A survey of internet QoS signaling <s> RELATED WORK <s> We present a framework for the emerging Internet quality of service (QoS). All the important components of this framework-integrated services, RSVP, differentiated services, multiprotocol label switching (MPLS), and constraint-based routing-are covered. We describe what integrated services and differentiated services are, how they can be implemented, and the problems they have. We then describe why MPLS and constraint-based routing have been introduced into this framework, how they differ from and relate to each other, and where they fit into the differentiated services architecture. Two likely service architectures are presented, and the end-to-end service deliveries in these two architectures are illustrated. We also compare ATM networks to router networks with differentiated services and MPLS. Putting all these together, we give the readers a grasp of the big picture of the emerging Internet QoS. <s> BIB001 </s> A survey of internet QoS signaling <s> RELATED WORK <s> In this paper we propose a two-tier resource management model for the global Internet. Our solution resembles the current two-tier routing hierarchy and allows individual administrative domains to independently make their own decisions on strategies and protocols to use for internal resource management and QoS support. The aggregate traffic crossing domain borders is served according to relatively stable, long-lived bilateral agreements. End-to-end QoS support is achieved through the concatenation of such bilateral agreements. We describe in detail a realization of this two-tier model, where a bandwidth broker (BB) acts as the resource manager for each administrative domain, neighboring bandwidth brokers communicate with each other to establish inter-domain resource agreements. As an illustrative example in this paper we used a simplified RSVP as an intradomain resource allocation protocol for the aggregate traffic between border routers. Our simulation results show that this two-tier design can provide effective end-to-end QoS support for user applications. <s> BIB002 </s> A survey of internet QoS signaling <s> RELATED WORK <s> This document defines requirements for signaling across different network environments, such as across administrative and/or technology domains. Signaling is mainly considered for Quality of Service (Qos) such as the Resource Reservation Protocol (RSVP). However, in recent years, several other applications of signaling have been defined. For example, signaling for label distribution in Multiprotocol Label Switching (MPLS) or signaling to middleboxes. To achieve wide applicability of the requirements, the starting point is a diverse set of scenarios/use cases concerning various types of networks and application interactions. This document presents the assumptions before listing the requirements. The requirements are grouped according to areas such as architecture and design goals, signaling flows, layering, performance, flexibility, security, and mobility. <s> BIB003 </s> A survey of internet QoS signaling <s> RELATED WORK <s> This specification describes the NSIS Signaling Layer Protocol (NSLP) for signaling QoS reservations in the Internet. It is in accordance with the framework and requirements developed in NSIS. Together with GIST, it provides functionality similar to RSVP and extends it. The QoS NSLP is independent of the underlying QoS specification or architecture and provides support for different reservation models. It is simplified by the elimination of support for multicast flows. This specification explains the overall protocol approach, design decisions made and provides examples. It specifies object, message formats and processing rules. <s> BIB004
As depicted in the previous sections, several QoS standards and proposals have been produced during the last decade. The need to cast a global view on the Internet QoS area has driven various research efforts, each of which is focusing on different QoS aspects. More specifically, a first effort to give a global overview of Internet QoS is presented in BIB001 . The authors in BIB001 focus on the various mechanisms that can be used for offering QoS in the Internet and describe the IntServ/DiffServ architectures, MPLS, traffic engineering, and constrained-based routing. The advantages and drawbacks of each method are discussed, as well as the motives behind the introduction of each method and the relations between them. In addition, a comparison between ATM networks and IP router networks using DiffServ and MPLS is attempted. The RSVP protocol is generally used throughout the article to cover the signaling needs of the described QoS architectures. The two-tier QoS signaling approach for the Internet was first presented in BIB002 , which described a realization of this model based on bandwidth brokers. The focus of this work is on the presentation of intra-domain and inter-domain resource allocation procedures. Moreover, a measurementbased approach for the reservation of aggregate resources between domains is proposed. Apart from RSVP, the authors in BIB002 do not consider the applicability of other QoS protocols for intra-or inter-domain usage. The IETF NSIS group (Next Steps in Signaling) [27] is currently very actively working on the design of a generic signaling protocol managing general-purpose states. Since QoS provision is basically an issue of establishing and maintaining reservation states inside network routers, QoS signaling is considered as a special case of the NSIS generic signaling protocol. NSIS is trying to identify which aspects of the existing QoS protocols could constitute useful elements for the future Internet signaling protocols have. They have released two Internet Drafts that review the current QoS architectures and protocols for the Internet. An analysis of the existing QoS solutions, trying to point out open issues in QoS signaling, is provided in  . The QoS solutions considered are the endto-end usage of RSVP, the IntServ over DiffServ architecture, the static assignment of trunk reservations based on DiffServ, and the Aggregated RSVP. Advantages and disadvantages of each QoS solution are further discussed. In an effort to gain useful lessons for the design of the future generic Internet signaling protocol, the authors in  present a review of some of the major QoS signaling protocols and analyze their features. Special focus is given to the RSVP protocol, which is directly examined for compatibility with the NSIS requirements. The RSVP protocol's characteristics and n n n nTable 2. Basic characteristics of QoS signaling protocols. extensions are studied in detail, including RSVP reliability, performance, security and mobility issues, RSVP usage with MPLS, ATM, GMPLS, as well as mechanisms for refresh reduction and reservation across tunnels. A short description and evaluation is given for other QoS signaling proposals. Useful conclusions are drawn regarding the design of the NSIS generic signaling protocol. NSIS is expected to give valuable input in the Internet signaling area. The group has been very active during the past few years and has already specified the requirements for the generic signaling protocol BIB003 and the requirements for a QoS solution for mobile terminals (using Mobile IP)  . Moreover, the NSIS group has designed a general framework for the NSIS Internet signaling protocol  , where the overall signaling protocol suite is split into a generic lower NSIS transport layer and several upper signaling layers, one for each specific signaling application (e.g., QoS signaling layer). The interactions between the two layers are also described in  . A protocol for the NSIS transport layer that uses the existing IP transport layer protocols has been further proposed  . The NSIS signaling layer protocol for the QoS has been specifically addressed in BIB004 . The NSIS framework supports the multi-tier paradigm addressed in our survey by specifically examining scenarios that include signaling end-to-end, end-to-edge (intra-domain), and edge-to-edge (inter-domain)  . To support this infrastructure within a single signaling framework, NSIS supports local objects that are used only within the boundaries of a domain.