读书笔记： 《Content Networking Fundamentals》
在生活的各个方面，需求导致新的创造和发明，网络计算也是一样，它的发展伴随着不断增长的用户需求：更加丰富的内容，更多的带宽，更多的可靠性。要完成这些要求，首先你必须解决以下四个方面：
Scalability and Availability
Bandwidth and Response Times
Customization and Prioritization
Security, Auditing, and Monitoring
Scalability and Availability
Scaling the Application
content networking 可以为应用提供未来增长的可扩展空间，而不需要改变应用工作的方式，只需要微小的改变网络架构。包括以下的服务：
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Content edge delivery Positioning application content away from the origin server, and in closer proximity to clients, scales the application by offloading requests to the content network. 将内容放在更加接近用户的地方。
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Enhanced content delivery with IP multicast, stream-splitting, and resource reservation IP multicast and stream-splitting scales the network by avoiding replication of identical flows over the same network link, thus minimizing end-to-end bandwidth consumption of content delivered to a large number of users. Resource reservation scales the application by manipulating network parameters to expedite application traffic delivery.通过组播和流分割技术，避免通过同样的网络连接（？)复制同样的内容，这样最小化了大量用户的端到端的带宽消耗。资源预留可以加快应用的通信传输。
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Content transformation and prioritization Transformation provides conversion of content within the network without further burdening of origin servers. Prioritization enables custom network delivery of application traffic.
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Flash crowd protection Protection against sudden, but valid, traffic spikes directed toward an application is important to maintaining service levels to customers. 需要在突发的大流量下维持服务水平。
Increasing Application Availability
包括以下部分：
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Content switching Increases availability by replicating origin server content across numerous identical systems, either within the same data center or across globally distributed data centers. 在多个相同系统复制原始服务器的内容，他们可以在同一个数据中心或者是跨全球的数据中心
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Session redundancy Session redundancy provides failover from one network device, such as a firewall or load balancer, to an identical device without dropping existing TCP connections. 在网络设备(firewall or LB)失效切换的时候不丢失已有的tcp连接。
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Router redundancy Protocols, such as Hot Standby Router Protocol (HSRP) and Virtual Router Redundancy Protocol (VRRP), provide router gateway redundancy by having two routers or load balancers share a virtual IP (VIP) and MAC address for clients to use as their default gateway. If either fails, the other will take over within seconds.
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IP routing redundancy Dynamic IP routing protocols, such as OSPF, EIGRP, and IS-IS, provide availability within a routing domain by maintaining multiple paths to each network in the routing table.
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Layer 2 switching redundancy Spanning tree and Cisco Etherchannel provides Layer 2 redundancy in a switched environment.