1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0300218.2013 INTEGRATED SERVICES DIGITAL NETWORK (ISDN) MANAGEMENT DATA-LINK NETWORK LAYERS As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing
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5、 information, visit . AMERICAN NATIONAL STANDARD Approval of an American National Standard requires review by ANSI that the requirements for due process, consensus, and other criteria for approval have been met by the standards developer. Consensus is established when, in the judgment of the ANSI Bo
6、ard of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that a concerted effort be m
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8、o the standards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name o
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11、tion of high-protocol abnormality rates and service disruption caused by problems at Layer 2 or Layer 3; Identification of the type of trouble at Layer 2 or Layer 3; and The ability to isolate Layer 2 and Layer 3 troubles. 1.3 Structure Clause 1 describes the scope, purpose, and structure of this do
12、cument. Clause 2 lists the normative references. Clause 3 provides definitions of new terms introduced by this standard. Clauses 4 and 5 describe the data-link-layer and network-layer maintenance capabilities i.e., continuous performance monitoring and protocol capture capabilities. An overview of p
13、rotocol testing is provided in Annex A. A list of acronyms used in this document is provided in Annex B. A bibliography of related standards appears in Annex C. 2 Normative References The following standards contain provisions, which, through reference in this text, constitute provisions of this Ame
14、rican National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indica
15、ted below. ATIS-1000602.1996 (R2009), Integrated Services Digital Network (ISDN) - Data-Link Layer Signaling Specification for Application at the User-Network Interface.1ATIS-1000607.2000 (R2009), Integrated Services Digital Network (ISDN) - Layer 3 Signaling Specification for Circuit Switched Beare
16、r Service for Digital Subscriber Signaling System Number _ 1This document is available from the Alliance for Telecommunications Industry Solutions (ATIS), 1200 G Street N.W., Suite 500, Washington, DC 20005 ATIS-0300218.2013 3 1 (DSS1).2ATIS-1000607.a.2006 (R2011), Supplement to ATIS-1000207.3ATIS-1
17、000608.1991 (R2012), Integrated Services Digital Network (ISDN) - Signaling Specification for X.25 Packet-Switched Bearer Service for Digital Subscriber Signaling System Number 1 (DSS1).4ITU-T Recommendation M.3640, Maintenance: ISDN, 1992.5ITU-T Recommendation Q.921, ISDN user-network interface - D
18、ata link layer specification, 1997.5ITU-T Recommendation Q.921, Amendment 1, ISDN user-network interface - Data link layer specification, Amendment 1, 2000.5ITU-T Recommendation Q.931, ISDN user-network interface layer-3 specification for basic call control, 1998.5ITU-T Recommendation Q.931 Amendmen
19、t 1, ISDN user-network interface layer-3 specification for basic call control, Amendment 1: Extensions for the support of digital multiplexing equipment, 2002.5ITU-T Recommendation X.25, Interface between Data Terminal Equipment (DTE) and Data Circuit- termination Equipment (DCE) for terminals opera
20、ting in the packet mode and connected to the public networks by dedicated circuit, 1996.5ITU-T Recommendation X.25 Corridendum 1, Interface between Data Terminal Equipment (DTE) and Data Circuit- termination Equipment (DCE) for terminals operating in the packet mode and connected to the public netwo
21、rks by dedicated circuit, Corridendum1, 1998.5 3 Definitions 3.1 administration management complex (AMC): A complex controlled by a network provider, which has the responsibility for and capability of (among other management functions) the maintenance functions and the maintenance actions for a netw
22、ork. 3.2 frame: A data-link layer protocol data unit. 3.3 invalid frame: A frame for which one or more of the following conditions apply (in accordance with ATIS-1000602, as appropriate): The frame is not properly bounded by flags. The frame does not consist of an integral number of octets prior to
23、zero-bit insertion or following zero-bit extraction. _ 2This document is available from the Alliance for Telecommunications Industry Solutions (ATIS), 1200 G Street N.W., Suite 500, Washington, DC 20005 3This document is available from the Alliance for Telecommunications Industry Solutions (ATIS), 1
24、200 G Street N.W., Suite 500, Washington, DC 20005 4This document is available from the Alliance for Telecommunications Industry Solutions (ATIS), 1200 G Street N.W., Suite 500, Washington, DC 20005 5This document is available from the International Telecommunications Union. ATIS-0300218.2013 4 The
25、frame contains a frame check sequence error (note that this condition shall not be recorded in the protocol abnormality log). The frame has fewer octets than required (see ATIS-1000602, for details). The frame contains an incorrect address field. 3.4 leaky bucket counter: A counter that is increment
26、ed by one each time an event occurs and is decremented by a fixed value periodically. 3.5 message: A Q.931 network-layer protocol data unit. 3.6 packet: An X.25 network-layer protocol data unit. 3.7 protocol abnormality: A protocol event (protocol errors or other events) indicating that a potential
27、trouble condition exists on the ISDN interface. 3.8 unexpected frame: A valid frame that cannot be processed. The frame itself is perfectly legitimate. Its unexpected character is defined by two conditions: the specific type of frame and the state of the receiver. The Layer 2 protocol states define
28、the proper sequence in which frames are expected to occur. The receiver will compare received frames with its own protocol state to determine whether or not a valid frame is unexpected. Table 1 shows LAPD unexpected frames and Table 2 shows LAPB unexpected frames. There are four protocol states asso
29、ciated with LAPB, and an additional two protocol states associated with LAPD. The six protocol states are explained in the following list: TEI-unassigned state (LAPD only): For a specific Terminal Endpoint Identifier (TEI), the ISDN ET is in the TEI-unassigned state if that TEI has not been assigned
30、 to a Customer Premises Equipment (CPE). TEI-assigned state (LAPD only): The ISDN ET enters the TEI-assigned state once that TEI has been assigned to a CPE. Await-establish state: The ISDN ET enters the await-establish state from the TEI-assigned state once a SABME frame has been sent to the CPE wit
31、h that specific TEI and no response has been received. Multi-frame state: The ISDN ET is in the multi-frame state if the data link has been established i.e., the CPE responds with a UA frame to a SABME sent by the ISDN ET or the ISDN ET sends a UA to respond to a SABME frame received. Multi-frame ti
32、me recovery state: The state of the ISDN ET becomes the multi-frame time recovery state if a frame has been retransmitted and no response has been received. Await-re-establish state: After a SABME has been transmitted to re-establish the data link and no response has been received, the ISDN ET is in
33、 the await-re-establish state. ATIS-0300218.2013 5 Table 1 - LAPD unexpected frames LAPD protocol slate Frames that are unexpected TEI-unassigned UA, DM1, RR, RNR, REJ TEI-assigned UA, I, RR, RNR, REJ Await-Establish I, RR, RNR, REJ Multi-Frame SABME, UA, DM Multi-Frame Time Recovery UA, DM Await-Re
34、-Establish Not Applicable NOTE: DM = Disconnect Mode frame; I = Information frame; REJ = Reject frame; RR = Receiver Not Ready frame; SABME = Set Asynchronous Balanced Mode Extended frame; UA = Unnumbered Acknowledgment frame. Table 2 - LAPB unexpected frames LAPB protocol state Frames that are unex
35、pected Await-Establish I, RR RNR, REJ Multi-Frame SABME, UA, DM Multi-Frame Time Recovery UA, DM Await-Re-Establish Not Applicable NOTE: DM = Disconnect Mode frame; I = Information frame; REJ = Reject frame; RR = Receiver Not Ready frame; SABM = Set Asynchronous Balanced Mode frame; UA = Unnumbered
36、Acknowledgment frame. 4 Required Performance Monitoring Capabilities The data-link-layer and network-layer performance monitoring capabilities include the following: Keeping several counts related to level of performance abnormalities, protocol abnormalities, or both; Keeping data on protocol abnorm
37、alities (e.g., logging of abnormalities); and An on-demand log (capture) of all protocol activity on a given access line (or channel) over a specified time interval. 4.1 Performance Monitoring Parameters The required data-link-layer and network-layer performance monitoring parameters are Layer 2 tra
38、nsmission performance parameters measured by ET; The number of Layer 2 protocol abnormalities detected by ET; and The number of Layer 3 protocol abnormalities detected by ET. ATIS-0300218.2013 6 4.2 Transmission Performance Monitoring Recovery from transmission errors between the ET and the TE is pe
39、rformed by using the error-checking i.e., Frame Check Sequence (FCS) and retransmission capabilities provided by Link Access Procedures on the D-channel (LAPD) and Link Access Procedures Balanced (LAPB). The ET shall keep counts for the D channel LAPD protocol as specified in ITU-T Recommendation M.
40、3640, section 4.1.2. The ET shall keep counts for the following Layer 2 parameters for X.25 packet B-channels of each access line: NOTE: M.3640 specifies these same counts for the D channel. The number of frames with FCS errors detected at the ET; The total number of frames received at the ET; The n
41、umber of frames retransmitted by the ET; and The total number of frames transmitted by the ET. The first two parameters provide an indication of Layer 1 transmission performance for the incoming direction to the ET. The last two parameters provide an approximate indication of Layer 1 transmission pe
42、rformance for the outgoing direction from the ET. The register counts for these parameters shall be readable and resettable on demand. In addition, the ET shall automatically reset the counts at the end of each day. The ET shall also be capable of automatically reporting daily counts for all D-chann
43、els and X.25 packet B-channels whose errored frame counts, retransmission counts, or both, reach or exceed a threshold value. The threshold value shall be a settable ET-based parameter. The default threshold value is for further study. 4.3 Protocol Abnormality Log (Network) The ET shall provide a co
44、mmon log to record protocol abnormalities for all of its access lines. The protocol abnormality log records individual Layer 2 and Layer 3 abnormalities. The log is used to help identify specific Layer 2 and Layer 3 trouble causes. In alignment with M.3640, the protocol abnormality log should be cap
45、able of storing log entries for at least 24 hours under normal operation. New log entries shall, if necessary, replace the oldest entries on a first-in-first-out basis i.e., the most recent data shall always be available. To prevent high rates of abnormalities from flooding the log, the ability to i
46、nhibit entries caused by specific abnormality types and entries caused by specific access lines shall be provided. The ET shall provide an indication when the oldest entry in the log is less than n hours old. The value of n shall be settable within the ET. The procedure for the customer to access th
47、e protocol abnormality log is for further study. 4.3.1 Characteristics of Log Entries All entries into the protocol abnormality log shall contain the following information: Date and time of abnormality; ATIS-0300218.2013 7 Location information (e.g., access line, channel, terminal, etc.); The specif
48、ic condition that occurred (e.g., type of frame/message/packet transmitted or received); The specific cause for that condition (e.g., message cause code); and The reason for any action taken by the ET (e.g., threshold crossing caused service disruption). Whenever the messages/packets contain diagnos
49、tic codes (in addition to cause codes), the diagnostic information shall also be included as part of the log entry. It is acceptable to monitor some abnormalities by either using a log or counter (as explained in the following subclauses). When specific abnormalities are counted (as opposed to logged), thresholding shall be provided. Abnormality counts and thresholds shall be on a daily basis. It will be acceptable to update and threshold the daily counts as infrequently as once an hour. 4.3.2 Layer 2 Proto
