White Paper Fiber Backbone Cabling in Buildings www.commscope.com
Contents Introduction 3 Backbone Cabling Speeds 3 Optical Fiber in the Backbone 4 b/s Optical Fiber Backbone 4 Migrating to 40 Gbps and 100 Gbps 5 Backbone Distances 7 Existing Installations and support for 40Gbps and 100Gbps 8 New Installations and support for 40Gbps and 100Gbps 9 Conclusion 9 www.commscope.com 2
Introduction Until recently, the horizontal cabling in most buildings was designed to support speeds up to 1 Gbps to the desk, and 1000BASE-T was considered ample bandwidth for horizontal applications in Enterprise buildings. Today, however, developments in wireless technologies are pushing the horizontal bandwidth beyond 1 Gbps, and the broad adoption of these technologies will have a significant impact towards adoption of faster speeds elsewhere in the horizontal and backbone network. The newest generation of IEEE 802.11ac Wi-Fi Access Points is capable of supporting wireless speeds up to 6.9 Gbps. In order to provide sufficient backhaul bandwidth for these devices and in a clear indication that 1 Gbps speeds are no longer sufficient the IEEE is currently in the process of defining 2.5 Gbps and 5 Gbps Ethernet interfaces (2.5GBASE-T and 5GBASE-T). The first commercial implementations of these new interfaces are designed to auto-negotiate up to 10 Gbps (BASE-T) if supported by the cabling. Additionally, leading-edge In-Building Wireless systems are already in the market, with horizontal connectivity based on BASE-T technology. As these technologies become more widely deployed, the aggregate effects of user bandwidth are expected to drive even higher speeds in network backbones. As a result, the bandwidth requirements for building backbones designed to support these applications will shift from 10 Gbps to 40 Gbps and eventually to 100 Gbps. Backbone Cabling Speeds As a practical approach, backbones have traditionally been designed to exceed the horizontal requirements by a factor of 10. For example, 1 Gbps backbones were designed to support 100Mb/s horizontal requirements, and 10 Gbps backbones are currently being designed to support up to 1 Gbps horizontal requirements. As speeds in the horizontal migrate to 2.5 Gbps, 5 Gbps, or 10 Gbps, the backbone must be designed to support bandwidth beyond 10 Gbps. It is therefore recommended that new buildings or retrofits deploy a backbone that is capable of supporting speeds of 40 Gbps and/or 100 Gbps. Enterprise Switch 40G/100G OM1/2 LAN Switch OM3/4 xn OM3 LAN Switch LAN Switch Cat 5e 100M 100M 100M 100M 100M Cat 6 2.5/5/ Cat 6A 2.5/5/ 2.5/5/ 2.5/5/ 2.5/5/ 1995 Figure 1. Enterprise LAN Cabling Timeline 2005 > 2015 www.commscope.com 3
Optical Fiber in the Backbone Backbone cabling provides interconnections between access provider (AP) space, entrance facilities (EFs), equipment rooms (ERs), telecommunication rooms (TRs), and telecommunication enclosures (TEs) (See Figure 2). ANSI/TIA-568.3-D recommends deploying a hierarchical star topology for the backbone, with no more than two levels of cross-connections. For the simplest design, the main crossconnect (MC) in the ER feeds directly to the horizontal cross-connect (HC) in the TR on each floor (see Figure 2). Optional intermediate cross-connects (IC) may be positioned between the MC and HC. horizontal Category 6A recommended Telecommunication room (HC) 40G or 100G backbone OM4 recommended Equipment Room (MC) Figure 2. Building Backbone Cabling System The standard recognized transmission media for backbone cabling comprise multimode and singlemode fiber. Laser-optimized 50/125µm (OM3 and OM4) multimode fiber is recommended and is typically installed for 10 Gbps building backbones up to 300 meters and 550 meters, respectively, based on the lower electronics costs when compared with singlemode fiber. Singlemode fiber is typically installed where the channel lengths are expected to exceed the capabilities of multimode fiber when exceeding the OM4 support distance for 550 m for 10 Gbps. b/s Optical Fiber Backbone 10 Gbps backbones utilize serial transmission with standard two-fiber duplex cabling, in which one fiber transmits and one fiber receives. A 10 Gbps channel typically consists of backbone cables terminated (or spliced) to LC connectors. Duplex LC patch cords are, in turn, used to connect the backbone cabling to active networking equipment, as shown in Figure 3. www.commscope.com 4
LC distribution module Switching equipment Backbone cable Second Floor Duplex LC patch cords Switching equipment First Floor Switching equipment Ground Floor Figure 3. 10 Gbps fiber backbone channel Migrating to 40 Gbps and 100 Gbps Unlike 10 Gbps backbones, which utilize serial transmission, current 40 Gbps and 100 Gbps multimode applications utilize a parallel transmission scheme. 40GBASE-SR4 requires eight fibers, in which four transmit and four receive at 10 Gbps each lane, and 100GBASE-SR4 requires eight fibers, in which four transmit and four receive at 25 Gbps each lane (Figure 4). In contrast to 10 Gbps backbones, multimode backbone channels capable of supporting 40GBASE-SR4 and 100GBASE-SR4 are typically deployed with preterminated MPO trunks, MPO pass-through panels, and MPO cords (Figure 5). www.commscope.com 5
Tx Tx Tx Tx Rx Rx Rx Rx Tx Tx Tx Tx Rx Rx Rx Rx b/s Per Lane b/s Per Lane 25Gb/s Per Lane 25Gb/s Per Lane 40GBASE-SR4 100GBASE-SR4 Figure 4. 40GBASE-SR4 and 100GBASE-SR4 transmission schemes 40/100G switch MPO cord Second Floor 12-fiber trunk 40/100G switch First Floor 40/100G switch Ground Floor Figure 5. 40GBASE-SR4 and 100GBASE-SR4 channel www.commscope.com 6
When migrating from 40GbE to 100GbE, 100GBASE-SR4 is recommended, as it utilizes the same 8 fiber transmission scheme as 40GBASE-SR4 therefore providing minimal network interruption and the most seamless upgrade. As Figure 8 illustrates, by utilizing preterminated trunk cables in the initial 10 Gbps deployment, it is possible to seamlessly migrate from 10 Gbps to 40 Gbps and 100 Gbps speeds by repurposing the trunk cables and replacing the equipment or patch cords and distribution modules. Existing Channels using MPO trunk cabling 12 duplex cords 12 duplex cords 12 duplex cords 12f each 12 duplex cords 12f each Migration to 40GBASE-SR4 or 100GBASE-SR4 12f each 12f each 12f each 12f each 12f each 12f each Figure 6. Migration from 10 Gbps to 100 Gbps 24f 24f Backbone 12f Distances each 12f 12f 12f 12f each 12f 24f The IEEE 802.3ba standard defines the capabilities of OM3 24f and OM4 fiber to support 12f 40G and 100G Ethernet applications (Table 12f 1). While BASE-SR has a reach of 400 12fmeters over OM4, commercially available 12f 40G and 100G systems are currently limited to 150 meters or 100 meters in the case of 100GBASE-SR4. However, with extended-reach VCSELs, it is possible to reach 400 meters with 40 Gbps, facilitating a seamless migration from to 40G. It is expected that similar extended-reach VCSELs will be available for 100G as the market develops, but in situations where distances beyond 150 meters are expected installing singlemode fiber alongside multimode will ensure that the backbone is able to accommodate speeds in excess of 40 Gbps. www.commscope.com 7
Backbone application BASE-SR (850 nm) BASE-LRM (1300 nm) 40GBASE-SR4 100GBASE-SR4 100GBASE-SR10 Standard specified max. distance OM3 CommScope supported distance Standard specified max. distance 300 meters (984 feet) 300 meters (980 feet) 400 meters (1312 feet) OM4 CommScope supported distance 2-Conn 550 meters (1800 feet) 4-Conn 530 meters (1740 feet 220 meters (720 feet) 220 meters (720 feet) 220 meters (720 feet) 220 meters (720 feet) 100 meters (328 feet) 70 meters 100 meters (328 feet) 2-Conn 135 meters (440 feet) 4-Conn 125 meters (410 feet) 2-Conn 85 meters (280 feet) 4-Conn 80 meters (260 feet) 2-Conn 135 meters (440 feet) 4-Conn 125 meters (410 feet) 150 meters (492 feet) 100 meters 150 meters (492 feet) 2-Conn 170 meters (560 feet) 2-Conn 170 meters (560 feet) 2-Conn 120 meters (390 feet) 4-Conn 80 meters (260 feet) 2-Conn 170 meters (560 feet) 4-Conn 155 meters (510 feet) Table 1. Multimode fiber backbone cabling distances for 10 Gbps, 40 Gbps, and 100 Gbps applications Note 1: Standard distances are based on two connections. For channels with more connections, please refer to SYSTIMAX Applications Performance Specifications, Volume One. Note 2: CommScope supported distance is applicable to installations eligible for registration for the CommScope 20 Year Extended Product Warranty and Applications Assurance Existing Installations and support for 40Gbps and 100Gbps Support of 40Gbps and 100Gbps over existing multimode backbones may be accomplished with the use of an LC to MPO fanout to connect the existing LC connectors in the installed cabling to the MPO connector in the 40 Gbps or 100 Gbps equipment. As shown in Figure 7, the LC cord ends connect with the LC couplers in the shelf, while the MPO connector is inserted into the 40G or 100G transceiver. As the transceivers are always pinned, a fanout cord with an unpinned MPO connector is used. Consult Table 1 for maximum distances supported, depending on the type of installed optical fiber. LC distribution module 40/100G switch Figure 7. 40/100G switch connection with Array Cord www.commscope.com 8
Fiber management becomes more complex with this option, as the individual LCs must be mapped to align with the transmission schemes outlined in Figure 4. This can become a significant challenge at the equipment room where multiple 40/100G links will be terminated and connected to equipment. New Installations and support for 40Gbps and 100Gbps For new installations, the use of pre-terminated MPO trunks offers faster installation speeds, factory-assembled performance, easier administration, and higher panel/shelf density. As shown in Figure 5, when the building backbone is deployed with preterminated MPO trunks, MPO patch cords are used to connect the MPO connectors in the installed cabling to the MPO connectors in the 40 Gbps or 100 Gbps equipment. As the transceivers and panel ports are always pinned, MPO cords with unpinned MPO connectors are used. OM3 fiber is the minimum recommendation, with OM4 fiber strongly recommended to allow for added distance and/or connector pairs in a link. Consult Table 1 for maximum distances supported, depending on the optical fiber type and number of connectors. When installing preterminated cabling in the buildings, care must be taken to ensure that the risk of damage to the preterminated ends is minimized during installation. Installing MPObased preterminated fiber cabling in the riser is relatively easy if sufficient space has been allocated and the IDFs on each floor are all located in line vertically. However, in cases where the IDFs are not aligned and/or sufficient space is not available in pathways, a conventional approach as described for existing installations may be appropriate. The use of pulling socks is strongly recommended when installing preterminated cabling to protect the pre-terminated ends. Re-useable pulling socks can be ordered to help ensure that the MPO connectors are not damaged during installation. The use of preterminated cabling simplifies fiber management, with MPO to MPO connectivity throughout, and increases panel density. This can be a significant benefit at the equipment room where multiple 40/100G links will be terminated and connected to equipment. Conclusion With continued growth in data rates in the horizontal driven by applications such as 802.11ac and In-Building Wireless, the backbone should be designed to accommodate speeds of 40 Gbps or 100 Gbps. Planning for a seamless migration path ensures that the backbone will be able to support high-capacity wireless and other high-bandwidth applications that may emerge. Installing the proper cabling today will extend the expected life of the structured cabling and reduce upgrade costs over time. www.commscope.com 9
CommScope (NASDAQ: COMM) helps companies around the world design, build and manage their wired and wireless networks. Our network infrastructure solutions help customers increase bandwidth; maximize existing capacity; improve network performance and availability; increase energy efficiency; and simplify technology migration. You will find our solutions in the largest buildings, venues and outdoor spaces; in data centers and buildings of all shapes, sizes and complexity; at wireless cell sites and in cable headends; and in airports, trains, and tunnels. Vital networks around the world run on CommScope solutions. www.commscope.com Visit our website or contact your local CommScope representative for more information. 2015 CommScope, Inc. All rights reserved. All trademarks identified by or are registered trademarks or trademarks, respectively, of CommScope, Inc. This document is for planning purposes only and is not intended to modify or supplement any specifications or warranties relating to CommScope products or services. CommScope is certified according to ISO 9001, TL 9000, and ISO 14001. WP-109423-EN (07/15)