Life as a Network

May 3, 2005

David Lease

The human life cycle is a process that we often abstract to include many of the things we create. As a logical and familiar model, it is easily applied to such things as the life of a car.

And perhaps this car breaks down one too many times, or we have children and need more space or for a host of other reasons we determine that it is time to replace it with a new one.

We visualize the need for better service, access, technology, or perhaps even capacity.

Like drivers and their cars, software developers view life cycles as intrinsic to networks. The life cycle process can be described as conception, gestation, birth, maturation, decline, and eventually death.

The cycle of a network's life is similar: idea or concept, design and implementation, operation, legacy integration, and eventually transformation. This article will examine the development or transformation of a network using a life-cycle model and demonstrate how this process can benefit an organization.

There are four basic steps to the transformation process:

  • Assessment (Conception).
  • Design and definition (Gestation).
  • Implementation (Birth).
  • Maintenance and Support (Maturation and Decline).
  • Assessment

    Conception, or the beginning of the process, occurs when an organization realizes that change is needed. After obtaining the necessary approvals and securing funding, the transformation process has begun.

    The process of transformation requires as much understanding of the past and current network as what the network will need to be in the future. This task is not as simple as it would seem, for the counting and classification of switches and routers is merely the first step.

    A comprehensive survey and documentation of all active and passive components is required to determine if anything is re-usable, if right-of-ways or building access points currently in place will meet your needs, and to determine if environmental controls, fire suppression, and backup power are sufficient to support any new equipment.

    This is by no means a comprehensive list, but is a good indicator of what is generally required.

    In the assessment phase, you will want to evaluate what sensors will be needed in the network. The impact of adding various chemical, biological, radiological, environmental, and video sensors to networked systems can be significant. Increasingly, such monitoring equipment is required in various rooms, buildings, and campuses as a result of heightened security concerns.

    While individual sensors may contribute less significantly to the overall network load, large numbers of these sensors acting simultaneously may cause congestion. The resulting data loss can impede the ability to respond to an incident and can inhibit an organization's ability to determine the cause(s) during the critical forensic analysis phase that occurs post-incident.

    It is important to point out the specific need to address sensors in this phase because these types of technologies are becoming more common and too often, sensors are implemented into a network without proper planning.

    As you continue the assessment, gather all existing documentation and compare it to the infrastructure. Update it as you go.

    While it may appear that more emphasis is being put on assessment than on the other areas, that is because it is the most critical element; the other three areas will not function well over time if this step is hurried or overlooked.


    After assessment, the seed is planted and you're "pregnant" with the idea of a new environment to operate in. But before birth occurs, like any proud parent, you are planning for its future. This requires architecture and design.

    Network design is sometimes looked upon as a process of simply connecting the dots. This is the simplest of design and does not meet the needs of many organizations.

    Good network design takes into account all of the servers, applications, storage modules, projected usage patterns, and a well-educated estimate as to future expansion of the network (users and sites.) Robust designs allow the dynamic addition of users and sites, along with the associated traffic, with little or no impact to the original user set.

    Begin with an architecture that defines the overall functions of the network but doesn't specify equipment. This is similar to a mechanical engineer designing a vehicle that can accommodate a large payload, or have the capacity to reach 0 to 60 in 6 seconds.

    Once accomplished, you can move to a design phase where you choose technologies and vendors, and finalize details such as location, power, fire support, security, access, and other areas are finalized. Include the network management function, spares and maintenance plans, and network elements for help desk as part of the architecture and design functions.

    Both the architecture and designs should have written documentation explaining details along with drawings at various levels of complexity. It is critical that the high level perspective of this documentation be understandable by non-technical personnel, as these will be presented for review to executive teams for final approval of funding.


    Like a child, a network goes through different stages before becoming an adult. The network may come online in segments, but, as with any building project, implementation begins from the ground up.

    In the network world this denotes the elements at the bottom of the open system interconnection (OSI) stack or the cabling. Cable plant is often the most difficult piece to implement, especially if you're required to dig trenches to lay cable between buildings or across town.

    These are also the most expensive elements and the longest to deploy as they usually require environmental impact studies, special building permits, and depend on weather conditions in some areas of the country. Short haul wireless solutions can sometimes overcome the need to trench cable.

    Building new networks from scratch is often much easier than transforming existing infrastructures, as there is no need to plan around current users. In the case of transforming existing systems, construction must occur in parallel with the functioning network.

    After physical build out is complete, the logical elements of routing, security, numbering and naming are installed and tested. To minimize impact to the business, testing must be coordinated with users, especially since they usually involve outage periods or transitioning users from one network to another.

    This can be especially tricky when the site also holds applications or storage for mission critical systems. If possible these sites should be tested either first or last in sequence, or they may be transitioned to temporary facilities to minimize impact to the enterprise.


    Once a network matures and reaches adulthood, it occasionally needs medical attention.

    Circuits, routers, switches, cables, connectors and the like may suffer failure or degradation. Routers need logical "tune ups," users and applications come and go, or new server equipment and storage is needed.

    And like an annual physical, all of this equipment and their associated configurations need to be reviewed on a regular schedule to insure optimum performance. It is critical that the documentation of all aspects of the network be maintained and available, just as a medical record for a human must be current and accurate to insure proper treatments are applied.

    The transition from an aging, suboptimal networking environment to a modern high-performance network is an involved process. We are often required to relinquish processes, personnel, and equipment that has in the past seen us through difficult times.

    As in the cycle of life, this passing of the familiar and safe can be unsettling. And, as in the cycle of life, the birth of a new environment can be welcomed with much celebration.

    David Lease is chief architect of Netco Government Services, a network design, management, and engineering firm serving government agencies. He can contacted at


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