CCAMP WG Osama Aboul-Magd Internet Draft Nortel Networks Document: draft-aboulmagd-ccamp-transport-lmp- Feb. , 2003 00.txt Category: Informational A Transport Network View to LMP Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [1]. This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 except that the right to produce derivative works is not granted. This document is an Internet-Draft and is NOT offered in accordance with Section 10 of RFC2026, and the author does not provide the IETF with any rights other than to publish as an Internet-Draft Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 1. Abstract The Link Management Protocol (LMP) has bee defined at the IETF to facilitate the management of transport network for the sake of supporting IP traffic over transport network. The LMP development has been progressing in the context of GMPLS related work. The LMP was developed with a packet centric view in mind. Since it is intended for the control of transport network it is essential to bridge the gap between the two views. It is the objective of this draft to project LMP in a transport network context and to relate it to the discovery work that has been going on at the ITU. 2. Conventions used in this document Aboul-Magd Informational- Sept. 2003 1 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [2]. 3. Transport Network Architecture Traditionally the development of transport network standards, e.g. SONET, SDH, OTN, etc. have been progressing at T1X1 and at the ITU-T SG 15. To facilitate the development of those standards the ITU have developed network architecture in recommendation G.805. The G.805 architecture is closely followed by the SG 15 in developing its transport network recommendations. G.805 defines layered network architecture which defines a client- server architecture. The architecture is recursive so that it can be applied at different network layers with one layer acts as the server while the layer above it defines the client. The basic components of the G.805 architecture are ôsubnetworksö and ôlinksö. A subnetwork is defined as a set of ports which are available for the purpose of transferring ôcharacteristic informationö. A link consists of a subset of ports at the edge of one subnetwork (or ôaccess groupö) and is associated with a corresponding subset of ports at the edge of another subset or access group. Two types of connections are defined. Link connection (LC) is a fixed and inflexible while a subnetwork connection (SNC) is flexible and is setup and released using management or control plane. A network connection is then a concatenation of subnetwork and link connections. G.805 defines a set of reference points for the purpose of identification in the management and the control plane. A link or a subnetwork connection is delimited by connection points (CP). A network connection is delimited by a termination connection point (TCP). A link connection in the client layer is represented by a pair of adaptation functions and a trail in the server layer network. A trail represents the transfer of monitored adapted characteristics information of the client layer network between access points (AP). A trail is delimited by two access points, one at each end of the trail. For management plane purpose the G.805 reference points are represented by a set of management objects described in ITU recommendation M.3100. Connection termination points (CTP) and trail termination points (TTP) are the management plane objects for CP and TCP (or AP??) respectively. In the same way as in M.3100, the transport resources in G.805 are identified for the purpose of control plane by entities suitable for Aboul-Magd Informational- Sept. 2003 2 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 connection control. G.8080 introduces the reference architecture for the control plane of the automatic switched optical networks (ASON). G.8080 introduces a set of reference points relevant to the control plane and their relationship to the corresponding points in the transport plane. A Subnetwork point (SNP) is an abstraction that represents an actual or potential underlying CP or an actual and potential TCP. A set of SNPs that are grouped together for the purpose of routing is called SNP pool (SNPP). Similar to LC and SNC, the SNP-SNP relationship may be static and inflexible (this is referred to as SNP link connection) or it can be dynamic and flexible (this is referred to as SNP subnetwork connection). 4. G.8080 Discovery Framework The fundamental characteristics of G.8080 discovery framework is the separation between the control and the transport plane name spaces. The separation between the two name spaces has the advantage that the discovery of each plane can be performed independent from that of the other place. It facilitates the commissioning of the transport plane independent from the control plane. The separation of the name spaces allows control plane names to be completely independent of the method used to distribute transport names G.8080 Amendment 1 defines the discovery agent (DA) as the entity responsible for the discovery in the transport plane. The DS operates in the transport name space only and provides the separation between that space and the control plane names. A local DA is is only aware of the CPs and TCPs that are assigned to him. The DA holds the CP-CP link connection in the transport plane to enable SNP-SNP link connections to be bound to them later. Control plane discovery takes place entirely within the control plane name space (SNPs). Link Resource Manager (LRM) hold the SNP- SNP binding information necessary for the control plane name of the link connection, while termination adaptation performer (TAP) holds the relation between the control plane name (SNP) and the transport plane name (CP) of the resource. 5. Overview of G.7714.1 G.7714.1 describes the methods, procedures, and transport plane mechanisms for discovering layer adjacency for ASON. It includes discovery of the relationship of the link connection end points and verifying their connectivity. It applies to Single Layer in the context of the transport name space. The result of the discovery process is a Link Connection name, which includes a pair of Transport end points + Discovery Agent names. G7714.1 allows both in-service discovery using server layer trail overhead, and out-of- service discovery at the client layer. Aboul-Magd Informational- Sept. 2003 3 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 Information relevant to discovery are the DA ID and the TCP ID. The DA ID is allowed to be either a DA address or a DA name. The DA name can then be resolved to a DA address. The TCP ID contains the identifier for the TCP being discovered. This has only local significance within the scope of the DA. Discovery information is exchanged in the Discovery and Discovery Response message. The discovery response message is sent in response to the Discovery message. It contains both the received and the sent DA ID and ICP ID. Mis-wiring can then be detected if the TCP-ID corresponding to the remote end point of the link connection is not the same in both messages. Once a bi-directional link has been discovered it should be checked against management provided policy to determine if correct TCP-link connection end points have been correctly connected. 6. LMP and G.8080 Discovery The Link Management Protocol (LMP) has bee defined at the IETF to facilitate the management of transport network for discovery and control transport network elements. The LMP development has been progressing in the context of GMPLS related work. LMP was developed with a IP framework in mind. However many transport elements do not support IP natively and as a result the concepts of LMP need to be adapted to the transport world. Since LMP functions are intended for the control of transport network it is essential to relate the concepts and functions between the IP and transport views. It is the objective of this draft to project LMP in a transport network context and to relate it to the discovery work that has been going on at the ITU. LMP consists of four procedures. Those procedures are the control channel maintenance, link property correlation, link connection verification, and fault management. One fundamental difference between LMP and G.8080 discovery frame work is the absence of the explicit separation between transport and control plane names. The part of LMP that is relevant to G.7714.1 is the link connection verification part. In both cases in-band discovery message is used. LMP uses an in-band Test message for this purpose that is used to transmit the local Interface ID to the remote end of the link. TestStatus message is used that copies the received Interface ID and transmits the local Interface ID to the other end of the link. While Interface ID in LMP can be IPv4, IPv6, or unnumbered, the TCP ID in G.7714.1 is a transport layer ID that may or may not use any of those format. Aboul-Magd Informational- Sept. 2003 4 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 LMP procedures that are relevant to G.8080 control plane discovery are control channel maintenance and link property correlation. This feature is used to synchronize the TE Link properties and verify the TE link configuration. Link Property Correlation provides full discovery of all intra and inter layer relationships along a potential connection, requiring that a single connection management application manages multiples layers. One of the problems of this approach is that All connection management applications must understand the engineering constraints of the technology used to implement each layer (e.g. at least four different implementations are supported at the Photonic layer). ItÆs not clear either how the topology information can be shared with other applications or how the network can be partitioned. Control plane discovery is described in G.8080 although no recommendation has been started yet. The Control Discovery process described in G.8080 involves the interactions between the DA, TAP and LRM as follows: SNPs are pre-assigned to SNPPs (which are equivalent to LMP TE-Links). When the association CTP-SNP is received from the TAP, and the CTP-CTP relationship have been found as per G.7714.1, the SNP-SNP relation is discovered as well as their associated SNPP-SNPP relation-ship. This relation is then verified by communicating the end-point LRMs. Specific information that need to be exchanged or particular procedures have not been addressed yet. There is indeed the room to use LMP messages and procedures for this purpose. 1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. 2 Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 10. Acknowledgments The author would like to thank Astrid Luzano and Don Fedyk for their valuable comments. 11. Author's Addresses Osama Aboul-Magd Nortel Networks P.O. Box 3511, Station C Aboul-Magd Informational- Sept. 2003 5 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 Ottawa, Ontario, Canada K1Y-4H7 Tel: 613-763-5827 E.mail: osama@nortelnetworks.com Aboul-Magd Informational- Sept. 2003 6 Draft-aboulmagd-ccamp-transport-lmp-00.txt Feb, 2003 Full Copyright Statement "Copyright (C) The Internet Society (date). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Aboul-Magd Informational- Sept. 2003 7