Performance Evaluation of Computer Networks with Broadcast Channels Taking into Account Higher Level Protocols

已经对具有广播频道的计算机网络(广播计算机网络)进行了许多性能研究。然而，它们中的绝大多数只涉及多个接入协议，而没有考虑更高级别的协议。这项研究的目的是评估广播计算机网络的性能，除了考虑多个接入协议之外，还考虑更高级别的协议。在这项研究中，我们认为确认(ACK)问题是实现这一目标的第一步。这是因为ACK包的传输是由高层协议进行的，而ACK是考虑高层协议对系统性能影响的最简单形式。我们首先分析了考虑ACK流量的时隙1-持久CSMA/CD局域网。通过平衡点分析(EPA)，对系统的吞吐量和平均响应时间特性进行了评估，并论证了系统的稳定性行为。研究了两种情况：1)结合了类似于确认以太网的基于分组的优先级功能，以及2)没有提供优先级功能。优先级确认方案保证ACK分组的无冲突传输，而非优先级确认方案不能保证这一点。接下来，我们分析了ALOHA预留卫星网络中的两种确认机制。在这两种方案中，在相同的控制子帧中发送ACK分组和预留分组。与上述CSMA/CD网络的情况一样，我们根据是否包含优先级功能来区分这两种确认方案。通过EPA，我们从吞吐量、平均响应时间和系统稳定性三个方面分析了这两种方案的性能，并研究了缓冲CSMA/CD网络中的传输方案。

Many performance studies have been made of computer networks with broadcast channels (broadcast computer networks). However, the great majority of them are concerned only with multiple access protocols and do not take into account higher level protocols. The objective of this study is to evaluate the performance of the broadcast computer networks taking into account higher level protocols in addition to multiple access protocols. In this study, we consider acknowledgment (ACK) problems as the first step to reach this goal. This is because the transmission of ACK packets is conducted by higher level protocols and ACK is the simplest form of taking into account the influence of higher level protocols on the system performance.We first analyze slotted 1-persistent CSMA/CD local area networks taking into account ACK traffic. By means of the equilibrium point analysis (EPA), the throughput and average response time characteristics are evaluated, andthw system stability behavior is demonstrated. Two cases are examined: 1) packet-based priority functions similar to that of Acknowledging Ethernet are incorporated, and 2) no priority function is provided. The priority acknowledgment schemes guarantee collision-free transmission of ACK packets, while the nonpriority one does not guarantee it. It is shown how the performance improvement is made by the priority acknowledgmet schemes.Next, we analyze two acknowledgment schemes for the ALOHA-Reservation satellite network. In both scheme, ACK packets and reservation packets, are transmitted in the same control subframe. As in the above case of CSMA/CD networks, we differentiate between the two acknowledgment schemes depending on whether a priority function is incorporated or not. By means of EPA, we analyze the performance of the two schemes in terms of throughput, average response time and system stability.In addition to the ACK problems, we also study transmission schemes for buffered CSMA/CD networks.