Avoiding costly network design errors

19.09.2006
In my previous article I related a story of a network administrator who made several costly mistakes designing and installing a network for a new building. While fictional, most of those examples (and many others) have happened to me on one project or another, but fortunately never all in one project.

Often, network administrators are more focused on routes, packets and other granular network details but miss the bigger picture. While no project ever goes 100 percent smoothly, here are some tips to help avoid some common errors:

1. Create company network standards

As a network administrator, you need a physical infrastructure installed that meets your specifications upon which to build a functional network. Note that sometimes a network administrator's responsibility is not limited to the packet network, as in the previous article the communications department was also responsible for designing and managing the fiber-optic cable plant.

"Infrastructure" refers to much more than the cable plant. You need proper power receptacles, equipment racks, conduits, cable trays, HVAC, physical space ... the list goes on and on. You can increase the chance of getting what you need by creating two documents that serve as your network construction project standards.

The first document is a compilation of your company's network standards in the Construction Specifications Institute format. The MasterFormat 2004 Edition is a construction manual standard used extensively in the construction industry. It covers everything from types of ceiling tiles to plumbing to communications. Specifically, Division 27000 is where network related requirements are placed.

By providing a properly formatted and complete Division 27000 document to the architect at the beginning of a project, the architect, contractor, and subcontractors have the resource to know and understand the infrastructure you require. Furthermore, it gives you the ammunition to ensure that any changes are made at the contractor's expense, not your company's.

For example, if the project's construction manual in the previous article included the requirement that all buildings must have two four inch conduit stubbed out ten feet from the building and the contractor missed that, it would be the contractor's financial responsibility to fix the problem. Note that while you can provide in writing your requirements, there is no guarantee the contractor will read them, but at least your company will not be liable for the additional cost.

Until recently communication cabling requirements were included as a subset of Division 16000, and many architects still go by that standard. Division 16000 was not adequate to include the extensive requirements for the packet communication infrastructure. Several years earlier, there was a movement to create a new division for communications dubbed Division 17000; this morphed into today's Division 27000.

The second document is directed at the architect, not the general contractor. The idea here is to provide to the architect as much information as possible about the workings of the communications department, so the architect has a better understanding of which department in your company handles what aspects of the communication infrastructure. This is a particularly valuable tool for large organizations.

Think of the second document as a sort of design guideline. Some things to include would be which department at your organization is responsible for the conduit infrastructure, contact information, and other design considerations. Remember, the network organization is also a tenant in this building, requiring specific spaces and such; this document helps to convey to the architect what the network group needs.

Finally, I suggest you never refer to your communication space as a closet. While there are standards that dictate how large a Distribution Frame should be based on the projected service area, it is my experience that if you ask an architect for a closet, you get a closet. Ask for a room, and you'll get a room.

2. Communicate openly and frequently with all involved

It should be clear that it is simply not enough to query the end users what their network requirements are when designing a network. Yes, it is important to know this to determine the type of equipment to be placed in each Distribution Frame, but it is also important to look at what is needed by you as the network administrator.

Assuming that a router with ample capacity during the project's design phase will have the same capacity at project completion 18 months later is playing with fire. Work with the core network group to identify and reserve the interface at the beginning of the planning process, or, if you also administer the core, do it yourself. Requesting funds for additional equipment late in the project is at least eMBarrassing and usually much worse.

Find out everything that will run on your network. RemeMBer that "network" may not refer to only the data network itself, depending on your particular situation. VOIP and fire alarm services are examples of services you may need to factor into your design.

3. Factor in contingencies

I have never experienced a new construction project where the network requirements did not change from the initial design meeting. Usually the requirements increase, with an associated cost increase. Therefore cost contingencies as a percentage of the estimate should be added to every estimate provided.

Often during the planning process, new estimates are required as the design of the new facility evolves. This process may involve an initial phase where the architect gathers information for designing the facility, a design review phase, and a construction document review phase just prior to bid. The cost contingency should decrease at each phase (say, 15 percent, 10 percent, 5 percent) but should still be included.

Contingencies are not limited to cost. Contingency planning is also necessary when estimating network equipment and cabling capacity. Make sure you have extra Ethernet ports and fiber circuits available.

4. Invoke an RCDD

Many architectural firms do not employ a Registered Communications Distribution Designer (RCDD). You as a network administrator may hold several certifications but this is probably not one of them. A cabling subcontractor most probably has at least one RCDD on staff.

Discovering near the end of construction that a cable tray planned for a specific hallway cannot be installed because of a new HVAC system is blocking the path can be disastrous. This happened to me some time ago, and the result was that some planned Cat 5E cable runs exceeded 100 meters, necessitating the rapid creation of a new IDF at the end of the project.

Ideally, the RCDD will be able to review all building systems as designed by the architect to ensure such problems do not occur. I recommend that part of your design document that you require an RCDD sign off on all architectural plans. Remember, the goal is to reduce changes after construction has started. A not so exact rule of thumb is that the cost for changes increases exponentially as the project progresses to completion.

5. Remember, honesty is the best policy

Finally, while hopefully the above suggestions will reduce the chance for errors on your estimates, mistakes sometimes happen. The worst thing to do is to try to hide the mistake.

A few years ago a colleague related a story to me where the main ERP system crashed. RAID was employed but there were multiple hard disk failures. The system administrator spent several hours trying to restore the data from the disks but after a few hours called the supervisor to report the problem. The supervisor directed the system administrator to restore from backup tapes.

"Uh, I can't do that" was the reply.

"Why not?"

"The backups hadn't worked in a few months".

"Why didn't you tell me that before?"

"I was afraid of your reaction".

Fortunately a data recovery service was able to restore most of the data. However, it cost tens of thousands of dollars...and the system administrator's job.

Summary

There is no way to accurately predict the exact cost of a new network. However, employing the above suggestions will reduce the chance that you will be bitten by costly overruns.

Greg Schaffer is the Director of Network Services at Middle Tennessee State University. He has over 15 years of experience in networking, primarily in higher education. He can be reached at newtnoise@comcast.net.