S 2.142 Development of a network realisation plan

Initiation responsibility: IT Security Officer, Head of IT

Implementation responsibility: Administrator

In drawing up a network implementation plan, you must be differentiate between whether the network is to be designed completely from scratch, or the existing conception is to be modified, and/or expanded.

If the network is planned completely from scratch, the required steps must be derived from the network concept drawn up (see also S 2.141 Development of a network concept). In this case, the network is designed, upon completion of the planning phase, by routing the required communication cables, setting up rooms for the technical infrastructure, installing the supplying technical infrastructure, integrating the necessary coupling elements (bridges, switches, routers, etc.), setting up network management stations, installing the corresponding network adapters into the terminal devices, up to the configuration of these terminal devices.

If an existing network is to be modified or expanded, the network concept drawn up in accordance with S 2.141 Development of a network concept must be compared to the existing environment according to S 2.139 Survey of the existing network environment by means of a target-actual comparison. Based on the differences, an implementation plan for the so-called network migration can be drawn up taking into consideration the safeguards mentioned above. In doing so, it must be taken into account that the implementation-related effort increases the more the network concept differs from the actual condition.

Exemplary migration of a "shared Ethernet" to a "switched Fast-Ethernet"

Normally, the migration from one network topology to another is performed gradually. Such a migration from a "shared Ethernet" to a Fast-Ethernet with switching technology is outlined as an example in the following. However, the general conditions must be reviewed thoroughly and incorporated into an appropriate migration concept for practical implementation.

• Migration step 1
  
  In the first migration step, the existing backbone can be replaced by a Fast-Ethernet backbone or designed newly, if necessary. The remainder of the shared Ethernet segments are connected using the network components of the backbones that must also support standard Ethernet accordingly.
• Migration step 2
  
  Design of a structured cabling, i.e. the transition from a standard Ethernet with stub to a cabling concept where every workplace is connected to a distribution room in a star-shaped manner, without compromising on the topological bus structure.
• Migration step 3
  
  The servers are connected centrally to a switch with Fast-Ethernet ports (installation in a so-called server farm).
• Migration step 4
  
  Users requiring high bandwidths are also connected with Fast-Ethernet by replacing the corresponding interfaces.
• Migration step 5
  
  Migration of the remainder of the Ethernet segments to a completely switched system. For this, Ethernet switches can be connected to the Fast-Ethernet switches of the backbone, for example.

Review questions:

• Complete replanning of a network: Are the necessary implementation phases derived from the network concept drawn up?
• Modification of an existing network: Are the differences between the network concept and the actual condition of the network determined within the framework of a target-actual comparison?
• Modification of an existing network: Is a structured implementation plan for network migration drawn up based on differences between network concept and network condition?