Aug 14, 2012
The New Networking Landscape
Virtualization is transforming data center networks. These networks are under pressure to adapt to workloads that are no longer bound by physical constraints. Because a virtual machine can show up anywhere, the network must be able to respond with a predictable level of service. Today’s network architects and engineers have a multitude of options to meet these demands. We'll look at significant data center network technologies in three major categories: Layer 2 multipathing, Layer 2 extension and software-defined networking.
Layer 2 multipathing tackles the built-in limitations of Spanning Tree Protocol by enabling all links to forward traffic while ensuring redundancy and eliminating loops that could take down a network. Options include MLAG and virtual chassis, which allow multiple switches to act like a single device. Emerging protocols such as TRILL and SPB let designers create meshes or fabrics that enable traffic to take the shortest path between switches.
Layer 2 extension allows physically separate data centers to be linked into a Layer 2 domain across Layer 3 boundaries. Originally aimed at carrier networks, some Layer 2 extension protocols are appearing the data center because they support the ability to move VMs from one data center to another, an ideal capability for load sharing, business continuity and disaster recovery. We look at Cisco's Overlay Transport Virtualization, the Virtual Extensible Local Area Network, Network Virtualization using Generic Routing Encapsulation and Stateless Transport Tunneling.
Software-defined networking is emerging as an alternative to the traditional switch model in which the control plane resides within each switch. By contrast, SDN moves decision-making into a centralized controller. This can make the network more flexible and better able to respond to changing demands. In addition to SDN, we'll dig into OpenFlow, a new protocol for communicating between switches and a controller. We examine the potential implications of SDN and OpenFlow and evaluate its impact on data center networks. (S5070812)