Notes On Chapter Thirty-Three -- Trends in Networking Technologies and Uses

• 33.1 Introduction
  
  
  • Recent developments
  • Longer-term research
  
  
• 33.2 The Need for Scalable Internet Services
  
  
  • A centralized server and/or its access network can become a bottleneck.
  • This motivates much investigation and development of scaling architectures.
  
  
• 33.3 Content Caching (Akamai)
  
  
  • ISPs often cache static web pages.
  • Some companies offer a distributed caching service.
  • For example, Akamai has a set of servers all over the Internet.
  • An organization can pay Akamai for the privilege of pre-loading Akamai server caches with the organization's web pages.
  • Links on the organization's web site direct customer clicks to Akamai server content.
  • The organization is allowed to send updates of their 'content' to the Akamai caches.
  • The scheme reduces load on the servers of the organization.
  
  
• 33.4 Web Load Balancers
  
  
  • Refer to Figure 33.1.
  • Web server optimization gets a lot of attention because businesses rely on the web to make sales.
  • A load balancer is a device that distributes incoming requests among multiple computers running identical web servers.
  • Typically the servers share the same customer database.
  • The load balancers have the ability to direct a series of requests from the same source to the same server.
  
  
  
  
• 33.5 Server Virtualization
  
  
  • Some systems support process migration - the capability of an executing program to move to another computer.
  • Given infrastructure for process migration, it is possible for a server on an overloaded machine to move to another machine where resources like CPU time are in more plentiful supply.
  
  
• 33.6 Peer-to-Peer Communication
  
  
  • P2P is a technology used to increase the speed of file downloads.
  • Clients fetch pieces of the file.
  • Various servers all over the Internet have various pieces of the file.
  • Clients try to fetch pieces from nearby servers.
  • Clients agree to be servers for the pieces of the file they have downloaded.
  • Well-known examples were created mainly for downloading music files: e.g. Napster & Kazaa
  
  
• 33.7 Distributed Data Centers and Replication
  
  
  • Sites such as Google get so much traffic that they have resorted to another approach.
  • When a browser connects with DNS to resolve the name www.google.com, different IP numbers are 'suggested' at different times.
  • This has the effect of balancing the load over multiple Google data centers distributed in various geographic locations.
  
  
• 33.8 Universal Representation (XML)
  
  
  • XML allows programmers to choose arbitrary tags so the documents can be understood by multiple applications.
  • Documents can include a style sheet that specifies legitimate document structure.
  • Uses:
    • on interface between web server and database
    • load balancers parsing XML
    • XML controlling downloads in mobile devices
    • XML representing specifications used by network management systems
  
  
• 33.9 Social Networking
  
  
  • Starting in the early 2000's there has been a significant increase in the production of content by individual users - for example blogs, chats, Facebook, MySpace and YouTube.
  • One implication is that the typical user is uploading data more than previously.
  
  
• 33.10 Mobility and Wireless Networking
  
  
  • Users now expect to be connected continuously to the Internet.
  • Wireless technologies receive a lot of attention and are targeted for rapid development.
  • Mobile phone networks are converging with the Internet.
  • Mobile computer users rely on WiFi and Virtual Private Networks (VPN)
  
  
• 33.11 Digital Video
  
  
  • Cable companies are replacing analog service with digital.
  • Digital TV content is provided over packet networks.
  • There is increasing use of IPTV.
  • The Internet is converging with the television and radio networks.
  • There is less and less difference between computers and television sets.
  • On demand video is easier to deploy this way.
  • Pause, rewind, and live-capture are easier to control.
  
  
• 33.12 Higher-Speed Access and Switching
  
  
  • Some cellular providers data rates up to 50 Mps.
  • Some ISPs offer Gigabit speeds to residential customers.
  • Backbone network links may soon reach rates of 40 Gbps.
  • It's not far-fetched to predict such rates will be provided to homes and small businesses in the not-to-distant future.
  • That is enough bandwidth for high-definition video.
  
  
• 33.13 Cloud Computing
  
  
  • Companies outsource IT operations to cloud providers that maintain data centers that include computational and storage services.
  • Flexibility is a big advantage. Companies only pay for what they use and they don't have to provision their local shops for peak resource consumption.
  
  
• 33.14 Overlay Networks
  
  
  • Computers connected to the Internet can utilize tunneling.
  • When X transmits a packet to Y, X encapsulates the packet in an outer datagram.
    
    
    
    
  • The intermediate computers on the route don't need to use the the contents of the inner datagram, which is encrypted by the sender.
  • This scheme can also be used to partition the network logically, so that certain traffic is restricted to only certain machines.
  • Any points of intersection of separate networks can be chosen with care and hardened.
  • Switches and/or routers can also define tunnels.
  
  
• 33.15 Middleware
  
  
  • Middleware facilitates coordination among applications running on multiple platforms.
  • Middleware typically operates at the level between applications and the operating system.
  • Shibboleth is an example, which provides password management and validation across a set of organizations.
  
  
• 33.16 Widespread Deployment of IPv6
  
  
  • IPv4 has adapted much better than many people expected.
  • We are somehow doing without much penetration of IPv6.
  • We could remove NAT from the Internet and have end-to-end addressing everywhere but it would require replacing a huge amount of networking equipment and software.
  • There's no actual need for IPv6 now, but the transition has started, and it will continue.
  • Google wants IPv6 so that all devices will have unique addresses - that way Google can target ads more individually.
  • Cellular operators know they have to replace equipment when they transition to IP, and they don't want to gamble on using IPv4.