1 Overview
As is well known, structured cabling is a general term encompassing several types of cabling, including the last 100 meters of cabling for building LANs, the last 2 kilometers of cabling for integrated campus (community) networks, and internal cabling for computer data center server rooms. The allowable length of cabling in different locations should be calculated based on its purpose and corresponding transmission specifications. Regardless of its location, structured cabling is an extension and important component of the urban telecommunications network. Only by deeply understanding the development trends of the urban telecommunications network can we accurately grasp how structured cabling should be designed; and only by adopting a strategy of developing in sync with the urban telecommunications network and adapting to it can structured cabling truly realize the overall benefits of the network and achieve a win-win economic outcome. The following discussion will focus on the development of the telecommunications network, the need for structured cabling to develop in sync with it, and the latest advancements in structured cabling products.
2. Development Trends of Telecommunication Networks
Traditional telecommunications networks primarily focused on voice communication, with a small amount of low-speed point-to-point data communication such as Digital Data Network (DDN) and Frame Relay (FR), initially limited to a single voice channel bandwidth of less than 64kbps. In the early 1990s, drawing on international experience, my country introduced network communication technologies such as structured cabling and Ethernet, and formulated corresponding standards and specifications, actively promoting their application, leading to significant progress in telecommunications networks. In just over a decade, network communication technology has evolved from 10 Mbps, 100 Mbps, and gigabit speeds to 10 Gigabit speeds, and even 100 Gigabit networks are about to be deployed on a large scale.
The development of telecommunications networks is comprehensive, encompassing communication methods such as wired, wireless, and satellite; and communication content including telephone, television, and data. These can be further subdivided into many categories, resulting in a multitude of methods and complex content. To stay focused on the topic, this article will only discuss content related to structured cabling.
2.1 Rapid Development of Passive Optical Networks (PON)
Currently, Passive Optical Networks (PONs) are developing rapidly in my country. Applications such as EPON (Ethernet Passive Optical Network), GPON (Gigabit Passive Optical Network), GEPON (Gigabit Ethernet Passive Optical Network), APON (ATM Passive Optical Network), and BPON (Broadband Passive Optical Network) will directly impact structured cabling. The following example illustrates EPON/GPON networking:
EPON/GPON mainly consists of OLT (Optical Line Terminal) central office equipment, ODN (Optical Distribution Network) handover equipment, and ONU (Optical Network Unit) user terminal equipment. A schematic diagram of the EPON/GPON network topology is shown in Figure 1.
Network characteristics of EPON/GPON:
● In addition to optical interfaces, OLT and ONU can be equipped with GE (Gigabit Ethernet), FE (Fiber Ethernet), RF (Radio Frequency), E1 (2.048Mbps) interfaces to enable various network applications.
●EPON can provide symmetrical uplink and downlink speeds of 1.25Gbps.
●GPON can provide uplink speeds of 155Mbps, 622Mbps, 1.24Gbps or 2.48Gbps; and downlink speeds of 1.24Gbps or 2.48Gbps.
● The public IP network signal uses wavelength division multiplexing (WDM) technology, injecting the uplink 1490nm and downlink 1310nm signals into the same optical fiber via the central office OLT integrated transceiver. These signals are then branched into 32.64 or 128 optical links to the corresponding ONUs via the optical distribution network (ODN). If necessary, the CATV signal can also be injected into the central office OLT integrated transceiver using a third wavelength of 1550nm, separated at the corresponding user-end ONU integrated transceiver, and then distributed to the user's cable TV distribution network via the RF interface.
●EPON/GPON networks support tree, star, bus, hybrid, and redundant topologies.
●EPON is based on Ethernet technology and the IEEE P802.3ah standard. When transmitting a 1.25Gbps data stream, the transmission distance between the optical line terminal (OLT) and the optical network terminal (ONU) can reach about 20km.
●GPON is based on ITU-T standards such as G984.1 to G984.5 and is the preferred FTTH (Fiber to the Home) technology in Europe and North America, and is being adopted globally. GPON's universal framing protocol provides an open interface that offers transmission efficiency for multiple protocols, with symmetrical and asymmetrical transmission capabilities at a rate of 2.48Gbps, and a transmission distance of up to 37km between the OLT and ONU.
2.2 FTTH (Fiber to the Home) or FTTB/N (Fiber to the Building/Community Node)
As EPON/GPON technology matures, fiber optic cables are becoming increasingly cheaper. The possibility of extending fiber optic cables to buildings, community nodes, and even homes is growing. Telecommunications operators naturally need to consider the return on investment, with the ultimate goal of recovering costs and making a profit in the short term. Many telecommunications operators have conducted comprehensive comparisons of proposed solutions for FTTH and FTTB/N, and generally believe that:
Features of FTTH (Fiber to the Home) solutions:
advantage:
1) Provides a large bandwidth capacity, suitable for high-speed network applications.
2) It is not affected by external electromagnetic interference, has good anti-interference performance, and high communication quality.
3) Silica, the material used to produce optical fibers, is inexhaustible.
4) Currently, the price of optical fiber cables is lower than that of copper cables (but the price of photoelectric conversion equipment is still relatively high, so the overall cost is still relatively high).
shortcoming:
1) For projects of the same scale, the initial investment is higher.
2) Many new optical cables are being built, and the construction period is relatively long (compared to the FTTB/N solution).
3) The return on investment is relatively slow.
Features of the FTTB/N (Fiber to the Building/Community Node, existing copper cable to the home, adding VDSLZ equipment) solution:
advantage:
1) It provides good broadband capacity and is suitable for general network applications.
2) The initial investment for projects of the same scale is less, approximately 21% to 34% of that for FTTH solutions (the photoelectric conversion on the backbone side can save a significant amount of photoelectric conversion costs on the user side, and the use of existing copper cables can also save costs).
3) The construction period is shorter by utilizing existing copper cables.
4) The return on investment is relatively fast.
shortcoming:
1) It is susceptible to external electromagnetic interference. If protective measures are taken, additional investment is required.
2) Copper is a strategic material and its use is controlled.
Given the comparison above, FTTH and FTTB/N each have their own characteristics, and the appropriate construction plan will be selected based on the actual conditions of each region. For example, newly built communities may choose FTTH, while existing communities are more likely to choose FTTB/N. Therefore, when designing structured cabling, it is essential to have a thorough understanding of the local telecommunications environment and select a suitable structured cabling construction plan.
2.3 Illustrate FTTH construction plans with examples
Starting in April 2005, Wuhan Telecom launched the commercial application of FTTH in Zisong Garden, and subsequently built integrated application networks in communities such as Wuhan Entrepreneurship Street and Wuhan Contemporary International Garden.
Figure 2 shows a schematic diagram of the FTTH network topology built by Wuhan Telecom.
In the picture:
FE/GE—Fiber Ethernet/Gigabit Ethernet
PSTN/NGN — Telephone Switching Transmission Network/Next Generation Network
POTS—Telephone Line
E1—2.048Mbps interface
The features of the FTTH network recommended by Wuhan Telecom:
● The community features a unified network, providing telephone, IP (including IPTV), and CATV services simultaneously. While technologically advanced and economically sound, this integration presents some management challenges. For instance, CATV is regulated by the State Administration of Radio, Film and Television, while FTTH is managed by telecommunications authorities. Effective coordination between these two departments is crucial for achieving a win-win situation.
●Using domestically produced equipment from Wuhan Fiberhome Communications has a price advantage.
The central office unit, model EPONOLTAN5116-02, is placed in the central office equipment room.
The user terminal unit, model ONUAN5006-04, is placed inside the smart terminal box in the user's home.
The optical splitter is placed inside the optical junction box.
3. The design of structured cabling should be adapted to the development of telecommunications networks.
As shown above, telecommunications networks can be FTTH or FTTB/N, and the specifics vary from place to place. Similarly, structured cabling can be the last 100 meters of a building, the last 2 kilometers of a campus/community, or cabling within a data center; each project will have its own specific requirements. The typical structured cabling design concepts are explained below:
3.1 Design of the last 100m of structured cabling for building LAN
If the surrounding telecommunications network has implemented FTTB (Fiber to the Building), the building's local area network (LAN) should generally adopt a copper-cable-based design. However, this doesn't preclude some users from using fiber-to-the-desktop cabling to meet their needs for higher speeds and security. If the surrounding telecommunications network hasn't yet implemented FTTB, it's important to understand if there are any recent expansion plans. If there are plans and the construction schedule can be met, the design can still be considered according to the planned progress; if there are no plans, the current state of the telecommunications network should be used as a basis for considering the building's integrated cabling solution, while allowing for appropriate future expansion.
3.2 Integrated cabling design for the last 2km of the integrated network in the park (community)
If FTTN (Fiber to the Park or Community Node) has been implemented in the surrounding telecommunications network, then a backbone fiber optic cable should be used to extend to the wiring closets on each floor within the park (community). Floor wiring should primarily use copper cables, with fiber optic extensions to the desktops for some important users also possible. If FTTH has not yet been implemented by the telecommunications department, solutions should be compared based on the size of the park (community). Larger-scale parks should primarily use a backbone fiber optic cable; smaller-scale parks can use a combination of fiber optic and copper cables. Fiber optic cables should be used for long distances, while copper cables can be used for short distances. Floor wiring should generally use copper cables, with a small number of fiber optic extensions to the desktops possible. The connection between the park (community) and the telecommunications network should use a fiber optic cable design.
3.3 Integrated cabling in data center computer room
Structured cabling in data center server rooms is primarily used for cabling between network devices such as routers, switches, and servers, as well as between distribution equipment. It serves as a crucial connection medium between these devices. Different devices have different requirements, and appropriate cables should be selected based on the volume of information traffic to ensure optimal network operation, preventing network stagnation due to localized congestion and avoiding waste caused by overloading the network with cables that are not properly configured.
Generally, UTP copper cabling should be the preferred solution. Current products support speeds up to 10Gbps, and 100Gbps products are about to be widely deployed, which can fully meet network needs. If there are sources of electromagnetic interference around the data center, appropriate protective measures should be taken. In cases of severe interference, fiber optic cabling should be used. If the data center is shielded, UTP copper cabling can still be used inside the data center, but the cables leading out of and into the data center should be fiber optic cabling, and an optical/copper medium conversion module should be installed.
The connection between the data center and the telecommunications network should be selected and decided based on the current status and development of the telecommunications network. The design is similar to the last 2km of integrated cabling for the park (community) integrated network in the previous section, and will not be repeated here.
4. Latest Developments in Structured Cabling Products
In addition to understanding the development of telecommunications networks, structural cabling designers should also keep abreast of the latest advancements in structural cabling products. This is another important factor in ensuring that the design is practical.
Belden's U/UTP unshielded cable adopts a "king" shaped cross-section cable structure; the IDC module adopts measures such as 90° turn-end between wire pairs, spring-loaded crossover of the wire pairs, and the addition of compensation circuits, which can support Category 7 standard applications at 625MHz (Category 7 standard is 600MHz).
Corning's aluminum foil shielded wire-pair shielded cables with copper mesh sheaths and wire-pair shielded wiring modules can support higher standards. For example:
The S/FTP1200/22 cable (22 AGW core, equivalent to 0.6438 mm) can support 1200 MHz, which is twice as high as the Category 7 standard 600 MHz.
S/FTP800/23 cable (23 AGW core, equivalent to 0.5733 mm) can support 800 MHz, which is higher than Category 7 standard.
The S/FTP450/23 cable (with aluminum foil sheath and 23 AGW core wire, equivalent to 0.5733 mm) can support 450MHz, which is higher than the Category 6 standard of 250MHz and lower than the Category 7 standard of 600MHz.
Corning also offers plug-and-play optical/copper media conversion modules that can be directly used for media conversion solutions between fiber optic and copper Gigabit Ethernet.
Nexans' LANmark-7cat.7S/FTP4 Category 7 fully shielded twisted-pair cable (23 AGW core, equivalent to 0.5733) can support 1000MHz, higher than the Category 7 standard of 600MHz, offering significant redundancy and development potential. If used for CATV cable television transmission, it can support 1000MHz, covering all television channels, and has further expansion potential.
The LANmark-610GF1/UTP4 supports 500MHz for Category 6e 10G shielded twisted-pair cable (23AGW core, equivalent to 0.5733mm), which is close to the Category 7 standard of 600MHz, and supports 10G Ethernet applications in IEEE 802.3an draft version 2.3.
The LANmark-OF fiber optic cable series can support a variety of applications, such as:
According to optical cable structure:
Indoor tight buffer layer standard TB optical cable, suitable for horizontal and vertical shafts.
Outdoor loose-tube armored standard UC optical cable, suitable for direct burial and conduit installation.
UG fiber optic cable, suitable for both indoor and outdoor use in open pipes, horizontal and vertical shafts and ducts.
Indoor reinforced TBW+ fiber optic cable with tight buffer layer, suitable for both horizontal and vertical shafts.
Indoor/outdoor loose-tube reinforced UG+ optical cable, suitable for horizontal, vertical shafts and ducts.
When using single-mode fiber with the OSI 9/125μm application protocol at 10Gbit/s, the transmission distance at a wavelength of 1310nm is 10km; the transmission distance at a wavelength of 1550nm is 40km. When using G652D zero-water-peak single-mode fiber with the 9/125μm application protocol at 10Gbit/s, the attenuation values are: ≤0.35dB/km (1310nm), ≤0.28dB/km (1383nm), ≤0.21dB/km (1550nm), and ≤0.22dB/km (1625nm). The cutoff wavelength is 1180～1330nm.
CommScope's SYSTIMAX GigaSPEEDX10D supports speeds of up to 10Gbps on UTP systems, meeting the high bandwidth requirements of core-to-switch backbone connections and horizontal connectivity needs from edge-to-server connections. It also provides redundancy support for Storage Area Network/Network Attached Storage (SAN/NAS) configurations. For data center cabling conditions, the system supports ANEXT performance testing with 6-pack cable per connection point over a 100m channel, demonstrating good performance specifications.
Siemon's CAT6+ cables, whether UTP or FTP, can support 10 Gigabit Ethernet over a distance of 100m. When using fiber optic transmission for 10 Gigabit Ethernet, it is recommended to use 50μm laser-optimized multimode fiber (OM3) to support 300m 10 Gigabit transmission, or 50μm standard multimode fiber (OM2) to support 58m 10 Gigabit transmission. Single-mode fiber is also used in data centers, but the corresponding fiber optic network equipment is more expensive. Recently, the IEEE established a dedicated working group to evaluate the feasibility of transmitting 100Gbps over single-mode fiber. Therefore, considering future development, using some single-mode zero-water-peak fiber in data center cabling is also worthwhile.
Detwell recommends using CAT6, CAT6+, or CAT7 UTP or FTP to guarantee gigabit speeds, with the option to upgrade to 10 gigabit speeds. They also recommend using OM3 10 gigabit multimode fiber (50μm) or OM2 gigabit multimode fiber (50μm), and OSI single-mode zero-water-peak fiber in the main distribution area (MDA). If necessary, products containing different types of fiber cores within the same sheathed cable can also be used.
Due to limited information, a comprehensive product overview is difficult. While this overview may be somewhat incomplete, some examples are provided for reference to illustrate the points. It is hoped that when conducting engineering design, everyone will conduct in-depth research on the product, fully understand the situation, and then make objective evaluations and decisions.
In summary, it is evident that the development speed of structured cabling has surpassed that of network equipment. For example, Corning's copper cabling can support 1200MHz, which is twice as high as the Category 7 standard of 600MHz, but network equipment can only support 10 Gigabit or at most 100 Gigabit.
Currently, the main computer network protocols being used commercially include:
Copper cables: 100 Mbps Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet.
Fiber optic cables: 100 Mbps Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet, and soon...
40 Gigabit and 100 Gigabit Ethernet deployed at scale.
I don't think this situation will last long. Higher-level commercial computer network protocols will emerge, which is not surprising. Only through mutual promotion can the network develop to a higher level. We should have this understanding.
5. Conclusion
The development of telecommunications networks has brought fiber optic cables closer to users, and the carrying capacity of structured cabling and network equipment has been continuously improved. Copper cables can support 10 Gigabit Ethernet, and fiber optic cables can support 100 Gigabit Ethernet. Corresponding Ethernet protocols are also being gradually implemented. This is an inevitable trend in network system development. As an important component of telecommunications networks, structured cabling should adapt to this trend and coordinate with the product advancements of network equipment. The design scheme should meet development needs while remaining realistic and feasible, resulting in an optimized and practical solution.
