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• Keep Geode members and clients on the same LAN Keep all members of a Geode distributed system and their clients on the same LAN and preferably on the same LAN segment. The goal is to place all Geode cluster members and clients in close proximity to each other on the network. This not only minimizes propagation delays, it also serves to minimize other delays resulting from routing and traffic management. Geode members are in constant communication and so even relatively small changes in network delays can multiply, impacting overall performance.
• Use network traffic encryption prudently Distributed systems like Geode generate high volumes of network traffic, including a fair amount of system management traffic. Encrypting network traffic between the members of a Geode cluster will add processing delays even when the traffic contains no sensitive data. As an alternative, consider encrypting only the sensitive data itself. Or, if it is necessary to restrict access to data on the wire between Geode members, consider placing the Geode members in a separate network security zone that cordons off the Geode cluster from other systems.
• Use the fastest link possible Although bandwidth alone does not determine throughput - all things being equal, a higher speed link will transmit more data in the same amount of time than a slower one. Distributed systems like Geode move high volumes of traffic through the network and can benefit from having the highest speed link available. While some Geode customers with exacting performance requirements make use of InfiniBand network technology that is capable of link speeds up to 40Gbps, 10GbE is sufficient for most applications and is generally recommended for production and performance/system testing environments. For development environments and less critical applications, 1GbE is often sufficient.

高吞吐量

In addition to low latency, the network underlying a Geode system needs to have high throughput. ISPs and the FCC often use the terms 'bandwidth' and 'speed' interchangeably although they are not the same thing. In fact, bandwidth is only one of several factors that affect the perceived speed of a network. Therefore, it is more accurate to say that bandwidth describes a network’s capacity, most often expressed in bits per second. Specifically, bandwidth refers to the data transfer rate (in bits per second) supported by a network connection or interface. Throughput, on the other hand, can often be significantly less than the network’s full capacity. Throughput, the useable link bandwidth, may be impacted by a number of factors including:

另外对于低延时来讲, Geode 系统的网络需要有高吞吐量. ISPs 和 FCC 经常使用术语'带宽'和'速度', 虽然它们并不是一回事. 事实上, 带宽只是众多影响因素之一. 因此, 更准确地说

带宽描述了一个网络能力, 通常情况下以 bit/s 来表示. 更进一步地, 带宽涉及到数据传输速率 (bits/s) , 通过一个网络连接或接口来支持. 吞吐量,经常是小于网络的全部传输能力. 吞吐量, 可用的链接带宽, 可能受以下的因素影响:

• 协议低效 – TCP 是一个适配协议, 搜寻在网络资源上的负载均衡需求,  高效利用如下的网络基础设施Protocol inefficiency – TCP is an adaptive protocol that seeks to balance the demands placed on network resources from all network peers while making efficient use of the underlying network infrastructure. TCP detects and responds to current network conditions using a variety of feedback mechanisms and algorithms. The mechanisms and algorithms have evolved over the years but the core principles remain the same: ++ All TCP connections begin with a three-way handshake that introduces latency and makes TCP connection creation expensive ++ TCP slow-start is applied to every new connection by default. This means that connections can’t immediately use the full capacity of the link. The time required to reach a specific throughput target is a function of both the round trip time between the client and server and the initial congestion window size. ++ TCP flow control and congestion control regulate the throughput of all TCP connections. ++ TCP throughput is regulated by the current congestion window size.
• Congestion – this occurs when a link or node is loaded to the point that its quality of service degrades. Typical effects include queuing delay, packet loss or blocking of new connections. As a result, an incremental increase in offered load on a congested network may result in an actual reduction in network throughput. In extreme cases, networks may experience a congestion collapse where reduced throughput continues well after the congestion-inducing load has been eliminated and renders the network unusable. This condition was first documented by John Nagle in 1984 and by 1986 had become a reality for the Department of Defense’s ARPANET – the precursor to the modern Internet and the world’s first operational packet-switched network. These incidents saw sustained reductions in capacity, in some cases capacity dropped by a factor of 1,000! Modern networks use flow control, congestion control and congestion avoidance techniques to avoid congestion collapse. These techniques include: exponential backoff, TCP Window reduction and fair queuing in devices like routers. Packet prioritization is another method used to minimize the effects of congestion.

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