1、 ETSI ES 283 039-4 V2.1.1 (2007-04)ETSI Standard Telecommunications and Internet converged Services andProtocols for Advanced Networking (TISPAN);NGN Overload Control Architecture;Part 4: Adaptative Control for the MGCETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 2 Reference DES/TISPAN-03034-4-NGN-R2 Keyw
2、ords control, gateway, MGC ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N 348 623 562 00017 - NAF 742 C Association but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual copies of
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6、uthorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2007. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered for the benefit of its Members. TIPHONTMand t
7、he TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 3 Contents Intellectual Property Rights4 Forewor
8、d.4 1 Scope 5 1.1 Applicability.5 2 References 5 3 Definitions and abbreviations.6 3.1 Definitions6 3.2 Abbreviations .6 4 AGW MGC overload control mechanism.6 4.1 AGW-MGC overload scenarios .6 4.2 AGW-MGC overload control mechanism7 5 H.248 package details.7 5.1 ETSI Notification Rate Package.7 5.1
9、.1 Properties 8 5.1.1.1 Notification Rate .8 5.1.1.2 Off-Hook Notification.8 5.1.2 Events .8 5.1.3 Signals 9 5.1.4 Statistics9 5.1.5 Error codes9 5.1.6 Procedures.9 5.1.7 Detailed overload control behaviour.9 5.1.7.1 Control structure .9 5.1.7.1.1 Introduction .9 5.1.7.1.2 Control adaptor10 5.1.7.1.
10、3 Distribution function .11 5.1.7.1.4 Restriction .11 5.1.7.2 Actions at an overloaded MGC.11 5.1.7.3 Actions at an AGW .13 5.1.7.3.1 Activation and deactivation of AGW regulation mechanism 13 5.1.7.3.2 AGW behaviour when regulation is active14 5.1.7.3.3 Receipt of H.248 signalling on a termination
11、during regulating mechanism 15 5.1.7.4 MGC failure 16 5.1.7.5 AGW failure16 5.1.7.6 AGW re-registration16 6 Management requirements .16 6.1 Configuration management 16 6.1.1 Parameters defined at each AGW .16 6.1.2 Parameters defined at the MGC17 6.2 Performance management 17 6.3 Alarm management 18
12、 History 19 ETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 4 Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and c
13、an be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Purs
14、uant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present doc
15、ument. Foreword This ETSI Standard (ES) has been produced by ETSI Technical Committee Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN). The present document is part 4 of a multi-part deliverable covering the Telecommunications and Internet converged S
16、ervices and Protocols for Advanced Networking (TISPAN); NGN Overload Control Architecture, as identified below: Part 1: “Overview“; Part 2: “Overload and Congestion control; GOCAP“; Part 3: “Overload and Congestion Control for H.248 MG/MGC“; Part 4: “Adaptative Control for the MGC“. ETSI ETSI ES 283
17、 039-4 V2.1.1 (2007-04) 5 1 Scope The present document describes an extension to H.248.1 gateway protocol to enable a robust overload control mechanism to be implemented between Access Media Gateways (AGWs) and their associated Media Gateway Controllers (MGCs). The control is not dependent on the ve
18、rsion of H.248 used. 1.1 Applicability The Rate Based Access Media Gateway/MGC Overload Control Protocol is applicable for: analog line interfaces with Analog Line Signalling (ALS), corresponding AGW H.248 Terminations are of type analog line (ALN); interfaces with Channel Associated Signalling (CAS
19、). The Access Media Gateway/MGC Overload Control Protocol is not applicable for: all interface types with Common Channel Signalling (CCS) for controlling the corresponding bearer connections at the AGW, e.g.: a) ISDN B-channels of ISDN BRIs; b) ISDN B-channels of ISDN PRIs; c) V5.1 B-channels of V5.
20、1 interfaces; d) V5.2 B-channels of V5.2 interfaces; or e) any narrowband Access Node interface with CCS. NOTE 1: CCS traffic is relayed in this kind of AGW by embedded SIGTRAN Signalling Gateways (SG). Such a SG type terminates layer 2 of the control plane protocol stack (e.g. Q.921) and passes the
21、 layer 3 signalling (e.g. Q.931) transparently to the associated MGC. The AGW therefore has no capability to detect start of call events nor provide address digit analysis. NOTE 2: Extending the AGW type (of note 1) by an additional capability of “monitoring layer 3 call control signalling“ may allo
22、w the application of the MGC Overload Control Protocol for CCS interfaces. However, such a concept is for further study. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. References are either specific (ident
23、ified by date of publication and/or edition number or version number) or non-specific. For a specific reference, subsequent revisions do not apply. For a non-specific reference, the latest version applies. Referenced documents which are not found to be publicly available in the expected location mig
24、ht be found at http:/docbox.etsi.org/Reference. NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee their long term validity. 1 ITU-T Recommendation H.248.1: “Gateway control protocol: Version 3“. 2 ITU-T Recommendation Q.543: “Digital excha
25、nge performance design objectives“. ETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 6 3 Definitions and abbreviations 3.1 Definitions For the purposes of the present document, the following terms and definitions apply: call attempt: attempt to setup a path to carry user data between end users Media Gateway
26、Controller overload: point at which the number of call attempts presented to an MGC exceeds its engineered processing capacity for a significant period of time, excluding momentary peaks 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: AGW Access Media G
27、ateway BRI Basic Rate Interface CAS Channel Associated Signalling CCS Common Channel Signalling CPU Central Processor Unit ISDN Integrated Services Digital Network MGC Media Gateway Controller NGN Next Generation Network PRI Primary Rate Interface SNMP Simple Network Management Protocol 4 AGW MGC ov
28、erload control mechanism The purpose of the present document is to define an overload control mechanism between Access Media Gateways (AGWs) and their associated Media Gateway Controllers (MGCs) in an NGN. This mechanism is concerned solely with MGC overload due to excessive originating call attempt
29、s from dependent AGWs. Additional mechanisms (which are outside the scope of the present document) must also be employed to provide an overall overload control solution/strategy in a NGN. 4.1 AGW-MGC overload scenarios In an NGN there exists the possibility that there will be many thousands of AGWs
30、connected to a single MGC. With such an architecture it is envisaged that it may only require a moderate increase in call attempt levels across all of the AGWs to cause a MGC to become overloaded. In the case of media-stimulated events (e.g. tele-voting) or in the event of a disaster, there is often
31、 a large step change in the level of call attempts. In the NGN architecture, such an event is likely to grossly overload the MGCs to a level where service may cease completely. With such large numbers of AGWs connected to a single MGC it will be necessary to efficiently, and quickly, propagate infor
32、mation relating to the MGC overload back to its dependant AGWs, allowing the AGWs to immediately take preventative action, and thus quickly reduce the level of load that is being offered to the overloaded MGC. ETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 7 4.2 AGW-MGC overload control mechanism The high
33、level requirement is to enable the rate of new originating calls that are generated by an AGW to be reduced during conditions of MGC overload, whilst at the same time permitting priority calls to be admitted (e.g. calls to an emergency operator or calls originating from a priority analogue line). Th
34、e basic premise of the load control mechanism is that the MGC is able to invoke a regulating capability on the AGW when the MGC is in overload. This is achieved by sending a H.248 MODIFY command request against the ROOT termination with a new package (see clause 5.1) that is recognized by the AGW as
35、 being indicative of MGC overload, and contains an indication of the amount of load to be regulated by the AGW. Since the AGW is unaware of the concept of a “call“, it is proposed that the AGW shall regulate the level of new off-hook notifications it offers to the overloaded MGC to the level that ha
36、s been signalled by the MGC. A new off-hook is identified at the AGW via detection of an off-hook event at a termination that is in the NULL context. The proposed mechanism enables the MGC to quickly propagate information relating to its overload, and the allowed admitted rate of off-hooks that its
37、dependant AGWs should be regulating in order to reduce the offered load to the MGC. The purpose of the control mechanism is to maintain high effective throughput at an overloaded MGC subject to bounding MGC response times , i.e. keeping the response times short enough to prevent customer reattempts.
38、 The new package would be used by the MGC on the occurrence of either a new originating / terminating a call from/to a dependent AGW to enable regulation of new off-hook notifications. Under this proposal, AGWs will, during a MGC overload, regulate any new Off Hook notifications based upon the curre
39、nt level signalled from the MGC and the priority allocated to the Off Hook. Off Hook notifications that are accepted by the regulation mechanism are passed onto the MGC and handled normally. For those calls that are regulated by the filtering mechanism, then the AGW must first determine if the line
40、is initiating a call to a priority destination. The AGW does this by autonomously responding to the Off Hook notification by applying standard dial tone and then, if necessary, collecting and comparing signalled digits with pre-defined simple digit strings. The signalled digits will be sufficient to
41、 enable the AGW to establish the priority of the call destination. The priority of the call attempt is reassessed using the digit information, and re-presented to the regulation mechanism. If the call is “rejected“ by the regulation mechanism then the AGW applies an autonomous line/port control func
42、tionality defined by a pre-configured script/data. In essence, this script defines a sequence of signals that are applied to the line so that the expected behaviour of the calling party is to hang up and re-attempt the o/g call at a later time. The sequence of signals covers the playing of appropria
43、te indications (e.g. network busy tone) together with appropriate line feeds to eventually return the line to an idle state. 5 H.248 package details A new package is introduced to convey the degree of overload at the (overloaded) MGC to the dependent AGWs. This package is based upon the notification
44、 behaviour (nb) package that has been defined in 1 (H.248.1 version 3, annex E.15). The main differences are that this package implements a rate based restriction and may be applied to AGWs that support any version of H.248. 5.1 ETSI Notification Rate Package Package Name: ETSI Notification Rate Pac
45、kage. PackageID: etsi_nr (0x00a5) Version: 1 Description: This package enables the MGC to convey an allowed maximum admitted rate of off-hooks to the AGW. Extends: None. ETSI ETSI ES 283 039-4 V2.1.1 (2007-04) 8 5.1.1 Properties 5.1.1.1 Notification Rate Property Name: Notification Rate. PropertyID:
46、 notrat (0x0001) Description: This property conveys the maximum allowed admitted rate (per second) of off-hook notifications from terminations in the NULL context that should be regulated by an AGW. The property applies to the ROOT termination. Type: OctetString, with up to 8 octets. Valid strings c
47、onsist of an optional sign character (+, -) followed by 1 to 4 decimal digits, followed by the decimal point “.“ followed by 1 or 2 decimal digits. Examples of valid notrat strings are: “10.0“, “-0.4“, “5.67“ and “-1.0“. Examples of invalid notrat strings are: “-1, 2“ and “1.234E+01“. Possible Value
48、s: A value of 0.0 means that no off-hooks shall be admitted on the AGW. A value 0.0 is the bucket leak rate applied to off-hooks at the AGW. A value of 0.0, received from the MGC, means that leaky bucket restriction shall cease at once. Default Value: -1.0 Defined In: Termination State. Characterist
49、ics: read/write. 5.1.1.2 Off-Hook Notification Property Name: Off-Hook Notification. PropertyID: offHookNot (0x0002) Description: This property determines whether the off-hook event is reported to the MGC for (priority) o/g calls that are regulated and permitted to proceed by the AGW during periods of MGC overload. The property applies to the ROOT termination. Type: Enumeration. Possible Values: “Required“ (x0001) “NotReq“ (x0002 “Required“ means that the off-hook notification shall be reported to the MGC. “NotReq“ means that the off-hook notification sha
