This is the first in a series of posts about the SDN-based IP+optical solution oriented to wide area network (WAN) backbone networks. First of all, lets have a look at the new problems faced by legacy WAN backbone networks in the cloud era and examine why WAN backbone networks require IP+optical synergy.

What Are the New Characteristics of Service Traffic in the Cloud Era?

In the cloud era, a WAN backbone network is no longer a relay network between metropolitan area networks (MANs). Instead, it has become a data center bearer network connecting Internet content providers (ICPs) and MANs. The traffic model of a WAN backbone network has the following characteristics in the cloud era:

• Traffic concentrates on connections between large numbers of terminals and a few data centers.

Fierce competition between ICPs often ends up with the winner taking all. As a result, some services are monopolized by a few large-scale ICPs, and the web visits are likely to concentrate on the cloud platforms of these ICPs.

For example, traffic to and from Google accounts for 25% of all web traffic in North America. Because legacy networks are often mesh networks designed for balanced traffic, unbalanced traffic distribution is common in real-world situations.

•    Over the top (OTT) services pose great difficulties to traffic forecast.

In the cloud era, various applications are developed to enrich our digital life. With new applications emerging every day, it is impossible to predict the traffic consumption model and development trend.

A hot TV drama or sports event may cause large-scale changes in network traffic. Legacy WAN backbone networks can hardly keep pace with the continuous increase of emerging services and traffic changes in the cloud era.

What Is the WAN Backbone Network Composed Of?

A WAN backbone network is composed of two layers: IP layer formed by routers and optical layer formed by MS-OTN devices.

Lets have a look at how users access the data center.

After user traffic travels across a MAN to routers on a WAN backbone network, routers perform service and user management and then forward the traffic to MS-OTN devices at the same site.

After the MS-OTN devices send the traffic to a remote optical network in another site, the remote optical network sends the traffic to remote routers for processing. The remote routers, after collecting traffic performance statistics, forward the traffic to DCs.

 

 

Based on the preceding description, we can easily distinguish the roles played by the IP and optical networks.

The IP network focuses on user service processing, whereas the optical network focuses on traffic transmission. The router platform, which possesses strong packet processing and traffic management capabilities, is ideal for user and service management.

The optical network focuses on reducing the cost per bit, improving network reliability, and providing flexible bandwidth services. It carries router services by means of wavelength multiplexing to support large-capacity and long-distance transmission. For the IP network, the optical network is like a high-speed information transmission channel.

What Are the Problems Currently Faced by WAN Backbone Networks?

The IP and optical layers, in terms of planning, operation, and maintenance, have been developing independently for a long time. Carriers have separate departments to plan, design, deploy, and maintain IP and optical networks. Frequent inter-department collaboration results in duplicate investments, low resource usage, and low work efficiency. As a result, backbone networks are hard to deploy and maintain. In general, legacy backbone networks have the following problems:

Difficult Traffic Forecast and Low Network Usage

The exponential growth of traffic imposes tremendous network expansion pressure on carriers. In addition, the escalating growth of cloud computing and OTT service traffic makes it difficult to forecast traffic directions and volumes.

As a result, planned network usage greatly deviates from the actual network usage, networks cannot be flexibly adjusted, and the return on investments is low.

Long Network Planning and Deployment Time and Difficult Network Adjustment

The network planning is complex and time-consuming. Use the three major carriers in China as an example. Network expansion planning usually takes more than one year.

The IP and optical network deployment process is complex and often needs to be adjusted several times. As a result, it usually takes several months to provision a new service.

Inefficient inter-department collaboration and heavy manual workload further add to service provisioning difficulties.

Time-consuming Multi-layer Service Deployment and Low Resource Usage

Due to team separation, limited information sharing, and complex collaboration process, multi-layer service provisioning cannot meet SLA and SRLG requirements.

First, manual planning and deployment result in high OPEX and long service provisioning time.

Second, resource idleness caused by single points of failure results in low resource usage.

The preceding problems increase the length of time required to deploy and provision services, especially those that require high and dynamic bandwidth. As a result, carriers can hardly keep pace with the market.

What Kind of WAN Backbone Network Do Carriers Expect?

In the cloud era, WAN backbone networks have to quickly adapt to the new information consumption mode, reduce O&M costs, and improve customer experience. Only a network model featuring intelligent IP+optical synergy can meet the growing requirements on network performance and management capabilities. Such a network model raises high requirements for WAN backbone networks.

How can we build a WAN backbone network meeting all the preceding requirements?

After extensive research and design improvements, Huawei has developed the SDN-based IP+optical architecture.

This architecture consists of a series of software modules to implement network control, policy management, traffic collection and analysis, service provisioning, network management, and network planning. This architecture also defines a collaboration mechanism between the optical and IP networks. On the control plane, this architecture leverages mature protocols such as PCE and GMPLS UNI to facilitate network deployment.

Because this architecture meets the core concept of SDN, it is named SDN-based IP & Optical Synergy.

In the next post, we will describe the SDN-based IP+optical solution in detail.

Terms:

ICP: Internet content provider. An ICP is a service provider that handles the distribution of online content such as blogs, videos, music, and files.

Waiting for the next post.

@r80048810 : Thanks, stay tuned:)