Software defines the role of the network in cloud computing

There are two http://www.aliyun.com/zixun/aggregation/13868.html in cloud computing "> software defines the network model and two different SDN tasks, because the network creates the cloud, Managing the interplay between these two aspects is the key to cloud success.

As an information service, the Internet sees the network as a transparent partner. In the cloud, a user's application is in the clouds and becomes a part of the cloud. Most people think that at least some networks must be integrated with the cloud. The current work is that the data center must make the cloud concrete, but should the WAN be the "resource" of the cloud?

In cloud computing, users join a community created by a cloud. Cloud computing service providers face a multi-tenant problem at the network level, similar to the multi-tenant problems they face at the CPU server and database level. Shared resources must be shared in a way that a user's application cannot affect the application of another user, so all user resources must be partitioned to determine their privacy and security. At the same time, network technologies, such as IP and Ethernet, each have virtual network capacity, which is limited by the number of tenants that can be supported, limiting the separation of tenants.

The cloud software provider sees the network as a partnership between the data center network and the cloud. The flexible IP address application-driven approach of Amazon Web services consolidates networks and clouds; OpenStack includes network services as one of the virtualized resources, along with storage and CPU servers. For example, the OpenStack Quantum interface defines how a virtual network can be created as a "managed" CPU and database element. However, Quantum does not define the technology that users create this virtual network. Each vendor is responsible for mapping its technology to the virtual network model defined by quantum.

Two SDN models of cloud computing

First of all, adjust the multi-tenant, and then support the network Services cloud control requirements will bring us to the SDN technology. The two models of SDN appear: Overlay model (Overlaymodel) and network Model (Networkmodel).

In the overlay model, software (usually cloud-connected software) creates a virtual network in which network devices create these virtual networks.

Overlay SDN, such as VMware's recently acquired Nicira Technology, uses software to partition IP or Ethernet addresses into multiple virtual subnets, similar to what TCP does to ports. A new set of network APIs allows applications to access these subnets through their IP or Ethernet network. The software ensures the security and separation of multiple subnet traffic. Network devices "See" Do not overlay virtual networks, and therefore do not discriminate traffic.

Network-hosted SDN are built with network devices; Therefore, they directly manage SDN traffic. Some network vendors, such as Cisco, create "revolutionary SDN" by adding software control to current devices and networks using current SDN-compliant network technologies and devices.

Other network vendors, including most SDN start-ups, want to develop network devices in a simple form, migrating routing intelligence and Path/traffic management, all in devices and concentrating on cloud-hosted software.

But overlay and network models and tasks conflict across WANs. If cloud virtual networks must extend additional cloud data centers and outward users, it is difficult to see how virtualized network-hosted SDN implementations can be circumvented for three reasons:

Overlay SDN relies on software elements to create virtual networks. It is difficult to ensure that users request software to participate. You cannot use overlay virtualization when software on a network device cannot be easily updated.

Overlay SDN does not ensure WAN quality of service (QoS) because SDN cannot manage traffic out-of-the-box. The network managed SDN can provide the same exact interface and service as the user used before, and the request for software or service has not changed. Also manages traffic and guarantees QoS. Therefore, the End-to-end SDN task favors the SDN model implemented in the network.

The increasing adoption of SDN as a "cloud network" means that the transformation of networks and services can support a wide range of cloud computing use. Manipulating various SDN tasks and technology models is the right place for cloud services and the key to achieving cloud computing benefits. For cloud users, knowing the SDN plans of their cloud providers, as well as the plans of private cloud software stacks, is the key factor in ensuring the long-term value of these providers.

(Responsible editor: The good of the Legacy)