Network Working Group Osama Aboul-Magd Don Fedyk Internet Draft Nortel Networks Document: draft-aboulmagd-ccamp-transport-lmp-02.txt Category: Informational Deborah Brungard AT&T Jonathan Lang Sonos, Inc. Dimitri Papadimitriou Alcatel July 2004 A Transport Network View of LMP Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026 [RFC2026]. By submitting this Internet-Draft, I certify that any applicable patent or other IPR claims of which I am aware have been disclosed, and any of which I become aware will be disclosed, in accordance with RFC3668 [RFC3668]. 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 been developed as part of the Generalized MPLS (GMPLS) protocol suite to manage Traffic Engineering (TE) links. The GMPLS control plane (routing and signaling) uses TE links for establishing Label Switched Paths (LSPs). This memo describes the relationship of the LMP procedures Aboul-magd Expires Jaunary 2005 1 Draft-aboulmagd-transport-lmp-02.txt July 2004 to 'discovery' as defined in the International Telecommunication Union (ITU), and on-going ITU-T work. This document provides an overview of LMP in the context of the ITU-T Automatically Switched Optical Networks (ASON) and transport network terminology and relates it to the ITU-T discovery work to promote a common understanding for progressing the work of IETF and ITU-T. 2. Table of Contents 1. Abstract........................................................1 2. Table of Contents...............................................2 3. Terminology.....................................................2 4. Introduction....................................................3 5. Transport Network Architecture..................................4 5.1 G.8080 Discovery Framework.....................................6 6. Discovery Technologies..........................................8 6.1 Generalized automatic discovery techniques G.7714..............8 6.2 LMP and G.8080 Terminology Mapping.............................8 6.2.1 TE Link Definition and Scope................................10 6.3 LMP and G.8080 Discovery Relationship.........................11 6.4 Comparing LMP and G.8080......................................12 7. Security Considerations........................................13 8. References.....................................................13 8.1 Normative References..........................................13 8.2 Informational References......................................13 9. Acknowledgements...............................................14 10. Author's Addresses............................................14 Full Copyright Statement..........................................16 3. Terminology The reader is assumed to be familiar with the terminology in [LMP] and [LMP-TEST]. The following ITU terminology/abbreviations are used in this document: Characteristic Information: Signal with a specific format, which is transferred on "network connections". The specific formats will be defined in the technology specific Recommendations. For trails the Characteristic Information is the payload plus the overhead. . The information transferred is characteristic of the layer network. Link: a subset of ports at the edge of a subnetwork or access group which are associated with a corresponding subset of ports at the edge of another subnetwork or access group. OTN: Optical transport network PDH: Plesiosynchronous digital hierarchy SDH: Synchronous digital hierarchy. Aboul-magd Expires January 2005 2 Draft-aboulmagd-transport-lmp-02.txt July 2004 Subnetwork: a set of ports which are available for the purpose of routing 'characteristic information'. Subnetwork Connection (SNC): a flexible connection that is setup and released using management or control plane procedures. Link Connection (LC): a transport entity that transfers information between ports across a link. Network Connection (NC): A concatenation of link and subnetwork connections. Connection Termination Point (CTP): A Connection Termination Point (CTP) represents the state of a Connection Point (CP) [M.3100] The CP is a reference point representing the end point of a link connection and represents the North input port of an Adaptation function. Termination Connection Point (TCP): A reference point that represents the output of a Trail Termination source function or the input to a Trail Termination sink function. A network connection represents a transport entity between TCPs. Subnetwork Point (SNP): SNP is an abstraction that represents an actual or potential underlying connection point (CP) or termination connection point (TCP) for the purpose of control plane representation. Subnetwork Point Pool (SNPP): A set of SNP that are grouped together for the purpose of routing. 4. Introduction The GMPLS control plane consists of several building blocks as described in [GMPLS-ARCH]. The building blocks include signaling, routing, and link management for establishing LSPs. For scalability purposes, multiple physical resources can be combined to form a single traffic engineering (TE) link for the purposes of path computation and GMPLS control plane signaling. As manual provisioning and management of these links is impractical in large networks, LMP was specified to manage TE links. Two mandatory management capabilities of LMP are control channel management and TE link property correlation. Additional optional capabilities include verifying physical connectivity and fault management. [LMP] defines the messages and procedures for GMPLS TE link management. [LMP-TEST] defines SONET/SDH specific messages and procedures for link verification. G.8080 Amendment 1 [G.8080] defines control plane discovery as two separate processes, one process occurs within the transport plane space and the other process occurs within the control plane space. Aboul-magd Expires January 2005 3 Draft-aboulmagd-transport-lmp-02.txt July 2004 The ITU-T has developed Recommendation G.7714 'Generalized automatic discovery techniques' [G.7714] defining the functional processes and information exchange related to transport plane discovery aspects: i.e., layer adjacency discovery and physical media adjacency discovery. Specific methods and protocols are not defined in Recommendation G.7714. ITU-T Recommendation G.7714.1 'Protocol for automatic discovery in SDH and OTN networks' [G.7714.1] defines a protocol and procedure for transport plane layer adjacency discovery (e.g. discovering the transport plane layer end point relationships and verifying their connectivity). The ITU-T is currently working to extend discovery to control plane aspects providing detail on a Discovery framework architecture in G.8080 and a new Recommendation on 'Control plane initial establishment, reconfiguration'. 5. Transport Network Architecture A generic functional architecture for transport networks is defined in the International Telecommunications Union (ITU) recommendation [G.805]. This recommendation describes the functional architecture of transport networks in a technology independent way. This architecture forms the basis for a set of technology specific architectural recommendations for transport networks (e.g., SDH, PDH, OTN, etc.) The architecture defined in G.805 is designed using a layered model with a client-server relationship between layers. The architecture is recursive in nature; a network layer is both a server to the client layer above it and a client to the server layer below it. There are two basic building blocks defined in G.805: "subnetworks" and "links". A subnetwork is defined as a set of ports which are available for the purpose of routing "characteristic information". A link consists of a subset of ports at the edge of one subnetwork (or "access group") and is associated with a corresponding subset of ports at the edge of another subnetwork or access group. Two types of connections are defined in G.805: "link connection" (LC) and "subnetwork connection" (SNC). A link connection is a fixed and inflexible connection, while a subnetwork connection is flexible and is setup and released using management or control plane procedures. A network connection is defined as a concatenation of subnetwork and link connections. Figure 1 illustrates link and subnetwork connections. Aboul-magd Expires January 2005 4 Draft-aboulmagd-transport-lmp-02.txt July 2004 (++++++++) (++++++++) ( SNC ) LC ( SNC ) (o)--------(o)----------(o)--------(o) ( ) CP CP ( ) (++++++++) (++++++++) subnetwork subnetwork Figure 1: Subnetwork and Link Connections G.805 defines a set of reference points for the purpose of identification in both the management and the control plane. These identifiers are NOT required to be the same. A link connection 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. Figure 2 shows a network connection and its relationship with link and subnetwork connections. Figure 2 also shows the CP and TCP reference points. |<-------Network Connection---------->| | | | (++++++++) (++++++++) | |( SNC ) LC ( SNC ) | (o)--------(o)----------(o)--------(o)| TCP( )| CP CP |( )TCP (++++++++) | | (++++++++) | | | Trail | |<-------->| | | --- --- \ / \ / - - AP 0 0 AP | | (oo)------(oo) For management plane purposes the G.805 reference points are represented by a set of management objects described in ITU recommendation M.3100 [M.3100]. Connection termination points (CTP) and trail termination points (TTP) are the management plane objects for CP and TCP respectively. Aboul-magd Expires January 2005 5 Draft-aboulmagd-transport-lmp-02.txt July 2004 In the same way as in M.3100, the transport resources in G.805 are identified for the purposes of the control plane by entities suitable for 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 ASON 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 or 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 an SNP link connection) or it can be dynamic and flexible (this is referred to as a SNP subnetwork connection). 5.1 G.8080 Discovery Framework G.8080 provides a reference control plane architecture based on the descriptive use of functional components representing abstract entities and abstract component interfaces. The description is generic and no particular physical partitioning of functions is implied. The input/output information flows associated with the functional components serve for defining the functions of the components and are considered to be conceptual, not physical. Components can be combined in different ways and the description is not intended to limit implementations. Control plane discovery is described in G.8080 by using three components: Discovery Agent (DA), Termination and adaptation performer (TAP), and Link Resource Manager (LRM). The objective of the discovery framework in G.8080 is to establish the relationship between CP-CP link connections (transport plane) and SNP-SNP link connections (control plane). The fundamental characteristics of G.8080 discovery framework is the functional separation between the control and the transport plane discovery processes and name spaces. The separation between the two processes and corresponding two name spaces has the advantage that the discovery of the transport plane can be performed independent from that of the control plane (and vice-versa), and independent of the method used in each name space. This allows assigning link connections in the control plane without the link connection being physically connected. Discovery encompasses two separate processes: (1) transport plane discovery, i.e. CP-to-CP and TCP-to-TCP connectivity and (2) control plane discovery, i.e. SNP-to-SNP and SNPP links. G.8080 Amendment 1 defines the discovery agent (DA) as the entity responsible for discovery in the transport plane. The DA operates in the transport name space only and in cooperation with the Termination and Adaptation performer [TAP], provides the separation Aboul-magd Expires January 2005 6 Draft-aboulmagd-transport-lmp-02.txt July 2004 between that space and the control plane names. A local DA is only aware of the CPs and TCPs that are assigned to it. The DA holds the CP-CP link connection in the transport plane to enable SNP-SNP link connections to be bound to them at a later time by the TAP. The CP- CP relationship may be discovered (e.g. per G.7714.1) or provided by a management system. Control plane discovery takes place entirely within the control plane name space (SNPs). The Link Resource Manager (LRM) holds the SNP-SNP binding information necessary for the control plane name of the link connection, while the termination adaptation performer (TAP) holds the relation between the control plane name (SNP) and the transport plane name (CP) of the resource. Figure 3 shows the relationship and the different entities for transport and control discoveries. LRM LRM +-----+ holds SNP-SNP Relation +-----+ | |-------------------------| | +-----+ +-----+ | | v v +-----+ +-----+ | o | SNP's in SNPP | o | | | | | | o | | o | | | | | | o | | o | +-----+ +-----+ | | v v Control Plane +-----+ +-----+ Discovery | | Termination and | | ---|-----|-------------------------|-----|--------- | | Adaptation Performer | | +-----+ (TAP) +-----+ Transport Plane | \ / | Discovery | \ / | | +-----+ +-----+ | | | DA | | DA | | | | | | | | | +-----+ +-----+ | | / \ | V/ \V O CP (Transport Name) O CP (Transport Name) Figure 3: Discover in the Control and the Transport Planes Aboul-magd Expires January 2005 7 Draft-aboulmagd-transport-lmp-02.txt July 2004 6. Discovery Technologies 6.1 Generalized automatic discovery techniques G.7714 Generalized automatic discovery techniques are described in G.7714 to aid resource management and routing for G.8080. The term routing here is described in the transport context of routing connections in an optical network as opposed to the routing context typically associated in packet networks. G.7714 is concerned with two types of discovery: - Layer adjacency discovery - Physical media adjacency discovery Layer adjacency discovery can be used to correlate physical connections with management configured attributes. Among other features this capability allows reduction in configuration and the detection of miswired equipment. Physical media adjacency discovery is a process that allows the physical testing of the media for the purpose of inventory capacity and verifying the port characteristics of physical media adjacent networks. G.7714 does not specify specific protocols but rather the type of techniques that can be used. G.7714.1 specifies a protocol for layer adjacency with respect to SDH and OTN networks for Layer adjacency Discovery. A GMPLS method for Layer Discovery using elements of LMP are included in this set of procedures. An important point about the G.7714 specification is it specifies a discovery mechanism for optical networks but not necessarily how the information will be used. It is intended that the Transport Management plane or a Transport control plane may subsequently make use of the discovered information. 6.2 LMP and G.8080 Terminology Mapping GMPLS is a set of IP-based protocols, including LMP, providing a control plane for multiple data plane technologies, including optical/transport networks and their resources (i.e. wavelengths, timeslots, etc.) and without assuming any restriction on the control plane architecture (see [GMPLS-ARCH]). Whereas, G.8080 defines a control plane reference architecture for optical/ transport networks and without any restriction on the control plane implementation. Being developed in separate standards forums, and with different scope, they use different terms and definitions. Terminology mapping between LMP and ASON (G.805/G.8080) is an important step towards the understanding of the two architectures Aboul-magd Expires January 2005 8 Draft-aboulmagd-transport-lmp-02.txt July 2004 and allows for potential cooperation in areas where cooperation is possible. To facilitate this mapping, we differentiate between the two types of data links in LMP. According to LMP, a data link may be considered by each node that it terminates on as either a 'port' or a 'component link'. The LMP notions of port and component link are supported by the G.805/G.8080 architecture. G.8080 refers to a component link as a variable adaptation function i.e. a single server layer trail dynamically supporting different multiplexing structures. Note that when the data plane delivers its own addressing space, LMP Interface_IDs and Data Links IDs are used as handles by the control plane to the actual CP Name and CP-to-CP Name, respectively. The terminology mapping is summarized in the following table: +----------------+--------------------+-------------------+ | ASON Terms | GMPLS/LMP Terms | GMPLS/LMP Terms | | | Port | Component Link | +----------------+--------------------+-------------------+ | CP | Interface (Port) | Interface. | | | |(Comp. link) | +----------------+--------------------+-------------------+ | CP Name | Interface ID | Interface ID(s) | | | no further sub- | resources (such as| | | division for(label)| timeslots, etc.) | | | resource allocation| on this interface | | | | are identified by | | | | set of labels | +----------------+--------------------+-------------------+ | CP-to-CP | Data Link | Data Link | +----------------+--------------------+-------------------+ | CP-to-CP Name | Data Link ID | Data Link ID | +----------------+--------------------+-------------------+ | SNP | TE Link (Port) | TE Link (Comp) | | | (single link) | (single link) | +----------------+--------------------+-------------------+ | SNP Name | Link ID | Link ID | +----------------+--------------------+-------------------+ | SNP LC | TE Link | TE Link | +----------------+--------------------+-------------------+ | SNP LC Name | TE Link ID | TE Link ID | +----------------+--------------------+-------------------+ | SNPP | TE Link (Port) | TE Link (Comp) | +----------------+--------------------+-------------------+ | SNPP Name | Link ID | Link ID | +----------------+--------------------+-------------------+ | SNPP Link | TE Link | TE Link | +----------------+--------------------+-------------------+ | SNPP Link Name | TE Link ID | TE Link ID | +----------------+--------------------+-------------------+ where: - Data Link ID: - TE Link ID: Aboul-magd Expires January 2005 9 Draft-aboulmagd-transport-lmp-02.txt July 2004 6.2.1 TE Link Definition and Scope In the table TE link is equated the concept of SNP, SNP LC, SNPP and SNPP link. The definition of the TE link is broad in scope and is useful repeating here. The original definition appears in [GMPLS- RTG]: "A TE link is a logical construct that represents a way to group/map the information about certain physical resources (and their properties) that interconnects LSRs into the information that is used by Constrained SPF for the purpose of path computation, and by GMPLS signaling." While this definition is concise it is probably worth pointing some of the implications of the definition. A TE link is not limited to a single path. TE links can be formed over resources (e.g. individual OC-3c links) which take identical or different physical paths between Nodes. The TE link construct is a logical construction encompassing many layers in networks [RFC 3471]. A TE link can represent either unallocated potential or allocated actual resources. Further allocation is represented by Bandwidth reservation and the resources may be real or in the case of packets virtual to allow for over booking or other form of statistical multiplexing schemes. Since TE links may represent large number of parallel resources they can be bundled for efficient summarization of resource capacity. Typically bundling represents a logical TE link resource at a particular Interface switching capability. Once TE link resources are allocated the actual capacity may be represented as LSP hierarchical (tunneled) TE link capability in another logical TE link [HIER]. TE links also incorporate the notion of a Forwarding Adjacency (FA) and Interface Switching capability [GMPLS-ARCH]. The FA allows transport resources to be represented as TE-links. The interface switching capability specifies the type of transport capability such as Packet switch Capable(PSC), Layer-2 Switch Capable (L2SC), Time- Division Multiplex (TDM), Lambda Switch Capable (LSC) and Fiber- Switch Capable (FSC).. A typical TE link between GMPLS controlled optical nodes would consist of a bundled (TE link) which itself consists of a mix of point-to-point links and FAs [BUNDLE] . A TE link is identified by the tuple: (Bundled link Identifier(32 bit number), Component link Identifier(32 bit number) and generalized label(media specific)). Aboul-magd Expires January 2005 10 Draft-aboulmagd-transport-lmp-02.txt July 2004 6.3 LMP and G.8080 Discovery Relationship LMP currently consists of four primary procedures, of which, the first two are mandatory and the last two are optional: 1. Control channel management 2. Link property correlation 3. Link verification 4. Fault management LMP procedures that are relevant to G.8080 control plane discovery are control channel management, link property correlation and Link Verification.. Key to understanding G.8080 discovery aspects in relation to [LMP] is that LMP procedures are specific for an IP- based control plane abstraction of the transport plane. LMP control channel management is used to establish and maintain control channel connectivity between LMP adjacent nodes. In GMPLS, the control channels between two adjacent nodes are not required to use the same physical medium as the TE links between those nodes. The control channels that are used to exchange the GMPLS control- plane information exist independently of the TE links they manage (i.e., control channels may be in-band or out-of-band, provided the associated control points terminate the LMP packets). The Link Management Protocol [LMP] was designed to manage TE links, independently of the physical medium capabilities of the data links. This is done using a Config message exchange followed by a lightweight keep-alive message exchange. Link property correlation is used to aggregate multiple data links into a single TE Link and to synchronize the link properties. Link verification is used to verify the physical connectivity of the data links and verify the mapping of the Interface-ID to Link-ID (CP to SNP). The local-to-remote associations can be obtained using a priori knowledge or using the Link verification procedure. Fault management is primarily used to suppress alarms and to localize failures. It is an optional LMP procedure, it's use will depend on the specific technology's capabilities. [LMP] supports distinct transport and control plane name spaces with the (out-of-band) TRACE object (see [LMP-TEST]). The LMP TRACE object allows transport plane names to be associated with interface identifiers [LMP-TEST]. Aspects of LMP link verification appear similar to G.7714.1 discovery, however the two procedures are different. G.7714.1 provides discovery of the transport plane layer adjacencies. It Aboul-magd Expires January 2005 11 Draft-aboulmagd-transport-lmp-02.txt July 2004 provides a generic procedure to discover the connectivity of two end points in the transport plane. Whereas, LMP link verification procedure is a control plane driven procedure and assumes either (1) a priori knowledge of the associated data plane's local and remote end point connectivity and Interface_IDs (e.g. via management plane or use of G.7714.1), or (2) support of the remote node for associating the data interface being verified with the content of the TRACE object (inferred mapping). For SONET/SDH transport networks, LMP verification uses the SONET/SDH Trail Trace identifier (see [G.783]). G.7714.1 supports the use of transport plane discovery independent of the platform using the capability. Furthermore G.7714.1 specifies the use of a Discovery Agent could be located in an external system and the need to support the use of text-oriented man-machine language to provide the interface. Therefore, G.7714.1 limits the discovery messages to printable characters defined by [T.50] and requires Base64 encoding for the TCP-ID and DA ID. External name- servers may be used to resolve the G.7714.1 TCP name, allowing the TCP to have an IP, NSAP or any other address format. Whereas, LMP is based on the use of an IP-based control plane, and the LMP interface ID uses IPv4, IPv6, or unnumbered interface IDs. 6.4 Comparing LMP and G.8080 LMP exists to support GMPLS TE link discovery. In section 5.2.1 we elaborated on the definition of the TE link. LMP enables the aspects of TE links to be discovered, and delivered to the control plane, more specifically the routing plane. G.8080 and G.7714 are agnostic to the type of control plane and discovery protocol used. LMP is a valid realization of a control plane discovery process under a G.8080 model. G.7714 specifies transport plane discovery with respect to the transport layer CTPs or TCPs using ASON conventions and naming for the elements of the ASON control plane and the ASON management plane. This discovery supports a centralized management model of configuration as well as a distributed control plane model, in other words discovered items can be reported to the management plane or the control plane. G.7714.1 provides one realization of a transport plane discovery process. Today LMP and G.7714, G7714.1 are defined in different Standards Organizations. They have evolved out of different naming schemes and architectural concepts. Whereas G.7714.1 supports a transport plane layer adjacency connectivity verification which can be used by a control plane or a management plane, LMP is a control plane procedure for managing GMPLS TEs (GMPLSĘs control plane representation of the transport plane connections). Aboul-magd Expires January 2005 12 Draft-aboulmagd-transport-lmp-02.txt July 2004 7. Security Considerations Since this draft is purely descriptive in nature it does not introduce any security issues. G.8080 and G.7714/G.7714.1 provide security as associated with the Data Communications Network on which they are implemented. LMP is specified using IP which provides security mechanisms associated with the IP network on which it is implemented. 8. References 8.1 Normative References [RFC2026] S.Bradner, "The Internet Standards Process -- Revision3", BCP 9, RFC 2026, October 1996. [RFC3668] S. Bradner, "Intellectual Property Rights in IETF Technology", BCP 79, RFC 3668, February 2004. 8.2 Informational References [LMP] J.P.Lang (Editor), "Link Management Protocol," draft- ietf-ccamp-lmp-10.txt, October 2003. [LMP-TEST] J.P.Lang et al., "SONET/SDH Encoding for Link Management Protocol (LMP) Test messages," draft-ietf- draft-ietf-ccamp-lmp-test-sonet-sdh-04.txt, December 2004. [GMPLS-ARCH] Eric Mannie (Editor), "Generalized Multi-protocol Label Switching Architecture," draft-ietf-ccamp-gmpls- architecture-07.txt, May 2003. [RFC 3471] Lou Berger (Editor), "Generalized Multi-Protocol Label Switching (GMPLS)Signaling Functional Description," draft-ietf-ccamp-gmpls-architecture-07.txt, May 2003. [GMPLS-RTG] K. Kompella & Y. Rekhter (editors) "Routing Extensions in Support of Generalized Multi-Protocol Label Switching", draft-ietf-ccamp-gmpls-routing-09.txt, December 2003. [HIER] K. Kompella & Y. Rekhter " LSP Hierarchy with Generalized MPLS TE", draft-ietf-mpls-lsp-hierarchy-08.txt, September 2002 [BUNDLE] K. Kompella, Y. Rekhter, Lou Berger "Link Bundling in MPLS Traffic Engineering", draft-ietf-mpls-bundle-04.txt, July 2002 Aboul-magd Expires January 2005 13 Draft-aboulmagd-transport-lmp-02.txt July 2004 "For information on the availability of ITU Documents, please see http://www.itu.int" [G.783] ITU-T G.783 (2004), Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks. [G.805] ITU-T G.805 (2000), Generic functional architecture of transport networks. [G.7714] ITU-T G.7714/Y.1705 (2001), Generalized automatic discovery techniques. [G.7714.1] ITU-T G.7714.1/Y.1705.1 (2003), Protocol for automatic discovery in SDH and OTN networks. [G.8080] ITU-T G.8080/Y.1304 (2001), Architecture for the automatically switched optical network (ASON). [M.3100] ITU-T M.3100 (1995), Generic Network Information Model [T.50] ITU-T T.50 (1992), International Reference Alphabet 9. Acknowledgements The authors would like to thank Astrid Lozano, John Drake, Adrian Farrel and Stephen Shew for their valuable comments. 10. Author's Addresses Osama Aboul-Magd Nortel Networks P.O. Box 3511, Station 'C' Ottawa, Ontario, Canada K1Y-4H7 Phone: +1 613 763-5827 Email: osama@nortelnetworks.com Don Fedyk Nortel Networks 600 Technology Park Drive Billerica, MA, 01821 Email: dwfedyk@nortelnetworks.com Deborah Brungard AT&T Rm. D1-3C22 200 S. Laurel Ave. Middletown, NJ 07748, USA Email: dbrungard@att.com Aboul-magd Expires January 2005 14 Draft-aboulmagd-transport-lmp-02.txt July 2004 Jonathan P. Lang Sonos, Inc. 506 Chapala Street Santa Barbara, CA 93101 Email : jplang@ieee.org Dimitri Papadimitriou Alcatel Francis Wellesplein, 1 B-2018 Antwerpen, Belgium Phone: +32 3 240-84-91 Email: dimitri.papadimitriou@alcatel.be Aboul-magd Expires January 2005 15 Draft-aboulmagd-transport-lmp-02.txt July 2004 Full Copyright Statement "Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights." "This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Aboul-magd Expires January 2005 16