Network revolution: Software-defined network and network virtualization

Posted in2014-08-28 14:49| 5,691 Reads | Source OpenStack China Community | Reviews | author Zheng Summary:While SDN or network virtualization has not yet reached the desiredHigh, but for it practitioners, embracing these technologies is never too early, and Ethernet is now playing a pivotal role in every data center, but SDN vendors are gearing up for the next cyber revolution.

"Editor's note" Network after years of development, has come to the "post-Cisco" era, software-defined networks, network virtualization and other nouns have come to our eyes, this article focuses on the traditional network architecture and SDN network similarities and differences, the development of network virtualization, you can see, SDN manufacturers are gearing up, due to " We often overestimate the changes that have occurred over the next two years, and underestimate the changes that will take place over the next decade. "Traditional enterprises need to face the change of network operation form in the future, and the author discusses the future direction of network industry from the aspects of Network transformation and technology transformation.

The following is the original text:

the network industry is poised to change

At present, Ethernet has played a pivotal role in every data center, and it connects each company to the Internet. Every major change in the Web world requires a lot of time, although the public's acceptance of standards and new technologies is improving, and the popularization of new technologies will take more than 10 years. Enterprises need to cope with the growing demand for reduced budgets, and enterprise employees need an automated IT infrastructure to streamline their operations, and the Voice of the network world is focused on migrating from traditional Ethernet to software-based networking and network virtualization. Now that the internet world has been dominated by Cisco for years, the question is: How powerful are these new technologies to traditional networks? Does the customer have enough willingness to replace the vendors to adopt these new technologies?

Ethernet Fabrics (Ethernet), an alternative to the Spanning Tree Protocol architecture Network, has a scalable, high-bandwidth architecture, and SDN is more of an architecture than a product. Juniper and Arista have provided some programmable features in their product lines over the years. Let's start by looking at how SDN differs from traditional network architectures (the next two sections explain the difference by Joe Onisick's diagram and description)

Traditional Network Architecture

In the traditional network architecture diagram, the most important point is the separation of the control layer from the data layer . Each layer has a different task, the layer and the layer together provide the entire data forwarding, routing function. Here, the control layer is responsible for the configuration of the device and the programmatic routing of the data stream. When you manage a switch, you are actually dealing with the control layer of the switch. Like routing tables, spanning tree protocol These things are computed by the control layer. These tables are built from the delivery of message frames such as BPDUs (Bridge Protocol data units, which exchange information between switches running STP), hello packets, and the switch to determine the available forwarding paths based on these message frames. Once the forwarding path for these packets is determined, these path information is sent to the data layer, usually on top of the hardware. The data plane usually uses the latest path information transmitted from the control plane for message forwarding. This model is traditionally very efficient, the hardware decision-making process is very fast, the overall delay is controllable and the control plane can handle the heavy configuration requirements.

There is no problem with this approach, and our focus is on extensibility. To prove the scalability problem, we take quality of service (QoS) as an example. QoS allows specific data frames to be forwarded on a priority basis according to the characteristics of the frame, based on scheduling requirements. This mitigates some of the data transmission delays caused by a particular traffic in the network congestion. For example, latency-sensitive voice and video traffic is often prioritized for high-priority forwarding to ensure a user experience. Traffic prioritization is usually determined based on the service level (CoS) in the data frame or the Differentiated Service Code point (DSCP) label. These frames must be uniformly determined when the data frame enters the network, and the corresponding rules must be consistent across the network, which can become awkward in a traditional multilayer switched network because each device needs to have the same configuration information.

To illustrate the current network management challenges , let's consider that the administrator needs to be individually configured on each port on each device node in the network, which is time-consuming, error-prone, and clumsy.

In addition, there are challenges in the network where data is properly categorized and routed . For example, now we have two completely different kinds of data traffic, one is iSCSI traffic and one is voice traffic. iSCSI as a storage traffic, usually packets are full-size, and sometimes giant data frames, and voice traffic is usually a small packet of packets transmitted. In addition, there are different transport requirements for both types of traffic: voice traffic is sensitive to latency, which is to ensure the quality of the voice communication, while iSCSI is less sensitive to latency, but requires more bandwidth. There are few tools in traditional networks that can differentiate between these two types of traffic and choose different data paths depending on the type of traffic to meet the specific needs of both types of traffic. These are the issues that Sdn wants to solve.

the three main elements in SDN

• ability to manage data frames, packet forwarding, and application policies
• ability to dynamically apply policies and manage networks
• Programmable Capabilities

Note: In order to implement SDN, the network architecture does not need to be open, standardized, and interoperable with other networks. A suitable SDN can only meet the definition and requirements.

An SDN architecture must be capable of large-scale programming of manipulating data frames or packet traffic. Typically, hardware in SDN is often designed to converge (devices have the ability to host all data types, including some desired storage traffic), large, low-latency data transfer pipelines, which are often called fabric. The SDN architecture itself provides centralized management of network and network streams from a network layer perspective.

This architecture is implemented by separating control from the data-tier device and providing a programmable interface for the control layer. The data-tier device accepts the forwarding rules by the control layer and applies the rules on top of the ASIC hardware. These Asics can be traditional Asics, or they can be custom-defined forwarding chips based on functional and performance requirements. The relationships between these elements are explained:

In the diagram, the SDN Controller provides control layer functionality, while the data layer is provided with a physical switching device. These devices can be new or existing devices that load specific firmware, depending on the specific vendor and physical architecture model. One of the main advantages of the architecture in the diagram is that the visibility of the global is greater for the control plane. In addition to the fact that each data-tier device relies on other neighbor devices to obtain a network topology, a separate control layer will have a full network connection status. This architecture provides a network-wide routing, security, and QoS configuration, but also requires programmable features. Another major feature is centralized control, which makes it easier for centralized controllers to obtain real-time application data streams and to centralize data-making decisions.

The figure shows only a small part of the SDN architecture and focuses on the physical architecture and server location. In addition, this architecture integrates the virtual machine environment into the SDN network. This enables unified control policy management for both physical and virtual devices, which can be implemented through virtual Ethernet bridges that can be managed by SDN controllers in the virtual Machine Manager. The logical architecture of this solution is described in detail.

The solution to integrate virtual network system and physical network system is clearly described in the diagram. This architecture is extremely important because both the physical data layer and the virtual data layer are managed uniformly by the control layer, and when a virtual machine is migrated, he can ignore the underlying network architecture. This feature is important for the policy virtualization environment, because if finer grained control is implemented, the control policy can be placed on the virtual machine port and will take effect until the virtual machine goes out of the net.

Note: The above two diagrams are concept maps of the SDN architecture. In addition to the individual control of the node solution, there are many other architectures, described in this article is the most common application situation.

In architecture, centralized control and programmable interfaces in the control layer can be replaced by more sophisticated intelligent control processes to meet complex requirements such as traffic optimization, security, and maintenance. Traffic can be forwarded independently of each other based on network changes.

The Rise of SDN vendors

As many people have said, with the fall of Microsoft, the "post-PC" era is coming. With the advent of the post-Cisco ERA, the SDN potential will be propped up for a day.

Cisco– recently made a major strategic decision on its own open network environment (one)-see "Mike Fratto talking about computer networks"

Broadcom--SDN also amplified the competition between custom vendors and traditional chip makers. Cisco of course mainly applies the self-produced chip, while other Ethernet switch vendors prefer to apply Broadcom or other manufacturers of chips. At the recent Dell Storage Forum meeting, Broadcom architecture and network Cto,nick Ilyadis mainly discussed the status of network software (including SDN) in the current IT system architecture. Read more.

Brocade-it publishes its own development blueprint for SDN, and includes support for OpenFlow and Ethernet fabrics networks.

HP-Announces support for the OPENFLOW,HP network Cto,saar Gillar discusses the SDN ecosystem and reveals that HP is planning to develop OpenFlow controllers to read more.

Dellis expanding its competitiveness in the online market through acquisitions. Dell Network GM Dario Zamarian explains how Dell integrates with SDN to read more.

Juniper Network --Release the latest SDN program

Arista Network -Releasing the latest SDN program

IBM-Release SDN white paper to focus on enhancing IBM network competitiveness

Network Virtualization

In the process of discussing the future form of the network, most vendors put the end point in Sdn. The agreement will no longer be what the user really needs; the need for enterprise it needs to be transformed by technology, training and organizational architecture. Wikibon from Nicira A compelling answer: Nicira is often seen as an SDN start-up because its founders play an important role in the development of OpenFlow, but the Nicira solution focuses on the control plane It is more like server virtualization than network virtualization, which provides the virtualization layer between the application and the physical layer. With the advent of VMware's vmotion, Microsoft's dynamic migration technology, these features also allow the creation of virtual machine pools to be dynamically deployed and migrated. Network virtualization enables this flexibility across a variety of virtual machine management platforms to move any virtual machine anywhere. This feature will have a huge impact on traditional network vendors, not just that the technology will be out of the hardware, but that it can take full advantage of the new physical architecture (like a blade cluster). The three goals of Nicira's network virtualization are, to some extent, a complement to SDN:

• 1. Software and hardware decoupling, two or three-tier data forwarding will be separated
• 2. Redefining Physical and virtual
• 3. Network automation, allowing the operation of flexible

However, most SDN solutions are still in the research and development phase, and Nicira's 24 customers include a number of large networks, telecommunications and cloud service providers (T, EBay, Fidelity, NTT, and Rackspace). Nicira's solution is primarily for large-scale network deployment environments, which is the biggest difference from openflow scenarios. Nicira's Dvni (Distributed virtualized network architecture) builds a network virtualization platform (NVP) that decouples virtual machines from the network through Open VSwitch. The network virtualization technology also applies tunneling protocols such as Vxlan,nvgre or STT (Stateless Transport Tunneling Protocol, Nicira being used, in the IETF drafting phase). When the SDN industry is discussing network transformation, Nicira's perspective has been directed toward the ultra-large-scale next-generation network system.

preparing for the future network

While SDN or network virtualization has not yet reached the desired height, corporate CIOs still need to put these changes into the blueprint for the future of enterprise development. In the years to come, these technologies will help companies transform smoothly from a business model perspective. So, for it practitioners, embracing these technologies is never too early, which enables them to transform themselves rather than be eliminated by them when these technologies come. For network managers, can the "engineer drag the network after the transformation?" "This article understands network transformation from an operational perspective. As Bill Gates understands technological change: We tend to overestimate the changes that have taken place over the next two years, and underestimate the changes that will occur in the next decade. "

SOURCE Link: network revolution: Software-defined networking and network virtualization (Zebian/Wei Wei)

Network revolution: Software-defined network and network virtualization