lost, duplicated, missequenced or incorrectly delivered by the NSP. A DT message is incorrectly delivered if user data is delivered in a corrupted condition (see undetected errors above), or the user data are deli
37、vered to an incorrect NSAP. out of sequence probability for DT messages: This parameter gives the probability that DT messages are delivered out of sequence to the user by the NSP. signalling connection unsolicited reset and premature release probability: This parameter gives the probability that a
38、connection release or reinitialization due to the SCCP occurs on a signalling connection during a given time. The unavailability of an SCCP relation is an internal parameter to be considered when calculating the probability of a connection release occurrence due to the SCCP. signalling connection re
39、set delay: This parameter is the elapsed time between a N-RESET request primitive and the corresponding N-RESET confirmation primitive for a successful signalling connection reset. 4 Recommendation Q.716 (03/93) COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Infor
40、mation Handling Services ITU-T RECMN*Qm71b 93 = 48b2591 0585858 313 2.2.2 Internai parameters The following parameters are internai to the network service but they contribute to the quality of service as components of a parameter of the previous section for connection oriented classes of the SCCP. S
41、CCP component of the signalling connection establishment time: This parameter is composed of two times: - the elapsed time between a N-CONNECT request primitive at the origin node and the corresponding N-CONNECT indication primitive at the destination node; - the elapsed time between a N-CONNECT res
42、ponse primitive at the destination node and the corresponding N-CONNECT confirmation primitive at the origin node. It is composed of several internal parameters: - sending time of a CR message by the SCCP; - MTP overall transfer time; - transit time of a CR message for the relay function at a relay
43、point without coupling; - transit time of a CR message for the relay function at a relay point with coupling; - receiving time of a CR message by the SCCP; - sending time of a CC message by the SCCP; - transit time of a CC message for the relay function at a relay point with coupling; - receiving ti
44、me of a CC message by the SCCP. Depending on the configuration these parameters can appear zero, one or several times. A probabilistic approach has to be taken to give values to this parameter, considering the various possible configurations and the existence of queues at several points. sending tim
45、e of a CR message by the SCCP: This parameter is the elapsed time between the N-CONNECT request primitive and the corresponding MTP-TRANSFER request primitive (for the transfer of the CR message). NOTE - The value of this parameter may differ substantially depending wether or not a translation funct
46、ion is used in the SCCP. MTP overall transfer time: This parameter is already defined in 4.3.314.706. transit time of a CR message for the relay function at a relay point without coupling: This parameter is the elapsed time between a MTP-TRANSFER indication primitive corresponding to an incoming CR
47、message at a relay point without coupling, and the associated MTP-TRANSFER request primitive corresponding to the outgoing CR message. transit time of a CR message for the relay function at a relay point with coupling: This parameter is the elapsed time between a MTP-TRANSFER indication primitive co
48、rresponding to an incoming CR message at a relay point with coupling, and the associated MTP-TRANSFER request primitive corresponding to the outgoing CR message (which may differ from the incoming one only by the called party address). receiving time of a CR message by the SCCP: This parameter is th
49、e elapsed time between a MTP-TRANSFER indication primitive (for an incoming CR message), an8 the corresponding N-CONNECT indication primitive. sending time of a CC message by the SCCP: This parameter is the elapsed time between a N-CONNECT respose primitive and the corresponding MTP-TRANSFER request primitive (for the transfer of the CC message). Recommendation Q.716 (03/93) 5 COPYRIGHT International Telecommunications Union/ITU TelecommunicationsLicensed by Information Handling Services ITU-T RECflN*Q-7Lb 93 m LIBb259L 0585859 25T Undected errors transit time of a CC message
