Stream Reservation Research Articles

Delay-Guaranteeing Admission Control for Time-Sensitive Networking Using the Credit-Based Shaper

With real-time communication being a key part of the fourth industrial revolution, the need for Quality of Service (QoS) in industrial networks is gaining increasing importance. Time-Sensitive Networking (TSN) faces this need, for example, by introducing new scheduling mechanisms. The Credit-Based Shaper (CBS) has been introduced to TSN to offer low delays for multiple traffic classes by applying rate limitations. Currently, flows are reserved decentrally in CBS networks using a Stream Reservation Protocol (SRP). In contrast, the new TSN standard IEEE 802.1Qcc allows for a centralized architecture to favor short reconfiguration latencies. However, no online admission control scheme which offers safe delay bounds has been proposed for this central architecture. To close this gap, we propose two models for admission control in TSN networks using CBS. Both models offer deadline-guaranteeing flow allocation, including routing and prioritization of flows, and configure forwarding devices while eliminating packet loss. Our models utilize the mathematical framework of Network Calculus to calculate worst-case flow delays and buffer sizes. We show how our models allow for more reservations than the decentralized standard approach by improved resource utilization. We validate our models both in synthetic and industrial network scenarios. Additionally, we compare the effects and parameters of our two models, providing guidance on when to choose them.

Simplified Stream Reservation Protocol Over Software-Defined Networks for In-Vehicle Time-Sensitive Networking

As the automotive industry adopts Ethernet for in-vehicle network technology, automotive Ethernet has to handle bounded delay traffic. IEEE std 802.1Q introduces the stream reservation protocol (SRP) to reserve resources for time-sensitive traffics. SRP uses bridge-by-bridge propagation for its messages and registers VLAN ID and group address before making Audio-Video (AV) stream reservations. In this study, we propose a simplified SRP scheme over the Software-defined Network (SDN) for in-vehicle bridged networks. The proposed scheme exploits the topology and bridge information of bridged networks. A centralized stream reservation procedure in the scheme replaces the bridge-by-bridge propagation for SRP reservations. The reservation procedure does not require VLAN ID and group address registration. We implemented a prototype of the proposed scheme and showed that reserved flows are well protected when links of bridges are overloaded.

CSRP: An Enhanced Protocol for Consistent Reservation of Resources in AVB/TSN

The IEEE Audio Video Bridging (AVB) Task Group (TG) was created to provide Ethernet with soft real-time guarantees. Later on, the TG was renamed to Time-Sensitive Networking (TSN) and its scope broadened to support hard real-time and critical applications. The Stream Reservation Protocol (SRP) is a key work of the TGs as it allows reserving resources in the network, guaranteeing the required quality of service. AVB's SRP is based on a distributed architecture, whereas TSN's is based on centralized ones. The distributed version of SRP is supported and used in TSN. Nevertheless, it was not designed to provide properties that are important for critical applications. In this article, we model SRP using UPPAAL and we study the termination and consistency. We verify that SRP does not provide such properties. Furthermore, we propose an improved protocol called Consistent Stream Reservation Protocol (CSRP) and we formally verify its correctness using UPPAAL.

Improving Worst-Case Delay Analysis for Traffic of Additional Stream Reservation Class in Ethernet-AVB Network.

With the increase in the number of Electronic Control Units (ECUs) and future requirements for vehicle functions, two SR (Stream Reservation) traffic classes may not be sufficient to ensure fulfilment of constraints for multiple traffic types with individual timing requirements transmitted in the Ethernet-AVB (Audio Video Bridging) networks. The goal of this paper is to determine the worst-case delay for an additional SR traffic class under the CBS (Credit-Based Shaper) algorithm. Delay evaluation is based on the impact analysis of CBS on different priority flows, particularly depending on when the credits of both SR class A and B drain from the worst-case perspective. More specifically, both the impact of CBS and the evolution trends of credit on different priority class flows are first analyzed from the worst-case perspective. Then, for an additional SR class, two types of worst-case delay models are established with the CBS configuration suggestions. Finally, an approach to calculate the worst-case queuing delay is proposed. Moreover, the worst-case end-to-end delay is determined by the network calculus approach and simulation. Numerical results show that the delay bounds of our models are tighter than those of other models, which is beneficial to the development of Ethernet-AVB for in-vehicle networking.

A Survey of Medium Access Mechanisms for Providing Robust Audio Video Streaming in IEEE 802.11aa Standard

The amendment of medium access control (MAC) in 802.11 has been published as the 802.11aa standard. The new standard enhances the quality of service (QoS) provisioning for robust audio–video (AV) streaming in wireless local area networks (WLANs). The 802.11aa standard is mainly an extension of the 802.11e, 802.11n, and 802.11v standards. In this survey, we describe the mechanisms of Medium Access Control (MAC) in 802.11aa in greater detail. The interworkings of the different network technologies of Quality of Service (QoS) WLAN and Ethernet are explained. We add mechanisms from the 802.1Q standard to complement 802.11aa regarding the stream reservation protocol and strict priority algorithm to provide a complete vision of the standard. Research challenges include incorporating a wide range of mechanisms in the 802.1Q wireline standard in the 802.11aa wireless standard. To enhance the interworking of the 802.1Q and 802.11aa standards, we propose to unify three mechanisms: the maps Access Categories (ACs), the transmit access queues, and transmission selection algorithm. This survey provides necessary guidelines for researchers and designers to implement future Wireless Local Area Network (WLAN) 802.11aa with an emphasis on the requirements for robust Audio-Video (AV) streaming.

다채널 멀티미디어 전송용 임베디드 Audio Video Bridging 플랫폼 설계 및 구현

In this paper, we designed an embedded audio video bridging (AVB) platform based on IEEE 802.1BA for real-time multimedia transmission in smart-car, smart-home, smart-theater, and then evaluated a performance of the implemented platform by analysis of IEEE 802.1AS (time synchronization protocol) and IEEE 802.1Qat (stream reservation protocol). Especially, the AVB Layer-2 protocol of MRP(Multiple Registration Protocol), MMAP(Multicast Address Acquisition Protocol), IEEE 1722, 1722.1 etc. was and implemented by linux based operating system. It is shown by interoperability tests with commercial products that the implemented platform transmits real-time multichannel AV data over AVB networks for Multichannel Multimedia Transmission. ☞ keyword : AVB, Mutlichannel HD-platform, QoS(Quality of Service), Inter-operability, Realtime Transmission, endpoint

Effectiveness of Existing Laws and Regulations to Prevent Encroachments of Stream Reservations

Sri Lanka, with more than 2500 years of hydraulic civilization, has constructed highly complex systems of irrigation in the Dry Zone. Kings formulated the rules in consultation with high officials in the Kings&rsquo; court. The King was the source of the laws. This ancient administrative system gradually changed after colonization and attention focused more on written rules and regulations of the government legislations than those based on customs, norms, and traditions of Sri Lanka. There are more than 50 legislations enacted in relation to the development and management of water resources along with the establishment of a large number of institutions. Despite all these, water resources are being degraded at an alarming rate. A preliminary study showed that there were adequate legal mechanisms and institutions to prevent water resources degradation. This study was carried out to determine the effectiveness of regulations and associated institutional arrangements to prevent stream encroachments. Two villages between Peradeniya and Gampola along the Mahaweli river were selected for the study. Questionnaire surveys, focus group discussions among institutional officers and interviews were conducted in these villages. The results showed that the existing regulatory mechanisms to protect stream reservation covered all aspects including eviction of encroachers. However, there are serious deficiencies in implementation of such regulations such as the lack of coordination among institutions, procedural lapses, political interference, and less enthusiasm of state employees to implement rules and regulations. The encroachers tend to occupy the reservations due to landlessness, poverty, and the social cohesion among their own communities. <br /><br /><strong>Keywords:</strong> Encroachment; Legislations and Stream reservations <br /><br />DOI: 10.4038/tar.v22i2.2822<br /><br /><em>Tropical Agricultural Research</em> Vol. 22 (2): 134 - 143 (2011)