CEPT T CAC 4 E-1990 Monitoring of Network Performance Aspects of Quality of International Packet-Switched Service Using Externally Derived Indicators《监测使用外部衍生指标的国际分组交换业务质量网络性能方面》.pdf
《CEPT T CAC 4 E-1990 Monitoring of Network Performance Aspects of Quality of International Packet-Switched Service Using Externally Derived Indicators《监测使用外部衍生指标的国际分组交换业务质量网络性能方面》.pdf》由会员分享,可在线阅读,更多相关《CEPT T CAC 4 E-1990 Monitoring of Network Performance Aspects of Quality of International Packet-Switched Service Using Externally Derived Indicators《监测使用外部衍生指标的国际分组交换业务质量网络性能方面》.pdf(11页珍藏版)》请在麦多课文档分享上搜索。
1、Recommendation T/CAC 4 (Stockholm 1989 (CAC), revised in Nicosia 1990 (CAC) and Vienna (CAT) Page 1 MONITORING OF NETWORK PERFORMANCE ASPECTS OF QUALITY OF INTERNATIONAL PACKET-SWITCHED SERVICE USING EXTERNALLY DERIVED INDICATORS Recommendation proposed by the project team X.25 Text of the Recommend
2、ation adopted by the “Telecommiinications” Commission: “The European Conference of Posts and Telecommunications Administrations, consideritig that Recommendation T/CAC 2 E on the measurement of packet network performance and quality of service identifies in particular the need to monitor four indica
3、tors, Transmitted throughput WP), Received throughput (RTP), Round-trip delay (RTD) and call set-up delay (CSD), derived from information collected by equipment external to the network, recommends that the procedures to be used by Administrations for monitoring these indicators should be as defined
4、below.” O 1. 1.1. Definitions TRANSMITTED THROUGHPUT (TTP) AND RECEIVED THROUGHPUT (RTP) The Transmitted throughput indicator (TTP) is defined as the average rate of transfer of user data across the calling X.25 interface to the called X.25 interface, expressed in bit/s, under the conditions describ
5、ed below. The Received throughput indicator (RTP) is defined as the average rate of transfer of user data across the calling X.25 interface from the called X.25 interface, expressed in bitfs, under the conditions described below. 1.2. Requirements DTEs are connected at the X.25 interfaces which can
6、be used to generate and receive user data and conform to Annex A (DTE performance, measurement precision, etc.). BothX.25 DTE s should be connected via a standard line interface as used for customer service. They should be located on a switching unit whose characteristics and situation in the networ
7、k in relation to international interfaces are typical of units connecting actual X.25 users on that network. The X.25 DTEs should be connected at 9.6 kbit/s and use the following port configuration parameters: - frame level window of 7; - default packet level window size of 2; - default maximum data
8、 packet size of 128 octets; - default throughput class corresponding to 9.6 kbit/s. There should be no inclusion of any user facility in a call request packet. There should be no other traffic on either X.25 interface. All transmitted data packets are full (i.e. contain 128 octets of user data). 1.3
9、. Procedures 1.3.1. Single measurement To make a single measurement of transmitted throughput from an X.25 interface, the DTE makes a call to a drop function in the DTE at the other X.25 interface. To make a single measurement of received throughput from an X.25 interface, the DTE makes a call to a
10、generator function in the DTE at the other X.25 interface. Edition of August 15, 1990 CEPT T/CAC*Y*E B 2326414 0002912 B W TJCAC 4 E Page 2 1.3.2. 1.3.3. 1.3.4. 1.4. 2. 2.1. 2.2. Each measurement should conform to the following : - the measured interval is between 55 and 65 seconds; - the measured i
11、nterval begins not less than 10 seconds after the start of transmission, or successful receipt, - the entire period between the call set-up and end of the measurement interval has no premature clear The transmitted throughput is calculated as the number of data packets sent during the measurement in
12、terval, multiplied by 1024 bits per packet and divided by the measurement interval length in seconds. The received throughput is calculated as the number of data packets received during the measurement interval, multiplied by 1024 bits per packet and divided by the measurement interval length in sec
13、onds. Evaluating a daily value To evaluate either the transmitted throughput or the received throughput for a particular day, a series of appropriate individual measurements is made : - one measurement is made during each complete hour of the day; - if a measurement is invalidated by apremature clea
14、r or reset, it should be re-attempted as soon as - if there is any complete hour without a successful measurement, the evaluation for that day is abandoned. The value applicable to the day is calculated as the average of the three worst values of the 24 obtained. Evaluating a monthly value To evalua
15、te either the transmitted throughput or the received throughput for a particular month, a set of five appropriate daily values must be obtained during the month. These five values must each apply to a different day of the week, including only those which are normal working days in the countries of b
16、oth of the X.25 interfaces. The value applicable to the month is calculated as the average of the five daily values obtained. Schedule of evaluation Every year each operator of a public X.25 network should evaluate the transmitted throughput to each other public X.25 network for the month of October
17、. Similarly, the received throughput should be evaluated every year for the month of March. Additional evaluations of both transmitted throughput and received throughput for a month, day or other convenient period may be made at the discretion of the network operator. Preference should be given to l
18、arger trafic streams, and evaluations should in particular be made after any physical or logical network configuration change affecting a trafic stream (for example, the introduction of an extra X.75 link, or the replacement of a transit route by a direct route). Processing Before the end of Novembe
19、r every year, each operator of a public X.25 network will send its results of the transmitted throughput evaluations for October to a body designated by CEPT. Similarly, the results of the received throughput evaluations for March will be sent to the designated body before the end of April. The desi
20、gnated body will compile each complete set of evaluation results it receives to produce a matrix of throughput values. This will show the values obtained for each identifiable traffic stream and will be made freely available for publication. Each network operator should, as soon as possible, inform
21、its appropriate partner operators of the results of any additional evaluations which it has made. of the first data packet of the call; or reset. convenient up to five times; ROUND-TRIP DELAY (RTD) Definition The Round-trip delay indicator (RTD) is defined as the average time interval between the st
22、art of trans- mission of a data packet at a calling X.25 interface and the end of reception of its echo from the called X.25 interface, expressed in milliseconds, under the conditions described below. The Round-trip delay indicator reflects the delay encountered by a user between sending a single da
23、ta packet to a fast host and receiving the first packet in response. Requirements DTEs are connected at the X.25 interfaces which can be used to generate and receive user data and conform to Annex B (DTE performance, measurement precision, etc.). Both X.25 DTEs should be connected via a standard lin
24、e interface as used for customer service. They should be located on a switching unit whose characteristics and situation in the network in relation to international interfaces are typical of units connecting actual X.25 users on that network. O Edition of August 15, 1990 2.3. 2.3.1. 2.3.2. 2.3.3. 2.
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