Structured copper cabling standards specify generic installation and design topologies for twisted-pair media that are characterized by a “category” or “class” of transmission performance and deployed in the data center. These cabling standards are subsequently referenced in applications standards as the minimum level of performance to ensure application operation. There are many advantages to specifying standards-compliant cabling. These include the assurance of applications operation, the flexibility of backward compatibility and interoperability, and a structured topology universally recognized by professionals responsible for managing cabling.
Two organizations, the Telecommunications Industry Association (TIA) and the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) develop structured cabling standards. Committee members work alongside applications development groups to ensure that new grades of cabling will support the latest signal transmission technologies. TIA standards are typically specified by North American end-users, while ISO/IEC standards are commonly specified in international markets.
While the technical requirements of TIA and ISO/IEC are very similar for various grades of cabling, differences in terminology can cause confusion. TIA standards for cabling components (e.g., cables, connecting hardware, and patch cords) are characterized by a performance category and are mated to form a permanent link or channel that is also described by a performance category.
ISO/IEC standards characterize components by performance category, and permanent links and channels are described by a performance class. TIA and ISO/IEC equivalent grades of performance are characterized by bandwidth as shown in table 1.
Category 5e/class D, category 6/class E, and category 6A/class EA media are available in unshielded twisted-pair (UTP) and shielded twisted-pair (F/UTP) constructions. Class F and class FA media are supported by fully-shielded twisted-pair (S/FTP) constructions. Siemon recommends the use of shielded and fully shielded systems in the data center to ensure the highest levels of signal immunity and performance margin.
Whether upgrading an existing or developing a new data center, it is critical to look to the standards for guidance on performance and lifecycle. Both TIA and ISO/IEC state that cabling systems are intended to have a useful life in excess of 10 years. Since applications, such as ethernet, typically have a useful life of five years, cabling should support two generations of network applications. For most data centers, this means specifying a cabling plant capable of supporting 1000 BASE-T (gigabit ethernet) today and an upgrade to 10G BASE-T in five years.
TIA categories and ISO/IEC classes of structured cabling recognized for support of applications in the data center are specified in table 2.