1、 International Telecommunication Union ITU-T G.9905TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2013) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks In premises networks Centralized metric-based source routing Recommendation ITU-T G.9905 ITU-T G-SERIES
2、RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL 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 MET
3、ALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL 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.69
4、9 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA 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.7
5、000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 Metallic access networks G.9700G.9799 Optical line systems for local and access networks G.9800G.9899 In premises networks G.9900G.9999For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T
6、G.9905 (08/2013) i Recommendation ITU-T G.9905 Centralized metric-based source routing Summary Recommendation ITU-T G.9905 specifies centralized metric based source routing (CMSR), a proactive, layer 2 multi-hop routing protocol. CMSR is a proactive routing protocol which can find and maintain relia
7、ble routes considering the link quality of both directions. The routing control packet overhead of CMSR is quite low compared to existing proactive routing protocols such as optimized link state routing (OLSR), so that it can be applied for large-scale networks even on narrow band power line communi
8、cation (PLC) networks. History Edition Recommendation Approval Study Group Unique ID*1.0 ITU-T G.9905 2013-08-29 15 11.1002/1000/12007-en _ *To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For examp
9、le, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.9905 (08/2013) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardiz
10、ation 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. The World Telecommunication Standardization Assembly (WTSA), which m
11、eets 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 1. In some areas of information technology which fall within ITU-T
12、s 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 recognized operating agency. Compliance with this Recommendation i
13、s 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. The words “shall“ or some other obligatory language such as “must“
14、 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 that the practice or implementation of this Recommendation may
15、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 Recommendation development process. As of the date of approval of this
16、Recommendation, ITU had 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 and are therefore strongly urged to consult the TSB patent database a
17、t http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.9905 (08/2013) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewh
18、ere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 Protocol overview . 2 5.1 Outline of operation 2 5.2 Table overview . 5 5.3 Signalling overview 6 5.4 Protocol parameters 7 6 Table and information base 7 6.1 Neighbour table 7 6.2 Route table 8 7 Message format . 8
19、7.1 CMSR source route header . 9 7.2 CMSR message 9 8 Procedure 14 8.1 Hello message exchange . 14 8.2 Topology report message transmission 18 8.3 Route Error message transmission . 19 8.4 Link break determination . 19 8.5 Route break determination . 19 9 Packet transmission 19 9.1 Unicast packet 19
20、 9.2 Broadcast/multicast packet . 20 10 Configuration parameters . 20 Annex A Routing procedure for ITU-T G.9903 . 21 A.1 Defining parameter . 21 A.2 Mesh routing . 21 A.3 Transmission of IPv6 packet triggered by ADPD-DATA primitive 23 A.4 Packet transmission and reception triggered by non-default r
21、outing entity . 24 A.5 Interface between the ITU-T G.9903 adaptation layer and ITU-T G.9905 24 Rec. ITU-T G.9905 (08/2013) 1 Recommendation ITU-T G.9905 Centralized metric-based source routing 1 Scope This Recommendation specifies centralized metric based source routing (CMSR), a proactive, layer 2
22、multi-hop routing protocol. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other refer
23、ences are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference
24、to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.9903 Recommendation ITU-T G.9903 (2014), Narrowband orthogonal frequency division multiplexing power line communication transceivers for G3-PLC networks. IETF RFC 4944 IETF R
25、FC 4944 (2007), Transmission of IPv6 Packets over IEEE 802.15.4 Networks. IETF RFC 6282 IETF RFC 6282 (2011), Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based Networks. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommendation This Recommendation defines
26、the following terms: 3.2.1 1WAY link: A link between neighbour nodes for which only the incoming link cost is available. 3.2.2 2WAY link: A link between neighbour nodes for which both incoming and outgoing link costs are available. 3.2.3 Hello message: A message transmitted by each node in order bot
27、h to notify its existence and to exchange link cost and route information with neighbour nodes. 3.2.4 LC incoming: The cost of a one-way link from a neighbour node. 3.2.5 LC outgoing: The cost of a one-way link toward a neighbour node. 3.2.6 link: A link between two nodes exists if either can receiv
28、e control messages from the other, according to this specification. 3.2.7 link cost (LC): The cost of a link between a pair of nodes, calculated from bidirectional link quality. The LC value used is the greater of “LC incoming“ and “LC outgoing“. 3.2.8 LOST link: A broken link where communication is
29、 no longer possible. 2 Rec. ITU-T G.9905 (08/2013) 3.2.9 node: Communication equipment, including the personal area network (PAN) coordinator, which communicates using the CMSR protocol according to this specification. 3.2.10 provisional route cost: The provisional route quality between a node and t
30、he coordinator, equal to the sum of the route cost from a neighbour node to the coordinator and the LC incoming from the neighbour node. 3.2.11 route cost: The total route quality between a node and the coordinator, equal to the sum of all link costs in the route from the node to the coordinator. 3.
31、2.12 topology report message: A message transmitted to the coordinator (using unicast) that contains route and neighbour node information. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CMSR Centralized Metric based Source Routing LC Link Cost MAC Med
32、ia Access Control NSDU Network Service Data Unit PAN Personal Area Network PLC Power Line Communication 5 Protocol overview Multi-hop routing protocols are a key feature of communication for advanced metering applications over power line communications (PLCs). For a large-scale PLC network, e.g., PL
33、C deployment in a large-scale apartment building, a robust and low overhead routing protocol is required in order to achieve reliable metering. This Recommendation addresses the following main objectives: Perform mesh-under proactive routing on 6LoWPAN in IPv6 networks, and communicate using 16-bit
34、short addresses used by 6LoWPAN. Discover a bidirectional route between a node and a coordinator, taking bidirectional link quality into account. Establish and maintain multiple reliable routes in case route break occurs. Generate control packets which increase as only O(N) for route discovery and m
35、aintenance (with N being the number of nodes present in the network). Deliver data packets with source routing and/or hop-by-hop routing. 5.1 Outline of operation CMSR performs mesh-under routing on 6LoWPAN in IPv6 networks, and communicates using 16-bit short addresses used by 6LoWPAN. In order to
36、perform neighbour node detection and route discovery, a Hello message is used for exchanging route and link quality information between nodes, whereas a topology report message is used to notify the coordinator. The coordinator and nodes maintain neighbour tables for storing information on neighbour
37、 nodes, and route tables for storing route information. Each node determines an optimal route based on the link quality and the number of hops to the coordinator. Rec. ITU-T G.9905 (08/2013) 3 5.1.1 Route discovery Route discovery is carried out with the three steps shown in Figure 5-1. Figure 5-1 O
38、verview of route discovery steps Step 1: Hello message exchange and neighbour table update Each node periodically transmits the Hello message as a 1-hop broadcast message with the interval of HELLO_INTERVAL (or HELLO_INTERVAL_FAST as mentioned in clause 8.1.1). In order to avoid a permanent collisio
39、n of Hello messages, each node randomly shifts the transmission timing. The maximum timing shift is defined by HELLO_JITTER. For route discovery, the node establishes a 2WAY link with the node which already has a route to the coordinator. Figure 5-2 shows how the 2WAY link is established. The node t
40、hat receives the Hello message stores the information included in the Hello message in the neighbour table. When the node receives a Hello message from its neighbour node for the first time, the link between the nodes is considered as a 1WAY link (meaning that the node has measured the LC incoming f
41、rom that neighbour node but does not know the LC outgoing to that neighbour node). The receiving node calculates the provisional route cost as the sum of the route costs in the received Hello messages and the measured LC incoming. The status, LC incoming and provisional route cost are recorded in th
42、e neighbour table (first phase in Figure 5-2). The node selects the neighbour nodes based on the provisional route costs, i.e., neighbour nodes with lowest provisional route costs. Up to LINK_MAX_PREFERRED neighbour nodes may be selected. The node sends a Hello message with the link request (LINK_RE
43、Q sub-message) to the selected neighbour nodes to obtain the LC outgoing. Upon reception of the LINK_REQ sub-message, the neighbour nodes record the LC incoming and LC outgoing according to the received message (second phase in Figure 5-2). The neighbour nodes transmit LINK_REP sub-messages includin
44、g the LC incoming to the originator of the LINK_REQ. The originator node stores the LC incoming in the received LINK_REP sub-message as LC outgoing, and sets the link status as “2WAY“ (third phase in Figure 5-2). Note that the LINK_REQ and LINK_REP sub-messages are transmitted in the Hello message t
45、hat is periodically transmitted with the interval of HELLO_INTERVAL (or HELLO_INTERVAL_FAST). 4 Rec. ITU-T G.9905 (08/2013) G.9905(13)_F5-2 Set Node 2 LC Incomingentry according to linkquality of received HELLO Set Node 2 status entryto 1WAYNode 2HELLO Set Node 1 LC Incoming entryaccording to link q
46、uality of receivedHELLO and LC Outgoing entry toLC value in LINK_REQ Set Node 1 status to 2WAYLINK_REQ:LC Incoming (from Node 2),Addr2Node 2 LINK_REP:LC Incoming (from Node 1),Addr1 Set Node 2 LC Outgoingentry according to value inLINK_REP Set Node 2 status to 2WAYIf Node 1 has received Hello packet
47、s from multiple nodes, Node 1 selectsnodes with lower provisional route cost for LINK_REQ transmission.Phase 1 Phase 2 Phase 3 LINK_UPPERNode 1 Node 1 Node 2 Node 1 HELLOHELLOCoordinatorCoordinatorCoordinatorFigure 5-2 Establishment of 2WAY link using LINK_REQ/LINK_REP sub-messages Step 2: Route det
48、ermination/update The node may receive LINK_REP sub-messages from more than one neighbour node in Step 1. The node calculates the route cost associated with each neighbour node based on the link cost (i.e., greater of LC incoming and LC outgoing) and the route cost information in the LINK_REP sub-me
49、ssage from the neighbour node. The node selects the route with the least route cost. Other routes may be selected as candidates for route recovery. The route information, i.e., relay node addresses and each link cost, is stored in the route table. If the node already has the route to the coordinator and it finds a better route, the route may be updated. Step 3: Topology Report message transmission (route update for the coordinator) The Topology Report me
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