Technical white paper Converged Networks and Fibre Channel over Ethernet Table of contents Abstract 2 Introduction 2 Converged networks Data Center Bridging Fibre Channel over Ethernet (FCoE) 2 3 3 Challenges for end-to-end network convergence Servers Direct-attach storage Storage Area Network iSCSI: SANs using TCP/IP networks Cluster interconnects 4 4 5 5 5 5 Approaches to converged data center networks Convergence strategies Cost structure Congestion and flow control FCoE and DCB progress and cha
Abstract In this paper we examine requirements for converged networking up to the server edge and beyond for end-to-end network environments. We want you to understand how the HP vision for converging technology, management tools, and partner product portfolios aligns with those requirements. We also compare HP and Cisco approaches to converged networking so you can see the likely outcomes of the two strategies.
The benefits of convergence are clear: Converged networking reduces the number of required I/O ports. This means that smaller servers (including blades) with fewer available option card slots are ideally suited for taking advantage of converged networks and the reduced requirement for I/O ports for full connectivity. Furthermore, the savings from not purchasing and operating several fabric types and their server connections is substantial.
In a single-hop FCoE/DCB network architecture, a function within a switch known as a Fibre Channel Forwarder (FCF) passes encapsulated Fibre Channel frames between a servers’ CNA and the Fibre Channel storage area networks (SAN) where the Fibre Channel storage targets are connected. An FCF is typically an Ethernet switch with DCB, legacy Ethernet, and legacy Fibre Channel ports.
more connections for increased performance. Smaller servers, especially blade servers, have few option slots, and the Fibre Channel host bus adapters (HBAs) add noticeably to server cost. Therefore FCoE is a compelling choice for the first network hop in such servers. HP ProLiant BL G7 and Gen8 blade servers have embedded CNAs, called FlexFabric adapters, which eliminate some hardware costs associated with separate network fabrics.
Table 1.
Category Cisco HP FCoE Consolidate Fibre Channel traffic with Ethernet / push FCoE for data center Converge Fibre Channel at c7000 chassis level and in Networking devices where costs are justified and easily defended Lead the market in data center (multi-hop) FCoE via proprietary methods In advance of FCoE standards becoming economically viable and available in end-to-end network environments, HP recommends 3PAR Storage Solutions with Flat SAN technology as the preferred mechanism to provide end to e
Networks become congested like traffic after an accident. When an auto accident occurs at an intersection in the center of a big city, traffic backs up on the intersection, which in turn backs up traffic in adjacent streets until nothing can move within a full square mile. This is called “congestion spreading.” The methods for congestion management change with the standards employed. Table 4 shows those changes in different network enviornments and employing different congestion management technologies.
• Since FCoE was first announced, the Ethernet community has assumed that FCoE packets could move across any Ethernet switch that implemented the DCB features. Cisco’s direction represents a fundamental shift away from the Ethernet model and toward the Fibre Channel model in which storage networks always use switches from a single vendor. • Every switch in the data center requires Fibre Channel switch firmware. The connections between those switches are Virtual Ethernet (VE) Ports.
Figure 3: HP Virtual Connect FlexFabric direct-attach with FC based HP 3PAR Flat SAN technology Systems Evolution of storage It seems inevitable that the storage networking now accomplished with Fibre Channel will transition onto an Ethernetbased converged standard such as FCoE throughout most of the data center. In the past, several attempts at accelerating this transition assumed that a single and fairly rapid technology replacement would occur.
Conclusion Server virtualization is creating significant change, driving data centers to pool larger numbers of servers. There is a need to replace the rigid compartmentalized networks with a more flexible model which still contains the impact of a single runaway process or switch can have on the network. The winning approaches have not yet emerged, or more precisely, every vendor is selling you a different “winning approach” that addresses some but not all of these issues.
For more information Visit the URLs listed below if you need additional information. Resource description Web address Comparison of HP BladeSystem servers with Virtual Connect to Cisco UCS technology brief http://h20000.www2.hp.com/bc/docs/support/SupportManual/c03094466/c030 94466.pdf Converged networks with Fibre Channel over Ethernet and Data Center Bridging technology brief http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01681871/c016 81871.
