| 1. |
- Ashjaei, Mohammad, et al.
(författare)
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A Compact Approach to Clustered Master-Slave Ethernet Networks
- 2012
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781467315739 ; , s. 157-160
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Konferensbidrag (refereegranskat)abstract
- Ethernet switches are increasingly used in real-time distributed systems as a technical solution to guarantee the timeliness in communications. However, there are still limitations related to real-time behavior caused by the limited number of priority levels and the possibility of memory overruns with consequent message losses. These limitations can be eliminated using a master/slave technique such as proposed by the FTT paradigm. This led to the FTT-SE protocol that schedules transmissions centrally in a master node. While this protocol has already been well studied and investigated for small networks with a single switch, its extension to larger networks is still an open issue. In this paper we propose a compact clustered solution to scale the FTT-SE protocol to networks of multiple switches by organizing the network in sub-networks composed of one master and one switch each and which can be connected directly, without bridges. This paper also shows how the timeliness of the traffic can still be enforced. The validation is currently on-going.
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| 2. |
- Behnam, Moris, et al.
(författare)
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Analysis and Optimization of the MTU in Real-Time Communications over Switched Ethernet
- 2011
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Ingår i: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA. ; , s. Art.nr. 6059021-
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Konferensbidrag (refereegranskat)abstract
- The Flexible Time-Triggered communication over Switched Ethernet protocol (FTT-SE) was proposed to overcome the limitation of guaranteeing the real-time communication requirements of conventional switches, and at the same time to support reconfiguration of dynamic adaptive systems. The protocol fragments large messages into a sequence of packets that are individually scheduled. The maximum transmission unit (MTU), that restricts the packets size, has a significant effect on the schedulability of the packets. In this paper, we investigate the problem of selecting the optimal MTU size that maximizes the schedulability of real-time messages. We propose two algorithms to find optimal/sub-optimal values of MTU; the first one finds an optimal solution but exhibits high computational complexity, while the second one is sub-optimal but exhibits a lower computational complexity. Finally, we evaluate our proposed algorithms by means of simulation studies and compare their results with the results of assigning MTU to the maximum packet size that the protocol can allow.
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| 3. |
- Iqbal, Zahid, et al.
(författare)
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Implementing Hierarchical Scheduling on COTS Ethernet Switches Using a Master/Slave Approach
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems (SIES'12), Conference proceedings. - 9781467326834 - 9781467326858 ; , s. 76-84
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Konferensbidrag (refereegranskat)abstract
- Hierarchical scheduling is instrumental to efficiently deploy component-based designs and achieve composability. It allows partitioning resources into multiple levels, hiding the complexity within each partition behind its respective interface. In this paper we focus on the network resource, particularly on Ethernet using ordinary COTS switches, and we show how hierarchical scheduling can be efficiently deployed using a master/slave approach that enforces the temporal properties of the partitions. We use the FTT-SE protocol for being open source and a bandwidth efficient master/slave alternative currently available for real-time communication over Ethernet. We present a response-time analysis for the traffic submitted within each partition and we validate it using experimental results obtained from a prototype implementation. In particular, the results highlight the strong partitioning capabilities of our approach, with full temporal isolation across partitions in different branches of the hierarchy.
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| 4. |
- Marau, Ricardo, et al.
(författare)
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Controlling Multi-Switch Networks for Prompt Reconfiguration
- 2012
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781467315739 ; , s. 233-242
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Konferensbidrag (refereegranskat)abstract
- Recent trends in distributed embedded systems, such as those found in avionics and trains, have shown an increase in the amount and heterogeneity of the information that needs to be exchanged, together with a growing importance of supporting dynamic reconfiguration and adaptive behaviors. In this paper we focus on Ethernet technologies with real-time reconfiguration support and we address the case of middle-size networking infrastructures with a few switches. We use the FTT-SE protocol with the needed adaptations to support dynamic heterogeneous real-time transactions in multi-hop networks. The paper presents a worst-case response-time analysis that provides timeliness guarantees, improving the results obtained with another previous analysis, decreasing the needed network capacity for guaranteed schedulability by 25% on average. Practical experiments and simulation results validate the proposed approach and analysis.
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| 5. |
- Marau, Ricardo, et al.
(författare)
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Server-based real-time communications of Switched Ethernet
- 2008
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Ingår i: Proceedings of the 1st Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'08) in conjunction with the 29th IEEE International Real-Time Systems Symposium (RTSS'08), Barcelona, Spain.
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Konferensbidrag (refereegranskat)
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| 6. |
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| 7. |
- Mifdaoui, Ahlem, et al.
(författare)
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Exploring alternatives to use master/slave full duplex switched Ethernet for avionics embedded applications
- 2012
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Konferensbidrag (refereegranskat)abstract
- The complexity of distributed real-time systems, including military embedded applications, is increasing due to an increasing number of nodes, their functionality and higher amounts of exchanged data. This higher complexity imposes major development challenges when nonfunctional properties must be enforced. On the other hand, the current military communication networks are a generation old and are no longer effective in facing such increasingly complex requirements. A new communication network, based on Full Duplex Switched Ethernet and Master/slave approach, has been proposed previously. However, this initial approach is not efficient in terms of network bandwidth utilization. In this paper we propose two new alternative approaches that can use the network bandwidth more efficiently. In addition we provide a preliminary qualitative assessment of the three approaches concerning different factors such as performance, scalability, complexity and flexibility.
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| 8. |
- Santos, Rui, et al.
(författare)
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Flexible, Efficient and Robust Real-Time Communication with Server-based Ethernet Switching
- 2010
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Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS 2010. - 9781424454617 ; , s. 131-140
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Konferensbidrag (refereegranskat)abstract
- The information exchanged in Networked Embedded Systems is steadily increasing in quantity, size, complexity and heterogeneity, with growing requirements for arbitrary arrival patterns and guaranteed QoS. One of the networking protocols that is becoming more common in such systems is Ethernet and its real-time Ethernet variants. However, they hardly support all the referred requirements in an efficient manner since they either favour determinism or throughput, but not both. A potential solution recently proposed by the authors is the Server-SE protocol that uses servers to confine traffic associated to specific applications or subsystems. Such an approach is dynamically reconfigurable and adaptive, being more bandwidth efficient while providing compos ability in the time domain. This paper proposes integrating the servers inside the Ethernet switch, boosting both the flexibility and the robustness of Server-SE, allowing, for example, the seamless connection of any Ethernet node. The switch is an FTT-enabled Ethernet Switch and the paper discusses two specific ways of integrating the servers, namely in software or in hardware. These options are described and compared analytically and experimentally. The former favours flexibility in the servers design and management while the latter provides lower latency.
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| 9. |
- Santos, Rui, et al.
(författare)
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Implementing Server-Based Communication within Ethernet Switches
- 2009
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Ingår i: Proceedings of the 2nd Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'09) in conjunction with the 30th IEEE International Real-Time Systems Symposium (RTSS'09). - Washington, DC, USA.
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Konferensbidrag (refereegranskat)
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| 10. |
- Santos, Rui, et al.
(författare)
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Improving the efficiency of Ethernet switches for real-time communication
- 2010
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Konferensbidrag (refereegranskat)abstract
- The growth of connectivity in general, including in networked embedded systems, is continuously increasing the amount and diversity of information that needs being exchanged among nodes. The arrival pattern of such traffic is also frequently bursty and jittered, negatively impacting the system performance. In this paper we focus on switched Ethernet and we aim at providing flow-based dynamic scheduling that allows handling bursty and jittered traffic in a bandwidth efficient way. For that we use adaptive resource-reservation, associating servers to flows or groups of flows that contain the impact that a misbehaving flow can have. These servers can be adapted on-line to make a better use of the available bandwidth.
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