DiffServ Code Point Research Articles

On the utility of unregulated IP DiffServ Code Point (DSCP) usage by end systems

DiffServ was designed to implement service provider quality of service (QoS) policies, where routers change and react upon the DiffServ Code Point (DSCP) in the IP header. However, nowadays, applications are beginning to directly set the DSCP themselves, in the hope that this will yield a more appropriate service for their respective video, audio and data streams. WebRTC is a prime example of such an application. We present measurements, for both IPv4 and IPv6, of what happens to DSCP values along Internet paths after an end system has set them without any prior agreement between a customer and a service provider. We find that the DSCP is often changed or zeroed along the path, but detrimental effects from using the DSCP are extremely rare; moreover, DSCP values sometimes remain intact (potentially having an effect on traffic) for several AS hops. This positive result motivates an analysis of the potential latency impact from such DSCP usage, for which we present the first measurement results. We find that routers at approximately 3% of more than 100,000 links differentiate between the WebRTC DSCP values (EF, AF42 and CS1) and consistently reduce delay in comparison with probes carrying a zero value (CS0) under congestion. In contrast, routers at around 2% of these links increase the delay by a comparable amount under congestion, uniformly for EF, AF42 and CS1.

Exploring DSCP modification pathologies in the Internet

The differentiated service architecture (DiffServ) provides a means for network devices to classify traffic based on the DiffServ codepoint (DSCP) and to map the traffic to a specific QoS forwarding treatment. Successful use beyond the local network depends on consistent remarking and forwarding of the DSCP value inside and at the boundaries of DiffServ domains. This paper provides the results of a new widescale measurement campaign to examine how the DSCP value is altered as packets travel along a set of Internet paths. This allows us to infer whether a packet is likely to receive an appropriate QoS treatment and to comment the opportunities for more widely deploying DiffServ QoS. Our results identify a set of remarking pathologies, revealing that many deployed routers continue to use the previous semantics of the deprecated Type of Service (ToS) field. We also note that is not common to observe clearing of the bits in the DiffServ field, as previously believed for routers in the core of the Internet, although this varies significantly depending on the type of network studied. Our results are related to recent IETF work that recommends use of specific DSCP values.

A Study of IPv6 Labeling Forwarding Model Supporting DiffServ

A new Label Forwarding model is devised to enhance the fast switching for IPv6 packets requiring service differentiation. The proposed model is intended to provide more effective functions than Multi-Protocol Label switching (MPLS). The proposed model includes two parts: labeling module and capacity management module. In labeling module, the packets with the same DiffServ Code Point (DSCP) value and next-hop address can be combined into an aggregate. The performance of aggregates transmitting can be improved at each switch router by only performing cut-through peering at the label in IPv6 packet. In capacity management module, two techniques-statistical multiplexing and resizing, are applied for switch router to achieve maximum link utilization.

DESIGN AND SIMULATION OF A FUZZY LOGIC BANDWIDTH CONTROLLER FOR USERS CLASSIFICATION AND PRIORITIES ALLOCATIONS

Quality of Services (QoS) is utilized as a mean to provide efficient bandwidth provisioning in enterprises communication networks. Resource allocation and prioritization need to be provided for different types of networking traffic especially for real-time. This measurable service-oriented provisioning can be implemented in many forms. However, the simplest and most scalable approach for Ethernet is the well-known Differentiated Services (Diff-Serv). Congestion at the gateway can occur in Local Area and in Wide Area Networks (LAN/WAN) when the bandwidth is fully used. This paper proposes a method to classify users and prioritizes them to share the network link efficiently using a fuzzy logic based bandwidth controller that gives each user an optimal Diff-Serv Code Point (DSCP). This is done by considering the user’s class, type of application and available bandwidth. The proposed model is tested on a realistic situation using enterprise OPNET software simulation.

Design and Simulation of A Fuzzy Logic Bandwidth Controller for Users Classification and Priorities Allocations

Quality of Services (QoS) is utilized as a mean to provide efficient bandwidth provisioning in enterprises communication networks. Resource allocation and prioritization need to be provided for different types of networking traffic especially for real-time. This measurable service-oriented provisioning can be implemented in many forms. However, the simplest and most scalable approach for Ethernet is the well-known Differentiated Services (Diff-Serv). Congestion at the gateway can occur in Local Area and in Wide Area Networks (LAN/WAN) when the bandwidth is fully used. This paper proposes a method to classify users and prioritizes them to share the network link efficiently using a fuzzy logic based bandwidth controller that gives each user an optimal Diff-Serv Code Point (DSCP). This is done by considering the user’s class, type of application and available bandwidth. The proposed model is tested on a realistic situation using enterprise OPNET software simulation.

EVALUATION OF QOS IN UMTS BACKBONE NETWORK BY USING DIFFERENTIATED SERVICES

A distinguishing feature of the Universal Mobile Telecommunications System (UMTS) is the support of different levels of quality of service (QoS) as required by subscribers and their applications. To provide QoS, the UMTS backbone network needs an efficient QoS mechanism to provide the demanded level of services on UMTS network. We implement a model to investigate end-to-end quality of service (QoS) provisioning approaches for UMTS networks in a DiffServ IP network environment. The effort was put on QoS classes mapping from DiffServ to UMTS, Access Control, buffering and scheduling optimization. The DiffServ Code Point was utilized in the E2E UMTS QoS provisioning to differentiate different types of traffic. We hybridized our work by applying Resource reservation protocol (RSVP) in routers and hosts. The main advantages and drawbacks are discussed. We found that our proposed model (hybridized model (DiffServ/RSVP)) improves the end-to-end delay and end-to-end variation compared with DiffServ model only, and it is superior to DiffServ regarding to throughput, utilization and packet loss ratio. The overall work guarantees the E2E QoS parameters of each service class, especially for real-time applications and improved the bandwidth utilization. Simulation results show that DiffServ can be an effective candidate for UMTS backbone bearer service.