Addressing Scaling Challenges in the Data Center DELL PowerConnect J-Series Virtual Chassis Solution A Dell Technical White Paper Dell Juniper
THIS WHITE PAPER IS FOR INFORMATIONAL PURPOSES ONLY, AND MAY CONTAIN TYPOGRAPHICAL ERRORS AND TECHNICAL INACCURACIES. THE CONTENT IS PROVIDED AS IS, WITHOUT EXPRESS OR IMPLIED WARRANTIES OF ANY KIND. 2010 Dell Inc. All rights reserved. Reproduction or translation of any part of this work beyond that permitted by U.S. copyright laws without the written permission of Dell Inc. is unlawful and strictly forbidden. For more information, contact Dell. Dell, the DELL logo, and the DELL badge, and PowerConnect are trademarks of Dell Inc. Juniper Networks, the Juniper Networks logo, Junos, Steel-Belted Radius, NetScreen, and ScreenOS are registered trademarks of Juniper Networks, Inc. in the United States and other countries. Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products. Dell Inc. disclaims any proprietary interest in trademarks and trade names other than its own. September 2010 Page ii
Contents DELL PowerConnect J-Series Virtual Chassis Solution... i A Dell Technical White Paper... i Dell Juniper... i Executive Summary... 2 Data Center Network Challenges... 2 Design and Operations... 3 Performance... 4 Resource Consumption... 4 Dell PowerConnect J-Series Virtual Chassis Technology... 4 Reduced Complexity... 5 Improved Performance... 6 Cost-Efficient Use of Resources... 6 Conclusion... 6 References... 7 About Dell... 7 Tables Table 1. Deployment scenarios... 3 Figures Figure 1. Legacy data center architecture... 2 Figure 2. Dell PowerConnect J-EX4200 Virtual Chassis technology... 5 Page 1
Executive Summary Today s demands on data center computing and network resources pose operational, performance, and scaling challenges for traditional three-layer hierarchical network architectures. This paper describes how Dell PowerConnect J-EX4200 Ethernet Switches can apply Virtual Chassis technology to resolve these challenges by simplifying network design and operations, improving performance, and reducing rack space and power consumption. The Dell PowerConnect J-Series product family delivers open and flexible solutions for datacenters and enterprise networks, with technology powered by Juniper Networks, the Junos Network Operating System software, and management applications from Juniper Networks. Data Center Network Challenges Data centers using legacy architectures (built within the last five years) are faced with complexity and inflexibility in the access layer, poor performance, and excessive resource consumption, as illustrated in Figure 1. Figure 1. Legacy data center architecture Page 2
Design and Operations Data center networks often employ one or more designs to provide access layer connectivity for customers. Two popular methods are top-of-rack and end-of-row deployments, and there are advantages and disadvantages to both approaches. Table 1. Deployment scenarios for access layer switches Deployment Method Advantages Disadvantages Top of Rack Simplifies cable management since customer connections are intra-rack (copper or fiber) Easier to make changes End of Row Easier to manage because there is only one IP address, one image, and one configuration file Provides flexibility with uplinks in the core Numerous inter-switch connections reduce access ports for customers Increases control plane complexity Consumes more space, power, and cooling resources Costly cable management Despite their advantages, the decision to use one or the other affects the ability for operators to efficiently roll out new services or to make changes in the network. For example, live server migration requires access layer changes to be adapted quickly. Such changes require that devices appear as though they are seamlessly connected on the same LAN, regardless of their actual proximity to each other. This level of transparency between systems allows you to easily maintain server uptime and migrate computing loads within the data center or across multiple data centers. Although virtual private LAN service (VPLS) can be used to extend Layer 2 access inside and outside of data centers, it is not always practical, since it shifts the problem to high-end systems responsible for transporting data outside of the data center. This inflexibility in network access adversely affects the operational efficiency of the entire data center. In addition to how boxes are physically connected and oriented in the network, the actual operating of the network is a challenge when existing methods are not allowing engineers to do their jobs efficiently. Everyday tasks, such as the following, become difficulties as the number of independent devices in the network increases. Monitoring device health Troubleshooting Configuration management Software upgrades Such operational challenges are further compounded if devices are running different versions of software or have different configurations. In addition, software must be carefully managed across these independent devices to ensure consistent functionality and to limit exposure to bugs or other vulnerabilities. There may also be special training or expertise needed to support these configurations. The manpower needed to adequately operate, maintain, and troubleshoot the unique requirements of each network device can be enormously time-consuming and thus, cost inefficient. Page 3
Performance Today s data center architectures suffer from increased latency, added delays in network convergence, and limited availability of bandwidth. These problems are directly related to the complexity of the network. Latency caused by the network architecture Server-to-server traffic within the data center normally travels from the access layer up to the core and then back down again to the access layer, which is a costly, uneconomical use of network assets. Suboptimal use of access and uplink ports 50% of the access layer switch ports are used for inter-switch connections and the remaining ports are used for customer connections, consequently limiting available bandwidth. Layer 2 control plane scaling Spanning Tree Protocol (STP) can take up to 50 seconds to converge in a network, while the Rapid Spanning Tree Protocol (RSTP) can require tens of seconds to converge in some topologies. Additionally, virtualized servers compound these problems as they require high performance and low latency. Resource Consumption The inability to efficiently scale bandwidth in modern data centers compels operators to actually add more of the same inefficient devices to the network to meet growing bandwidth demands. These extra devices consume additional rack space, and additional power and cooling. This excess consumption of resources is detrimental to data infrastructure because once a data center runs out of power, a new data center will have to be built. Clearly this is an enormously costly and ineffective way to conduct business. In 2007, it was projected that data center power consumption would double between the years 2006 to 2011 from 7 to 12 GWh (gigawatt hours). To put the 2006 numbers in perspective, the required output is equivalent to 15 baseload power plants. By 2011, total consumption totaling 12 GWh would require an additional 10 baseload power plants. 1 (Baseload is the minimum power a company must make available to its customers, or the power required to meet minimum demands based on reasonable customer requirements.) Dell PowerConnect J-Series Virtual Chassis Technology Virtual Chassis technology on the PowerConnect J-EX4200 allows for the interconnection and operation of multiple switches as a single, high-bandwidth device (as shown in Figure 2). Up to 10 J-EX4200 switches can be interconnected with dedicated Virtual Chassis ports on each device or through optional GbE and 10GbE uplink ports that are configured as Virtual Chassis ports. The combined backplane bandwidth is up to 128 Gbps. Key benefits of Virtual Chassis technology are as follows: 1 Report to Congress on Server and Data Center Energy Efficiency. 2007. U.S. Environmental Protection Agency. Page 4
Simplified overall system maintenance and management through a single management interface. For example, a single logical switch reduces the number of managed devices by up to a factor of 10. Pay-as-you-grow scalability from 24 to 480 10/100/1000 Mbps ports. Extension of the Virtual Chassis configuration by up to 50 km with redundant fiber links in between. Consistent, modular Junos operating system control plane feature implementation. Improved network convergence. Decreased latency. Reduced rack space, and reduced power and cooling resource consumption. Figure 2. Dell PowerConnect J-EX4200 Virtual Chassis technology Reduced Complexity With Virtual Chassis technology in Dell PowerConnect J-Series switches, access layer components can leverage the benefits of both top-of-rack and end-of-row access switch deployments without having to choose between the two. Simplifies cable management since customer connections are intra-rack (copper or fiber). Makes configuration changes easier. Reduces maintenance efforts because there is only one IP address, one image, and one configuration file. Provides flexibility with uplinks in the core. Page 5
A Virtual Chassis simplifies the data center network by collapsing portions of it. This is accomplished by each Virtual Chassis member interconnecting via high-speed backplane connections (Virtual Chassis ports), conserving valuable access ports, and effectively turning what normally would be many LANs into one. Thus, the layers of switching required for network access are reduced. This flexibility allows you to extend a single Layer 2 access network beyond a single rack, reducing efforts required for network changes such as live server migrations. Moreover, a Virtual Chassis can extend Layer 2 access between sites by up to 50 km in distance. This simplistic and innovative approach to networking, along with high-performance packet forwarding capabilities, greatly minimizes efforts required to deploy new services. Improved Performance Not only do J-EX4200 switches have the very low port-to-port in-switch latency (2-3 µs), but their Virtual Chassis technology also further decreases latency by flattening the network. Traffic is routed over special backplane Virtual Chassis ports for inter-switch traffic, rather than switching and flooding traffic over access ports. Another benefit of this design is that node and link failures have sub-second failover times without the need for an external, Layer 2 control plane protocol, like STP, to create a loop-free topology. Bandwidth availability is improved over traditional switches through the use of backplane connections for inter-switch linkage and line-rate performance for all packet sizes. These backplane inter-switch connections reduce the number of necessary devices, saving data center resources for better use. Cost-Efficient Use of Resources Dell PowerConnect J-Series Virtual Chassis technology combines the scalability and compact form factor of standalone switches with the high-performance backplane bandwidth characteristics and high port densities of traditional switches. Such configurations enable economical deployments that deliver network availability in locations where installation might otherwise be cost prohibitive or physically impossible. Rack space, power, and cooling resources are protected since a Virtual Chassis facilitates the efficient use of both access and uplink ports. Also, by eliminating unnecessary switching layers, a Virtual Chassis architecture dramatically reduces the equipment and the resources required to plan, deploy, implement, and operate today s corporate network. Conclusion The Dell PowerConnect J-EX4200 with Virtual Chassis technology delivers a highly scalable solution that reduces network complexity, increases access flexibility, improves performance, and reduces resource consumption. This package, together with market-leading port densities and the proven Junos OS, increases operational efficiencies in a streamlined manner. The result is lower operational, maintenance, and troubleshooting costs, translating to a more costeffective solution for your business. Page 6
References Virtual Chassis Technology Best Practices. 2009. Juniper Networks implementation guide. About Dell Dell (NASDAQ: DELL) is a leading technology provider to commercial and public enterprises around the world. Page 7