Best trends in optical networking

Best trends in optical networking

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  Best Trends inOptical Networking 1. Executive Summary of the development of the25G Standard The ever-increasing demand of diverse multimedia applications and services as well as the re- quirement for bandwidth expansions and faster data rates becomes a challenge for every data center everywhere. Emerging technologies like cloud computing also acted as catalyst in driving the industry to develop a new approach to adopt in these fast-charging trends. Reliance on networking permeates every aspect of our world, and data center bandwidth re- quirements are expanding at double-digit rates-along with an equally urgent push to contain costs. New technologies necessitate that data centers remain flexible and scalable enough to adapt to changing requirements. The rise of cloud providers changed the data center Ethernet landscape, creating a viable market for high-speed, reasonably-priced connectivity. Leading cloud and telco providers are clamoring for even more network performance in order to meet the needs of their web-scale data centers and cloud-based services, without compromis- ing the cost-to-performance ratio. To help address network performance needs, leading man- ufacturers have joined forces to define and drive the 25 Gigabit Ethernet (25GbE) technology. To suffice the increasing demands of collaborative multimedia services and applications, to an- swer to the fast-changing traffic patterns, and to improve accommodations of users’ bandwidth requirement for communication. This is one of the reasons why an industry consortium was formed to create a new Ethernet connectivity standard in data centers. The consortium’s goal is to enable the transmission of Ethernet frames at 25 or 50Gb per second (Gbps) and to promote the standardization and improvement of the interfaces for applicable products. Last July 2014, the IEEE agreed to support the development of this 25GbE standards for servers and switching due to the increasing demand for a much faster network performance while maintaining Ether- net economics. This standard was called 25 Gigabit Ethernet or 25Base-T, developed by the IEEE 802-3 task force P802.3by. This standard was derived from 100GbE, since its operation works with four 25Gbps that are running on four fibers in each direction. The IEEE 802.3by 25GbE standard is technically complete and ratified on June of 2016. 1 www.cbo-it.de
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  2. The Pushfor higher Bandwidth for Mediaand Transceiver Modules The requirements in the market for Ethernet are constantly changing for different applications and the coherent need of speed, further distance and lower costs. Various speeds are also needed for specific applications like Wireless Access Points that use 2.5GbE and 5GbE; servers which need up to 25GbE and lastly core networks which operate with up to 400GbE. Due to this exponentially growing, global bandwidth requirements, Ethernet speeds are also in constant development at a high rate to stay ahead of these demands. However, innovation is occurring within varied application spaces at lower speeds. Most of todays’ servers are still using GbE, and some users do not care for a foreseeable future about higher speeds like Terabit Ethernet (TbE) and 400GbE. There is diversification of efforts to coupe up these requirements, but a common goal will un- dermine the diversities, which is a global requirement for a market-driven standard, fostering innovation and enabling multi-vendor interoperability across whatever application area the world’s growing cast of Ethernet users seeks to enable. Ethernet has always been and will always be about connectivity and how far this technology can go, but the Ethernet community embraces that the need for speed is relative to the given application. In years, since 1995 until 2010, the Ethernet’s evolution was somewhat slow in pace and in- novation was mostly simple. Ethernet speed increased linearly - approximately an order to an extent every few years like 10 Mbit/s to Fast-Ethernet 100 Mbit/s and from 1G to 10G. Conse- quently, around 2010, the first 100G Ethernet version 100GBASE-SR10 was introduced. Below are some of the trends for this development. 25GBASE-SR: Over the development of 100GBASE-SR4 in 2015, it became deem compulsory to develop the intermediate speed 25GBASE-SR to comply on standards as IEEE 802.3 by 2016. This transceiver utilizes the popular SFP+ form factor with LC-Duplex connector interface but with 25G speed. Meanwhile known as SFP28 and known to have collective four 25G server ports at one 100G switch port. 2 www.cbo-it.de
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  50GBASE-SR: Designed tocombine four 50G server ports to a 200G switch port. Available in the market since 2018. The transceiver has the SFP+ form factor with LC- Duplex connector inter- face, but in this case it runs with 50G speed and is called SFP56. 100GBASE-SR2: The objective of this standardization project is to aggregate two 50G server ports at one 100G switch port. This Ethernet version will be available along with the 50GBASE- SR. The transceiver will have the QSFP form factor with LC Duplex connector interface. 200GBASE-SR4: It will become available to the market together with 50GBASE-SR4 and 100GBASE-SR2. The configuration is expected to conform with the earlier series of Ethernet SR4 devices. Based on the released road map of the Ethernet Alliance in 2015, which outlines the response of Ethernet to the ever-increasing desire for higher bandwidth in data centers, Ethernet speed is shown to have unprecedented level of activity in the low end of the market, this roadmap also shows Ethernet speed in the future. After the ratification of IEEE 802.3by 25GbE in June 2016, we can now see that a new Ether- net speed becoming the new common standard. 25GbE which is designed to replace 10 GbE because of its cost effective and power efficiency to various application like ToR switching for cloud providers. This new trend will also help the demand for the huge data volume as well as the speed needed for the internet of Things. Furthermore, this development focuses primarily to the fiber-based SFP28 and QFSP28 market for the purpose of backbone or longer-haul con- nections. 3 www.cbo-it.de
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  3. TheAdvantages ofaQSFP28TransceiverSolution The QSFP28 transceiver is projected as the prospective interface by the Ethernet Alliance. This transceiver enables network bandwidth to be cost effective and resource saving. It is designed for 100GbE speeds using the 4x25GbE wiring specification, hence the “Q” which stands for quad. The QSFP28 form factor retains the usual density of 48 ports in a 1U tall switch which is very advantageous to existing systems without the need to migrate the network to a new stan- dard. Moreover, QSFP28 increases the density but minimizes the power consumption. QSFP is slowly becoming the universal form factor for various reasons. First, it increases front panel density by maintaining the form factor and the maximum number of ports but increases the lane speed from 10Gbps to 25Gbps. Secondly, it supports both cables and transceivers. Using QSFP28, a one-rack unit switch can accommodate up to 36 QSFP ports. Lastly, QFSP28 can use either VCSELs for short distances or Silicon photonics for longer distanc- es to support data center to reach for more than 2 kilometers of interconnection. With all these benefits coming to a single form factor, the next versions of high- bandwidth switches, routers and adapters will feature QSFP28 ports to ensure 100GbE data center inter- connection. 4 www.cbo-it.de 4. 25GbESFP28, today’s new TransceiverStandard 25GbE is already an emerging standard for Ethernet connectivity that will be beneficial to cloud and enterprise data center environments. Due to the Consortium that was established in June 2014 an Ethernet Task Force was created to encourage 25GbE technology and successively, to further develop the standard - the IEEE P802.3by. Moreover, the IEEE P802.3bq 40GBASE-T Task Force adopted objectives to likewise improve BASE-T support for 25GbE. There are various market drivers why 25GbE standard emerged. The main reason is, it provides a server connection speed faster than 10GbE that is optimized for cost, throughput and efficien- cy. Moreover, it maximizes efficiency of server connections to access switches in data centers. Lastly, this leverages four 25Gbps lanes (IEEE 802.3bj) running on four-fiber or copper pairs in- dividually transmitting at 25Gbps. This sums up to a backplane of 100GbE per form factor. Every lane needs a Serializer / Deserializer (SerDes) chipset. This twisted-pair concept originates from the 40GbE standard development. The below table shows a synopsis of fundamental upcoming IEEE standard interfaces that specify 25GbE.
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  Four parallel SerDeslinks between the Ethernet chip and the QSFP pluggable module is the composition structure of the so-called 40GbE interface. It remains indispensable to have four parallel 10Gb streams in extending QSFP onto fiber to transport this to the receiving QSFP (i.e. parallel optics). Short reach QSFP interfaces utilize four pairs for the transmission. Long-reach QSFP interfaces use an internal Coarse Wave Division Multiplexing (CWDM) to transport the four 10Gb streams over a single pair of fiber. The requisite of four lanes substantially decreases switch port density per switching chip and escalates the cost of cabling and optics. The 25GbE standard leverages the availability of a 25Ghz SerDes and requires only a single SerDes lane, while delivering 2.5 times more throughput compared to 40GbE solutions and significant CAPEX savings compared to 40GbE solutions. Moreover, existing several blade server chassis solutions have limits of only two SerDes lanes for their LAN on Motherboard (LOM) networking ports, hence, they can’t implement a four- lane 40Gbps interface. IEEEerror correction code for 25 GigabitEthernet Starting with 10GbE and 10Gb Fibre Channel Inter-Switch Links (ISLs), the “64b/66b” encoding scheme is used to develop data transfer efficiency. The 64b/66b encoding outcomes a 3% overhead (66-64) /66 on the raw bit rate. To pay off, Clause 74 (Fire code) FEC was presented to deliver extra error protection. 25GbE specification both supported Clause 74 FEC and Clause 91. Auto-negotiation can deter- mine whether Clause 74 FEC, Clause 91 FEC, or no FEC is employed on the link. Auto-Negotiation for 25 GigabitEthernet Specifics of auto-negotiation capabilities aren’t fully established or implemented. The 25GbE and 50GbE solutions are nevertheless backward and forward compatible with 10GbE, 40GbE, 100GbE and 400GbE products since they use the same IEEE 802.3 frame format. However, switch port capability to automatically select a different speed is still under development. 5 www.cbo-it.de
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  Different Form Factorsfor 100G and25G Shown here below, the 25GbE physical interface description supports various form factors: 6 www.cbo-it.de Currently some available Switches don’t support direct 25GbE connections by means of a SFP28 Direct Attach Copper (DAC) cable. The usage of a breakout cable that permits 4x 25GbE ports to connect to a 100GbE QFSFP28 switch port is one of the suggested solutions. Lengths of Direct Attach Copper (DAC) cable are limited to five meters for 25GbE. To support longer lengths, Ac- tive Optic Cable (AOC) solutions can be utilized as well. PCIExpress (PCIe) Interfaces The PCIe 3.0 interface is present-everywhere transversely in shipping server platforms. Due to cost, the preference in cloud and web-scale server deployments is headed for single-port Eth- ernet connectivity. These volume servers usually have PCIe 3.0 x4 slot(s). The table below shows why 25GbE is an easier move to upgrade from 10GbE lanes for it entails half the number of PCIe lanes and fits into the existing model against 40GbE lanes, resulting to better PCIe bandwidth usage and lower power impact. PCIe 3.0 Lanes required for Ethernet Generations Form Factor Lanesand Speed QSFP28 4 x25Gbps SFP28 1 x25 Gbps Ethernet SinglePort Dual Port 10GbE 2 4 25GbE 4 8 40GbE 8 16 100GbE 16 32
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  Conclusion: 25GbEreplaces 40GbE 7 www.cbo-it.de Theconsortium held in July 2014 was a call for interest of members who unan- imously agreed to support the development of a new standard for servers and switching. They created the 25Gbps Ethernet Task and developed the 25Gbps standard. There is a fast progress of this standard due to the high leverage of the existing standard for 100GbE as the base standard. The new 25GbE standards maximizes server efficiency to access switch interconnects and provides an op- portunity for optimum cost/performance benefits. It will provide up to 2.5 times faster performance than existing 10GbE connections while maximizing the Eth- ernet controller bandwidths/pin and switch fabric capability. More than 50% of the rack interconnect cost per unit of bandwidth can be saved and significantly improve an operator’s bottom line. Furthermore, it increases network scale and accommodate higher server density within a rack than what is currently achiev- able with 40GbE ToR links. In short order, deploying 25GbE solutions, something that solutions built on the more complex 40GbE standard can never achieve.
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  © 2019 CBO-All rightsreserved. BlueOptics andBlueLANincluding their Logosaretrademarks from CBOregistered in Germanyand/or other countries. Other namesandbrandsmentioned in this document maybe claimed asthe property ofothers. This document is for informational purposes only and does not set forth any warranty, expressed or implied, concerning any equipment, equipment fea- tures, or service offered or to be offered by CBO.Thepublication of information in this data sheet does not imply freedom from patent or other protective rights of CBOor others. In accordancewith the CBOpolicy of continuous improvement specifications maychange without notice. Contact aCBOsalesoffice for information on feature and productavailability. CBOGmbH Friedhofstraße 25 45478 Mülheim an derRuhr https://www.cbo-it.de/ info@cbo-it.de 0208 777 247-0 fb.cbo-it.de tw.cbo-it.de li.cbo-it.de yt.cbo-it.de KEEPIN TOUCH