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Site Address, Contact, and Access List. This list includes the company shipping address, site contact to receive shipments, and site contacts for work being done. The list should also include the site access procedures (i.e., normal and after-hours) and who arranges facilities (i.e., power, floor space) for the project.
Trunk Circuit Lists. This list details all the circuits used to interconnect sites. It should include LEC and IXC circuit numbers and service and support phone numbers. All new circuits and those to be disconnected should be marked clearly. A typical format is:
From/To/Ckt ID-IXC/LEC(From)/LEC(To)/Framing/Type
Port Circuit Lists. This is a detailed listing of all the current port-level circuits used within the network. This information should then have an addendum document that shows the circuits being disconnected, those being moved, and the new circuits being added to the new network. A typical data format is:
From (Node/Shelf/Card/Port)/
To (Node/Shelf/Card/Port)/Type/Speed/DTE-DCE/Clocking
A typical voice format is:
From (PBX/Card/DS0s)(Node/Shelf/Card/Port)/
To (PBX/Card/DS0s) (Node/Shelf/Card/Port)/Framing/Trunk Group/Clocking
Drawings. Network drawings for documentation purposes should include the current topology and the future topology. The block diagram of the current system should be an overview of the entire network including site IDs and intrasite trunks. The block diagram of the future topology should be an overview of the entire new network including site IDs and only the intrasite trunks that will remain after the conversion.
Individual Site Drawing. This diagram should be an overview of one site in the new network including the intrasite trunks and equipment installed at the site. It should not show port-level detail. It should show dial-up access with phone numbers and a patch panel with the designations.
Once the network information is gathered and processed, it must be applied. The goal is to deploy the new network equipment with as little downtime as possible. There are a variety of methods for completing a conversion.
The easiest way to convert to a new WAN is to install the new multiplexing equipment and interconnect it with new trunk (i.e., FT1, T1, and T3) facilities. This is the most costly method of conversion. For example, if it takes six months to complete the conversion, and there are 47 T1s in the current network and 35 planned for the new network, that is 82 T1s for the duration of the conversion. The corporate budget has just taken a big blow with little real return on investment.
To find a balance between cost and benefit, the first question to research is whether there are regions of connectivity within the companys network. For example, a corporation has four regional main offices in Atlanta, Chicago, Dallas, and New York, and headquarters in Washington, D.C. Within these regions, all connectivity terminates at the main region office. Only main offices and headquarters need interconnectivity. It is easy to see that a conversion of each region could be completed first, then the connectivity could be converted between the main offices and the headquarters location.
Most corporate networks have some percentage of traffic going to a variety of locations such as headquarters and regional sites. This information should be available in the current network connectivity map, which should indicate the sites supporting the heaviest concentrations of traffic. This allows the network designer to construct a plan that rolls through a series of sites.
First, a few new trunk facilities should be ordered and activated. By activating a few links between the headquarters and several sites, part of the traffic back to headquarters can be migrated. The emptied connections should be deleted from the old network once the traffic is migrated. The load on the old network has been lightened and some trunks can now be removed. Any trunk facilities that can be emptied should be removed and those that are designated to be reused in the new network should be added. Orders to disconnect unused trunks can also be issued 30 days after that.
In most network conversions, this leapfrog approach can be used quite effectively. It allows network managers to find any flaws in the conversion and correct them before the rest of the process continues.
Cables are the most overlooked source of problems in large-scale conversions. For example, one company had 23 different cables in its old network. Because the new multiplexer they had selected could perform software-based lead mapping, the number of cables could be reduced to five. That type of change is an excellent benefit.
During the physical audit, the physical data on the cables should be checked. This is the time to determine if old cables can be reused or if new ones must be ordered. If the new equipment vendor has assigned a program manager to the installation, that persons expertise should be used.
The cable information should be checked in a lab environment if possible. Otherwise, the nearest site supporting the most widely used port types should be used to verify cable pinouts. The most important thing to remember is that changes to cables can take weeks, not including the time it can take to determine the pinout is wrong and what the appropriate changes should be.
Site preparation is an important part of the migration strategy. One company found that its paperwork was the bottleneck in getting equipment from one of the vendors. A minor change in the process cut the turnaround time from six weeks to less than four weeks. It takes time for the internal paperwork to be completed, but it is always necessary to get floor space, electric service, telephone company access, and dial-up access to the multiplexer installed or prepared. Shipping time should also be factored into the schedule.
A modem and telephone line should be installed with each device. With todays intelligent multiplexers, a node can be installed before the trunk facilities are available and activated remotely via the dial-up port. This type of preparedness will also be important in the event that all facilities to a site are lost at the same time. A dial-back type modem is preferable. A basic password-protected modem should be used if the system does not have security features. The passwords should be changed monthly or quarterly as well as upon the termination of any employee who had access to the network.
To ensure a successful conversion, it is helpful to send staff members to training shortly before the actual installations start. Then they will be able to fully participate in the conversions using their new knowledge. Network managers with well-trained staffs should have no problem achieving a relatively smooth conversion using the guidelines provided in this chapter. A deployment can be done in a timely manner with minimum disruptions to service within the company.
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