A survey of internet QoS signaling <s> EH EH <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> EH EH <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> EH EH <s> The flexibility and the wide deployment of IP technologies have driven the development of IP-based solutions for wireless networks, like IP-based Radio Access Networks (RAN). These networks have different characteristics when compared to traditional IP networks, imposing very strict requirements on Quality of Service (QoS) solutions, such as fast dynamic resource reservation, simplicity, scalability, low cost, severe congestion handling and easy implementation. A new QoS framework, called Resource Management in Differentiated Services (RMD), aims to satisfy these requirements. RMD has been introduced in recent publications. It extends the IETF Differentiated Services (Diffserv) architecture with new admission control and resource reservation concepts in a scalable way. This paper gives an overview of the RMD functionality and its performance behavior. Furthermore, it shows that the mean processing delay of RMD signaling reservation messages is more than 1330 times smaller then the mean processing delay of RSVP signaling reservation messages. <s> BIB003
Another framework designed for edge-to-edge dynamic resource allocation inside a DiffServ domain is the Resource Management in DiffServ (RMD) framework BIB003 . The RMD framework specifies the Per Domain Reservation (PDR) and Per Hop Reservation (PHR) protocols that are both triggered at the ingress DiffServ edge router by the end-to-end interdomain QoS protocol (e.g. RSVP). At DiffServ edge routers the inter-domain protocol QoS parameters are mapped to the DiffServ DSCP. The PDR protocol operates edge-to-edge within the DiffServ domain and establishes dynamic per-flow states at the edge routers, enabling per-flow admission control on behalf of the DiffServ domain. The PDR protocol is only processed by the DiffServ edge nodes. The PHR protocol operates hop-by-hop between interior DiffServ routers and reserves requested resources inside the respective DiffServ QoS levels. DiffServ interior routers store per-QoS level reservation states. PDR messages are usually carried encapsulated inside the PHR messages. The RMD framework message sequence is based on a request-response procedure, where reservation requests are sender-initiated and Acknowledgments are sent back by the receiver. RMD reservation states can be either soft or hard states. A refresh mechanism is used for the soft state maintenance. Simulation results show that the mean processing delay of PHR reservation messages are more than 1300 times smaller than that of the RSVP reservation message BIB003 . This is due to the RMD aggregate state maintenance that significantly reduces the look-up time in the reservation state table, compared to RSVP per-flow state maintenance. A similar effort for offering QoS guarantees inside a DiffServ domain is the DiffRes reservation protocol  . DiffRes uses a combination of end-to-end (or edge-to-edge) and hop-by-hop messages to dynamically perform aggregate reservations inside a DiffServ domain. For each flow, after collecting resource availability information along the route, the sender (or the ingress router) issues a reservation request message that performs the actual resource reservation in the DiffServ routers along the route. Per-flow soft states are stored in the DiffServ edge routers while perQoS level states are installed in the core routers. DiffServ core routers add the requested amount of resources to the respective QoS level. In addition, DiffRes employs a mechanism of hop-byhop Acknowledgments for avoiding duplication of reservations, in case an end-to-end reservation message is lost somewhere along the route. However, this mechanism requires the storage of short-lived per-flow states in DiffServ interior routers (for the time period of the reservation establishment) and a per-hop router Acknowledgment overhead. The RSVP aggregation, RMD, and DiffRes protocols are generally triggered by domain edge routers, and enable dynamic per-flow admission control inside the DiffServ network region, while avoiding per-flow QoS state storage in the signaling-aware DiffServ core routers. The described mechanisms generally follow the soft state approach, i.e., they rely on refresh message exchange for maintenance of stored states. In addition, DiffRes provides a mechanism for avoiding duplication of reservations in case of lost reservation messages, requiring additional storage and processing overhead. A centralized approach to intra-domain signaling is offered by the bandwidth broker (BB) architecture (Fig. 8)  . The BB is a logical domain entity aware of the domain's policies and available resources and charged with two major responsibilities. The first responsibility is to manage network resources on behalf of the domain by setting the parameters of the domain routers; the second responsibility is to manage the inter-domain link resources and signaling to other BBs. More specifically, the BB performs QoS parameter mapping, admission control, and resource management for the domain as a response to the end-to-end inter-domain (inter-BB) QoS signaling protocol. For intra-domain resource allocation, the BB could use custom protocols (e.g., SNMP, LDAP) to directly allocate resources to each domain router  BIB001 , or it can trigger and delegate the allocation of resources to an intradomain resource management protocol (e.g. RSVP) BIB002 . Resource reservation inside BB-based domains can take place either on a per-flow (access domains) or a per-aggregate (core domains) basis. An intra-domain aggregation scheme is also proposed, where aggregate allocations using RSVP take place between all ingress/egress router pairs of a core domain based on aggregate traffic measurements BIB002 . Simulation results show that this aggregation scheme offers preferential treatment to QoS packets without starving the best-effort traffic. n Figure 7 . RSVP aggregation. 