Bài giảng "Mạng máy tính nâng cao: Content distribution networks" cung cấp cho người học các kiến thức: Single server, poor performance, web caching, limitations of web caching, content distribution networks,. . | Bài giảng Mạng máy tính nâng cao: Content distribution networks - Lê Ngọc Sơn Content Distribution Networks (CDNs) MẠNG MÁY TÍNH NÂNG CAO Single Server, Poor Performance qSingle server qPopular content § Single point of § Popular site failure § “Flash crowd” (aka § Easily overloaded “Slashdot effect”) § Far from most clients § Denial of Service attack 2 Web Caching 3 4 Proxy Caches origin qReactively replicates server popular content Proxy server qSmaller round-trip client times to clients qReduces load on origin servers client qReduces network load, and bandwidth costs qMaintain persistent TCP connections Forward Proxy qCache close to the client Proxy § Improves client performance client server § Reduces network provider’s costs qExplicit proxy § Requires configuring browser client qImplicit proxy § Service provider deploys an “on path” proxy § that intercepts and handles Web requests 5 Reverse Proxy qCache close to server origin § Improve client performance server § Reduce content provider cost Proxy server § Load balancing, content assembly, transcoding, etc. qDirecting clients to the proxy § Map the site name to the IP address of the proxy origin server 6 Google Design . . . Servers Data Centers Servers Router Router Private Backbone Reverse Reverse Proxy Proxy Internet Requests Client Client Client Limitations of Web Caching qMuch content is not cacheable § Dynamic data: stock prices, scores, web cams § CGI scripts: results depend on parameters § Cookies: results
