Better experience to the cloud with Optical LAN

by | Jan 29, 2019 | White Paper

Optical LAN enables superior traffic management for modern enterprise LAN architecture for better network performance to the cloud.

The days of building local area networks (LAN) to support telephones, desktop workstations and locally switched traffic have passed. Ten years ago, LANs were designed to support peer-to-peer traffic flows because 80% of the traffic stayed local, but today it is expected that 90% of LAN traffic flows directly to the Wide Area Network (WAN) .

LAN traffic has made a 180-degree change in direction because of browser-based applications, wireless (e.g. 5G, Wi-Fi), employee personal traffic, hosted/managed and cloud-based services. The modern high-performance corporate LANs need to support new smart building systems, a wide range of mobile devices (e.g. BYOD), cloud computing and a constant influx of new software applications. IT professionals also find themselves balancing corporate data, employee personal data, external malicious attacks and internal security vulnerabilities.


Figure 1.

With changes in the workplace come changes in LAN traffic management, which trigger a corresponding change in the LAN infrastructure architecture. Copper-based LANs were once adequate for telephones and desktop workstations, but their architecture is cumbersome, less secure, inefficient and expensive with the advent of smart buildings, wireless and the cloud-computing evolution.

The purpose of this traffic management overview is to provide IT professionals with success-based guidance related to:

  • Common LAN traffic restrictions
  • Converged services and networks through traffic segmentation with hard Quality of Service
  • Cost-effectively managing LAN traffic bandwidth requirements and new traffic flow
  • Applying Optical LAN as a simple and secure solution for modern corporate LANs

Common LAN traffic restrictions
One indisputable fact is that fiber provides greater bandwidth than copper cabling. For example, single-mode fiber has proven capacity measured in terabytes . It is prudent for IT professionals to investigate common traffic restrictions for both Optical LAN and legacy copper-based LANs that exist at the connection to Wide Area Network (WAN) or Internet Service Provider (ISP), core router, shared resources, split ratios and oversubscription/concentration.


Figure 2.

WAN/ISP Connectivity — Today the majority of LAN traffic is destined for the WAN. The question becomes, what size WAN/ISP connection has a company purchased? More than likely the WAN/ISP connection capacity is measured in Mbps and shared across all users and IP/Ethernet end-points within an enterprise facility. Even if a large corporation has purchased outside connectivity measured in Gbps, it is highly unlikely that internal math would prove that all users and IP/Ethernet end-points are receiving gigabit-rate data speeds. For a 1,000 user/end-point enterprise corporation example, a 48-port gigabit Ethernet workgroup switch would need to be only equipped with 40 user/end-point connections and be uplinked with four 10 Gbps interfaces. The core router would then need the density to aggregate one hundred 10 Gbps interfaces traveling back from twenty-five 48-port Gigabit Ethernet workgroup switches. Ultimately the core router would need to have a terabyte connection to the WAN/ISP, or ten 100 Gbps, or twenty-five 40 Gbps or one hundred 10 Gbps interfaces — all of those scenarios would be VERY expensive, at best 99.9% availability (~5.5 hours of down time annually) with ZERO redundancy resiliency and thus highly unlikely to exist in the real world .


Figure 3.

Core Router — The core router in the building’s main data center is the focal point of all the LAN’s traffic. It provides connectivity to WAN, ISP, external VPNs, all content and all corporate resources. This location in the network requires the highest degree of attention to ensure that no traffic bottlenecks exist and no security breaches occur. The core router is a sophisticated piece of equipment and an expensive one. Since Optical LAN has superior aggregation and distribution, by deploying Optical LAN you can save ports on the core router, thus saving money on the core router and saving money on your total LAN infrastructure.

Shared Resources — Ethernet by nature is a shared resource . Passive Optical Distribution Networks are negatively described as a shared resource across their 1:x Passive Optical Network splitters. However, it is also a fact that everything on a legacy copper-based active Ethernet network is shared beyond the first 100-m/300-ft point-to-point CATx cabling drop. Furthermore, ever-popular cloud-based networking technologies are shared resource as well, and there are good business reasons why shared resources are acceptable. As with cloud-based computing, Optical LAN takes advantage of this architecture to simplify the LAN, lower costs, reduce energy consumption and save space without sacrificing any security.


Figure 4.

Split Ratios — With Optical LAN, passive optical distribution splitters are used throughout the distribution, aggregation and access networks. These splitters commonly are deployed in 1:2, 1:4, 1:8, 1:16 and 1:32 increments. Similarly a legacy copper- based Active Ethernet workgroup switch provides a 1:24 or 1:48 split ratio . That is, these workgroup switches share a common uplink across either 24 or 48 ports. At an even more granular level, one would find that 24- or 48-port workgroup switches or 24- or 48-port service module subcomponents are composed of 1:4, 1:6 and 1:8 Ethernet chips that have 1 Gbps or 4 Gbps trace back to a supervisor engine. All of these embedded splits of legacy copper-based Active Ethernet are NOT exposed to network architects and engineers. Therefore, the benefit of Optical LAN optical distribution splitters is that they provide network architects and engineers with the flexibility to match low- bandwidth, high-density end-points with high split ratios and high-bandwidth, low density end-points with smaller split ratios.


Figure 5.

Oversubscription/concentration — Whether we are examining WAN/ISP connectivity, core router, shared resources and/or split ratios, oversubscription (or concentration) exists at many points in the network. And in fact, copper-based LAN design guidelines call for 20:1 oversubscription/concentration because typical campus networks are engineered with oversubscription. It is not generally practical to provide line rate for every port upstream from the access-to-distribution switch, the distribution- to-core switch or even for core-to-core links.” The highest levels of oversubscription/concentration will occur near the WAN/ISP connectivity and core router .


Figure 6.

What is important to IT professionals is providing traffic management for the best possible network performance by taking advantage of Optical LAN’s superior security, segmentation and QoS capabilities.

Converge services and networks through segmentation with hard QoS
To ensure the highest degree of LAN performance, traffic management needs to balance bursty traffic, interactive traffic, real-time latency-sensitive traffic and nonreal-time traffic. Optical LAN can accomplish the highest end-to-end LAN performance through traffic segmentation, low latency and QoS mechanisms while drastically improving network security compared to the legacy copper-based LAN alternative.

Segmentation — Legacy copper-based LANs that place all traffic in a single broadcast domain can easily overload the network. The better design is to create traffic (service) segmentation through advance VLAN capabilities. Optical LAN enables service-level VLANs that segregate and secure data flows to Optical Network Terminal (ONT) Ethernet ports. VLAN trunking, termination and translation allow for rate shaping on a per service type. Traffic classification is accomplished per IEEE 802.1p, IEEE 802.1q and even DSCP to guarantee voice quality. With VLAN trunking, you can support multiple services and multiple end-devices per ONT Ethernet port.

Latency — Network performance is affected by a large number of factors in addition to bandwidth. Increasing bandwidth capacity does not directly equate to better network performance. Service performance is also directly dictated by latency (the effect of physical distance on physical communications media), jitter, packet loss and congestion. Optical LAN has proven 1 ms latency measured during formal multivendor end-to-end interoperability testing at U.S. Department of Defense certification through Joint Interoperability Test Command (JITC). In 2008, the U.S. Department of Energy (DoE) brought together more than 60 experts from the energy, telecommunications and IT industries. The DoE wanted them to brainstorm ways to improve efficiency of, among other things, data centers and telecommunications equipment. One of their findings states that reducing the number of optical- to-electrical and electrical-to-optical conversions results in better network performance and lower energy consumption — Optical LAN does exactly that. In fact, Optical LAN can eliminate all of the O-E-O conversions over a 30 km/18 mi reach.

Quality of Service — Strict QoS is delivered through Optical LAN via better end-to-end traffic segmentation/classification, rate limiting, policing, queue management, scheduling and shaping mechanisms.

As stated, the above traffic classification is done for all ingress traffic (e.g., Data, VoIP, POTS, IP Video) based on traffic type defined by VLAN during provisioning (per Dest MAC, VLAN, 802.1p marking, DSCP marking). Rate limiting and policing is defined in the Service Level Agreement by setting Committed Information Rate (CIR), Excess Information Rate (EIR) and Access Control List (ACL) filters. This sets the guaranteed bandwidth per user, per service or per end-device while smoothing bursty traffic and establishing ultimate rate limits. Based on traffic management criteria, the system then employs Tail Drop or Weighted Random Early Discard (WRED) modes against throttled traffic. At that point, queue management kicks in. Optical LAN supports eight (8) class queues available within the network and four (4) class queues available at each end port. This ensures strict traffic delivery based on hard QoS parameters by providing IT professionals with granular traffic shaping capabilities .


Figure 7.

Furthermore, Dynamic Bandwidth Allocation (DBA) is a mechanism in Passive Optical Networks (PON) that orchestrates upstream bandwidth management to a single Optical Network Terminal (ONT) based on the total network bandwidth utilization observed across all connected ONTs. This is possible because the Optical Line Terminal (OLT), and all connected ONTs, work in concert together due to PON technology’s centralized intelligence and management. DBA enables the OLT to make real-time “dynamic” upstream traffic management decisions based on observing idle ONTs, and busy ONTs, and thus granting underutilized upstream bandwidth to the ONTs that are experiencing the highest traffic demands. DBA helps smooths the bursty nature of network traffic, improves the end-to-end LAN performance and ensuring the best user experience across the entire network.

It should also be noted that Tellabs Optical LAN enables network managers to create global profiles related to particular services, segmentation, QoS and security that can then be aligned with specific users and IP/Ethernet end-points. If an individual user moves to a new location, those profiles automatically follow that user. This helps speed the process of Moves, Adds and Changes within a LAN and simplifies day-to-day network management – with more automation through plug-and-play and machine-to-machine functionality.

Cost-effectively manage LAN traffic bandwidth requirements and new traffic flow
Back in the days when IT professionals did not have the ability to enforce traffic management policies, LANs required relatively big pipes operating at 50% capacity to ensure no collisions. When IT professionals take advantage of traffic management policies of strict service segmentation and hard QoS, you may be surprised at the true real-world bandwidth requirements of the most common LAN services.

In 2013, Gartner Research did a study of estimated peak band- width per user in a commercial Enterprise LAN and found that 200 Kbps was more than sufficient. This study took into consideration the impact of video, wireless and cloud computing on the LAN. Then Gartner Research went on to estimate the future expansion of video, wireless and cloud computing, and offered forecast of projected peak bandwidth per user. The outcome of the research stated that heavy video, wireless and cloud computing would require bandwidth per user in the 1 Mbps to 7 Mbps range.

Furthermore, In a 2015 technical case study sponsored by Microsoft (updated in 2018), a study was done on a large corporation deploying Microsoft Office 365. The purpose of the technical case study was to optimize network capacity and performance relative to cloud-based services in an highly complex global work environment. The outcome of their research was that a the typical corporate user requires 400 Kbps of bandwidth during normal business activity.

Optical LAN can deliver symmetrical gigabit rate service at an ONT 10/100/1000 RJ-45 Ethernet port. When and where to allocate gigabit rate service is at the discretion of the network architects and engineers. Based on Gartner and Microsoft studies, one can see that guaranteeing 10 Mbps or 100 Mbps service rates is more than sufficient for most LAN services, including video, wireless and cloud computing. In fact, while network managers can create global traffic profiles at 10 Mbps or 100 Mbps rates and align them with users, ports and services, the Optical LAN transport can always accelerate to gigabit rate speeds as network congestion allows.

The above facts beg the question, why invest in a copper-based LAN whose dedicated one gigabit point-to-point access cannot support one gigabit bandwidth throughout the LAN? Furthermore, the copper-based LAN architectures of a hierarchy of stacked switches and meshed CATx cabling do not reflect the needs of modern LAN traffic flows derived from video, wireless and cloud-computing growth. Perhaps the best advice for CIOs and IT professionals is to simplify the LAN infrastructure and focus more resources toward WAN, ISP, core switching, building automation, wireless and cloud-computing technologies that are demanding the most attention these days .


Figure 8.


In short, Optical LAN outperforms copper-based LANs with better end-to-end network performance to the cloud. Optical LAN is proven:

  • Simple
  • Secure
  • Stable
  • Scalable
  • And, it costs less

Optical LAN is the simple and secure solution for the modern corporate LAN
With the complexity of the traffic traveling across the LAN, there comes the need to simplify the underlying LAN infrastructure. At the same time, network security needs to increase due to internal and external threats.

Simplify — Optical LAN is simple because it significantly reduces the number of managed devices within a LAN. Fewer moving parts mean less things to buy, rack, stack, power, A/C, ventilate, provision and manage, and fewer things to break. IT staff can take comfort knowing that Optical LAN does not change the end-points. It continues to leverage existing core switches, PBX, VoIP, unified communications, POTS, data, wireless access, surveillance, security and building automation. By simplifying the LAN, the IT staff workload is greatly reduced. Furthermore, Optical LAN converges whole networks and their services into one fiber infrastructure. In the past, disparate networks were built and maintained for separate voice, video and a multitude of data traffic across wasteful redundant cable plant — this convergence can help IT staff with legacy network modernization regardless of IP voice or analog voice, IP video or RF video, wireless access and all smart building services.

Security — Traffic is more secure on Optical LANs than copper-based LANs. Fiber is not subjected to electromagnetic interference, radio-frequency interference (RFI), or electromagnetic pulse (EMP). Copper acts like an antenna and broadcasts radio frequencies that can be intercepted without a physical tap. Fiber is more difficult to physically tap, and stateful Optical LAN protocols preclude malicious taps without detection. Optical LAN uses robust security at Optical Line Terminals (OLT) and ONTs with protection at the physical, data and user layers. Network Access Control authentication and authorization is managed through IEEE 802.1x, RADIUS and strict user-definable roles for the element management. Malicious attack barriers are established with Access Control Lists and other Denial of Service protection functions.

With Optical LAN simplified network design also comes significant reduced points of network vulnerability, and less human touch, which both directly improve security.

Private entities in healthcare, education, finance, banking, utility, transportation and gaming can have total confidence with Optical LAN’s superior security, considering how the U.S. military and security agencies rely on it. Optical LAN is a trusted infrastructure for high-security networks in the U.S. Department of Defense, Energy, Homeland Security, and National Security Agency. Tellabs Optical LAN is certified JITC-approved for high availability networks, and Certified TEMPEST Technical Authority (CTTA). For Top Secret networks, Tellabs Optical LAN has also been tested, certified and deployed in highly classified U.S. government facilities using alarmed armored fiber in hardened carrier Protective Distribution System (PDS) architecture. This Tellabs Protect solutions can save up to 66% in installation and 75% in operational costs for infrastructure and asset protection compared to traditional PDS design.


LAN built for today’s high-performance buildings, mobile, cloud and collaboration

For decades, copper-based LANs have been designed and deployed in the same architecture based on serving telephones and desktop computers. We witnessed CATx cabling struggle to keep pace moving from CAT3 to CAT6, and now CAT8 is being defined by the standards bodies. We have seen fork-lift equipment upgrades from Fast Ethernet to Gigabit Ethernet and now again with 10 Gigabit Ethernet. Technology has progressed, and now IT professionals are challenged by smart buildings, mobile wireless (including BYOD), cloud-based services, business analytics, business intelligence, big data and a constant influx of new applications. Yet the meshed, stacked hierarchy of copper-based Active Ethernet LANs has maintained the same telephone and desktop computer footprint?

Optical LAN can provide a simple and more secure LAN than is possible with copper-based LANs. IT professionals have the means to accurately manage common LAN traffic restrictions and to converge services and networks through traffic segmentation with hard QoS to ensure the highest LAN performance. In the end, Optical LAN is the best solution possible to cost-effectively manage traffic bandwidth requirements resulting from new traffic flow patterns in the modern LAN and ensuring the better end-to-end network performance to the cloud.


John Hoover, Tellabs Marketing Director
John Hoover
Director of Marketing
John Hoover is a Marketing Director at Tellabs and 2024 Board Chair of the Association for Promoting Optical LAN (APOLAN). Over the past 20 years, John has influenced industry milestones such as early passive optical network deployments, video implementations, wireless and more recently enterprise Passive Optical LAN adoption.