Conclusions about network centralization and decentralization
Network centralization and network decentralization are about making changes. When making such pervasive changes, experts recommend that you consider these guiding principles: know what specific problem you are solving; understand your motivation for making the change; centralize as much as makes sense for today; recognize that as in rolling out any new service, it requires careful planning; and, most important, listen to the customers. Test your knowledge with several questions about what you've read.
This summary of network centralization and network decentralization draws together the tips and best practices outlined in five previous sections: Introduction to network centralization/decentralization, the basics of network centralization/decentralization, candidates for centralization, candidates for decentralization and case studies in centralization/decentralization. Re-read those earlier sections to help you complete the exercises below.
Centralization and decentralization are complicated topics. Neither is always the right solution. Technical issues, such as server administration, as well as nontechnical issues, such as organizational structure, can be centralized or decentralized.
Both topics are about making changes. When making such pervasive changes, we recommend that you consider these guiding principles: know what specific problem you are solving; understand your motivation for making the change; centralize as much as makes sense for today; recognize that as in rolling out any new service, it requires careful planning; and, most important, listen to the customers.
It is useful to learn from other people's experiences. The USENIX LISA conference has published many case studies (Epp and Baines 1992; Ondishko 1989; Schafer 1992b; and Schwartz, Cottrell, and Dart 1994). Harlander (1994) and Miller and Morris (1996) describe useful tools and the lessons learned from using them.
Centralizing purchasing can be an excellent way to control costs, and our example showed that it can be done not by preventing people from getting what they want, but by helping them make purchases in a more cost-effective manner.
We ended with a discussion of outsourcing. Outsourcing can be a major force for centralization and will be a large part of system administration for a very long time, even under different names.
Centralization Rules of Thumb Every site is different, but we have found that, as an informal rule of thumb, centralization of the following services is preferred once a company grows large enough to have multiple divisions:
- Network security
- Internet connectivity
- WAN services
- LAN deployment and operations
- Email services
- Desktop deployment and life-cycle management
- Storage within a data center
- Web services with external access
- IP address allocation and DNS management
- How centralized or decentralized is your current environment? Give examples.
- Give an example of a service or an aspect of your organization that should be centralized.
- Give an example of a service or an aspect of your organization that should be decentralized.
- We describe decentralizing email servers to achieve better reliability. How would you construct a similar architecture for print servers?
- Describe a small centralization project that would improve your current system.
- Share your favorite outsourcing horror story.
Network centralization and decentralization
Candidates for centralization
Candidates for decentralization
Reproduced from the Addison-Wesley Professional book The Practice of System and Network Administration, 2nd Edition, by Thomas A. Limoncelli, Christina J. Hogan and Strata R. Chalup. ISBN 978-0321492661. Copyright 2007, Addison-Wesley Professional. Reproduced by permission of Pearson Education Inc., 800 East 96th St., Indianapolis, IN 46240. Written permission from Pearson Education Inc. is required for all other uses.