1、 International Telecommunication Union ITU-T G.7715.2/Y.1706.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2007) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Data over Transport Generic aspects Transport network control aspects SERIES Y: GLOBAL INFORMATION INFRASTRUC
2、TURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Operation, administration and maintenance ASON routing architecture and requirements for remote route query ITU-T Recommendation G.7715.2/Y.1706.2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIG
3、ITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF I
4、NTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NE
5、TWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 General G.7000G.7099 Transport network control aspec
6、ts G.7700G.7799 PACKET OVER TRANSPORT ASPECTS G.8000G.8999ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) i ITU-T Recommendation G.7715.2/Y.1706.2 ASON routing architecture and requirements for remote route q
7、uery Summary ITU-T Recommendation G.7715.2/Y.1706.2 describes the ASON routing architecture and requirements for remote route query. Source ITU-T Recommendation G.7715.2/Y.1706.2 was approved on 6 February 2007 by ITU-T Study Group 15 (2005-2008) under the ITU-T Recommendation A.8 procedure. Keyword
8、s ASON, connection controller, control plane, hierarchical routing, remote route query, route query requester, route query responder, routing controller. ii ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the
9、 field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. 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. Th
10、e World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution
11、1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a
12、recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. Th
13、e words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility
14、 that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recomme
15、ndation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information a
16、nd are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2007 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) iii CONTENTS P
17、age 1 Scope 1 2 References. 1 3 Terms and definitions . 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation. 2 4 Abbreviations and acronyms 3 5 Conventions 3 6 General architecture 3 6.1 Route query as used by RC federations 3 6.2 Route query interface . 5 6.3 Path computation b
18、y a single or multiple RCs . 6 6.4 Hierarchical relationship between communicating RCs 7 6.5 Discovery of a route query responder 8 6.6 Capability of a route query responder 8 6.7 Route request and response messages 8 6.8 Routing controllers and their adjacency. 9 6.9 Communication channels for rout
19、e query messages 9 7 Requirements 9 7.1 Architectural requirements . 9 7.2 Discovery requirements 10 7.3 Protocol requirements. 10 Appendix I Remote route query examples 11 I.1 Step by step remote route query . 11 I.2 Simultaneous remote route query. 13 I.3 Hierarchical remote route query. 15 I.4 Hi
20、erarchical source routing using route query interface 17 ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) 1 ITU-T Recommendation G.7715.2/Y.1706.2 ASON routing architecture and requirements for remote route query 1 Scope This Recommendation specifies the requirements and architecture for the functions perform
21、ed by routing controllers (RC) during the operation of remote route query. The purpose of the remote route query is to compute one or more routing paths for a switched connection (SC) or a soft permanent connection (SPC) within the framework of the automatically switched optical network (ASON). Duri
22、ng the operation of remote route query, a RC (route query requester) sends a RI_QUERY message to another RC (route query responder) not associated with the same set of layer resources, and if a routing path (or more) is found after computation, the route query responder would send back a RI_UPDATE m
23、essage to the route query requester. A routing path for a SC or SPC may be computed collaboratively by a group of RCs in this manner. The route query interface as defined by ITU-T G.8080 is used by routing controllers when they communicate with each other during the remote route query operation. Not
24、e that the route query interface is used in two different cases. First, a connection controller (CC) might request its routing controller for a routing path, and secondly, a routing controller (RC-X) might send a request to another routing controller (RC-Y) for a routing path, either because it (RC-
25、X) needs to respond to a connection controller (CC-X) or a remote routing controller (RC-A), for a route query. The second case, i.e., the RC-to-RC communication for path computation, is the main focus of this Recommendation. The messages exchanged between routing controllers during the remote route
26、 query operation fall into the same category of the routing messages as defined in ITU-T G.7715, and they are transported over a data communication network (DCN). This Recommendation takes a protocol neutral approach, i.e., it does not specify any protocol solution for the communication between rout
27、ing controllers during remote route query operation. The routing algorithm used by a route query responder during the path computation is beyond the scope of this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this
28、 text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent editi
29、on of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.7712 ITU-T Recommendati
30、on G.7712/Y.1703 (2003), Architecture and specification of data communication network. ITU-T G.7713 ITU-T Recommendation G.7713/Y.1704 (2006), Distributed call and connection management (DCM). ITU-T G.7713.1 ITU-T Recommendation G.7713.1/Y.1704.1 (2003), Distributed call and connection management (D
31、CM) based on PNNI. ITU-T G.7713.2 ITU-T Recommendation G.7713.2/Y.1704.2 (2003), Distributed call and connection management: Signalling mechanism using GMPLS RSVP-TE. 2 ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) ITU-T G.7713.3 ITU-T Recommendation G.7713.3/Y.1704.3 (2003), Distributed call and connectio
32、n management: Signalling mechanism using GMPLS CR-LDP. ITU-T G.7715 ITU-T Recommendation G.7715/Y.1706 (2002), Architecture and requirements for routing in the automatically switched optical networks plus Amendment 1 (2007). ITU-T G.7715.1 ITU-T Recommendation G.7715.1/Y.1706.1 (2004), ASON routing
33、architecture and requirements for link state protocols. ITU-T G.8080 ITU-T Recommendation G.8080/Y.1304 (2006), Architecture for the automatically switched optical network (ASON). ITU-T G.8081 ITU-T Recommendation G.8081/Y.1353 (2004), Terms and definitions for automatically switched optical network
34、s (ASON). 3 Terms and definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 data communication network (DCN): ITU-T G.7712 3.1.2 connection controller (CC): ITU-T G.8080 3.1.3 federation: ITU-T G.8080 3.1.4 protocol controller (PC): ITU-T G.808
35、0 3.1.5 routing area (RA): ITU-T G.8080 3.1.6 routing controller (RC): ITU-T G.8080 3.1.7 routing information database (RDB): ITU-T G.8081 3.1.8 soft permanent connection (SPC): ITU-T G.8080 3.1.9 switched connection (SC): ITU-T G.8080 3.1.10 routing adjacency (RAdj): ITU-T G.7715 3.2 Terms defined
36、in this Recommendation This Recommendation defines the following terms: 3.2.1 remote route query: An operation where a routing controller communicates with another routing controller, which does not have the same set of layer resources, in order to compute a routing path in a collaborative manner. 3
37、.2.2 route query requester: A connection controller or routing controller that sends a route query message to a routing controller requesting for one or more routing path that satisfies a set of routing constraints. 3.2.3 route query responder: A routing controller that performs path computation upo
38、n reception of a route query message from a routing controller or connection controller, sending a response back at the end of computation. ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) 3 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ASON Automatically Swit
39、ched Optical Network CC Connection Controller DCN Data Communication Network E-NNI External Network-Network Interface NE Network Element NNI Network-to-Network Interface RC Routing Controller SC Switched Connection SPC Switched Permanent Connection 5 Conventions None 6 General architecture The remot
40、e route query operation is part of ASON routing paradigms as defined in ITU-T G.8080, where when one routing controller does not have sufficient routing information in a local RDB to compute a routing path for a connection request, it may communicate with another routing controller at a remote site
41、for assistance. 6.1 Route query as used by RC federations As described in ITU-T G.8080, a routing controller can be implemented as a distributed set of entities that make up a cooperative federation, i.e., RC federations. There are two aspects of the use of the RC federations, as follows: 1) Routing
42、 topology information may be exchanged between RC federations and also among RCs within a single federation. This aspect is described in ITU-T G.7715 and ITU-T G.7715.1. 2) Route query messages may be exchanged between RC federations and also among RCs within a single federation. This aspect is desc
43、ribed in this Recommendation. Note that these two aspects are associated with different functions performed by routing controllers. There are different styles that are used by RC federations during remote route query operation including the following: 1) step-by-step remote path computation; 2) hier
44、archical remote path computation; 3) combination of the above two. The step-by-step case is illustrated in Figure 1, where the dotted lines show the RC federation boundaries. Each RC is responsible to compute a portion of the end-to-end routing path, usually within its own routing area; for the port
45、ion of the routing path that is outside of its routing area, the RC would first decide the next RC in the chain that belongs to another routing area. This presumes that the RC has enough knowledge to determine the appropriate next RC or, if not, it has to communicate (simultaneously or successively)
46、 to all neighbouring RCs belonging to another routing area to find out the appropriate one. The RC communicates with that RC belonging to 4 ITU-T Rec. G.7715.2/Y.1706.2 (02/2007) another routing area for assistance in order to compute the remaining routing path. The complete routing path for an end-
47、to-end connection is therefore collaboratively computed by a series of RCs in a step-by-step fashion. G.7715.2/Y.1706.2(07)_F01RCRC RCFigure 1 Step-by-step remote path computation The hierarchical case is illustrated in Figure 2, where the dotted lines show the RC federation boundaries. Each child R
48、C computes routing paths that are within its own routing area. For routing paths that cross routing area boundaries, a child RC invokes remote route query function by communicating with one or more of its parent RC, which resides at the next higher level of the ASON routing hierarchy. In this case,
49、the child RC and a parent RC function as a route query requester and a route query responder, respectively. A parent RC may further communicate with other child RCs that belong to other child routing areas at the next lower hierarchical level, functioning as pairs of route query requester and route query responder, respectively. Note this interaction between child RCs and parent RCs may be recursively performed allowing a routing path to be computed across multiple routing areas. G.7715.2/Y.1706.2(07)_F02RCRCR
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