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另一个网络特点在于最优的 Geode 性能是容错. Geode 操作依赖于网络服务, 网络故障对于Geode系统操作和性能有比较重要的影响. 而容错网络设计超出了本章所介绍的范围, 当在设计 Geode 解决方案时, 有一些比较重要的考虑. 对于本章的目的, 这些考虑通过网络三层架构设计来体现, 如下图所示:

This model uses a layered approach to network design, representing the network as a set of scalable building blocks, or layers. In designing Geode systems, network fault tolerance considerations include:

此模型使用典型的三层架构来设计网络, 以可扩展的模块化构建块或层级来表示网络. 在设计 Geode 系统时, 网络容错考虑如下设置:

• 接入层冗余设计 – 接入层是第一个入口点进入到网络边界设备和主机设备, 如 Geode 服务器. 对于Geode 系统, 在接入网络层中应该有属性来支持高可用, 包括: 
  ++ Operating system 高可用特性, 例如 Access layer redundancy – The access layer is the first point of entry into the network for edge devices and end stations such as Geode servers. For Geode systems, this network layer should have attributes that support high availability including: ++ Operating system high-availability features, such as Link Aggregation (EtherChannel or 802.3ad), which provide higher effective bandwidth and resilience while reducing complexity. ++ Default gateway redundancy using dual connections to redundant systems (distribution layer switches) that use 提供了更高效的带宽和弹性, 减少了复杂度. 
  ++ 默认的网关冗余, 使用了双连接到冗余系统 (汇聚层交换机) , 此交换机使用 Gateway Load Balancing Protocol (GLBP), Hot Standby Router Protocol (HSRP), or 或者 Virtual Router Redundancy Protocol (VRRP). This provides fast failover from one switch to the backup switch at the distribution layer. ++ Switch redundancy using some form of Split . 这提供了故障快速切换的高可用性. 
  ++ Switch 容错, 使用一些Split Multi-Link Trunking (SMLT). The use of SMLT not only allows traffic to be load-balanced across all the links in an aggregation group but also allows traffic to be redistributed very quickly in the event of link or switch failure. In general the failure of any one component results in a traffic disruption lasting less than half a second (normal less than 100 milliseconds).
• Distribution layer redundancy – The distribution layer aggregates access layer nodes and creates a fault boundary providing a logical isolation point in the event of a failure in the access layer. High availability for this layer comes from dual equal-cost paths from the distribution layer to the core and from the access layer to the distribution layer. This network layer is usually designed for high availability and doesn’t typically require changes for Geode systems.
• 使用 SMLT 不仅允许在汇聚层流量跨所有链路是负载均衡的, 而且还允许流量当链路或交换机发生故障时进行快速重分布. 通常情况, 任意一个模块故障将导致无流量, 0.5秒之内 (正常情况下小于 100 毫秒).
• 汇聚层冗余设计 – 汇聚层网络聚合接入层的节点, 在接入层发生故障之后, 创建容错边界来提供逻辑隔离点. 高可用源自汇聚层到核心层、汇聚层到接入层的双冗余链路设计. 此网络层通常被设计用于高可用, 不需要为 Geode系统做更改.
• 核心层冗余设计 – 核心层作为骨干网提供网络服务. 核心层需要极快地弹性, 因为所有的网络访问都依赖于它连接. 在核心层使用 L3交换机环境物理硬件增强和 P2P 的互联. 这个核心层被设计成高可用层, 此网络层通常被设计用于高可用, 不需要为 Geode系统做更改Core layer redundancy – The core layer serves as the backbone for the network. The core needs to be fast and extremely resilient because everything depends on it for connectivity. This network layer is typically built as a high-speed, Layer 3 switching environment using only hardware-accelerated services and redundant point-to-point Layer 3 interconnections in the core. This layer is designed for high availability and doesn’t typically require changes for Geode systems.

最佳实践

Geode systems depend on network services and network failures can have a significant impact on Geode operations and performance. As a result, network fault tolerance is an important design goal for Geode solutions. Best practices for achieving this goal include:

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