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Designing an EFFICIENT NETWORK INFRASTRUCTURE

Oct 1, 2007 12:00 PM, BY DENNIS M. GLENN

Today’s broadcast workfl ows must be integrated into various levels of operation. Content should be simultaneously available to everyone.

Workflow design has come a long way from the days of the standalone video production system. News outlets of all sizes and post-production facilities demand workflows that are fully integrated into the various levels of operation, making content simultaneously accessible to all stakeholders in a collaborative environment. (See Figure 1 on page 60.) This requires networked digital video systems and effectively managed content, which is not always easy when working with highly sensitive audio and video assets.

The following network infrastructure design goals are fundamental to improving workflow efficiency:

Minimize downtime through redundancy, no single point of failure and the resiliency to recover quickly from a failure of any part of the network, with minimum impact on production;
Maximize network throughput and bandwidth;
Establish architecture for data storage and data path;
Set a high standard for information security;
Tie in all aspects of workflow from ingest to playout;
Allow for the movement of content in any direction;
Enable work in various video formats and resolutions;
Improve tracking and management of audio and video assets;
Facilitate executive review and approval of content in real time via the network;
Enable craft editors to access and work with different parts of a project, such as graphics, title and effects, simultaneously; and
Establish a clear policy for media to be archived.

Figure 1. A logical view of a digital video system and content management network. Click on image to enlarge.

A highly adaptive digital media network is needed to accomplish these goals. The network combines the next generation of IP switching, routing and security infrastructure, with a digital media creation and management solution. The combination provides an integrated, multiservice IT architecture for digital content production and distribution — maximizing workflow efficiency and business continuity.

The network infrastructure will interact with all layers of the production process, including users, applications, metadata, servers and services. Thus, the storage area network (SAN), the type of network switches, security, Ethernet cables and digital asset management (DAM) system should be well thought out during the design phase. (See Figure 2 on page 62.)

The SAN

Figure 2. The network combines the next generation of IP switching, routing and security infrastructure, with a digital media creation and management solution. Click on image to enlarge.

The SAN subsystem has to offer a common view of media resources across the network infrastructure, such as virtualization. It should be designed with a server chassis that has dual integrated switches for redundancy to minimize downtime, easy storage scalability and an open storage networked approach for faster access to content.

The SAN subsystem is the repository for content in a collaborative workflow environment. Therefore, content must be accessible at all times. To achieve this, servers are typically configured with multiple network interface cards (NIC) and dual-homed to the access layer switches for dual connectivity to the content.

Selecting network switches

All gigabit switches are not created equally. The network switches must have the capacity to handle a collaborative workflow with the intelligent movement of high-quality audio and video data across the digital media network, from ingest to playout.

Unlike regular data files, which can be segmented and reassembled, audio and video has to stream sequentially. This requires a network switch with the following features:

Switching capacity of 136Gb/s and throughput of 102 millions of packets per second (Mpps);
Agility and highly advanced, programmable, application-specific integrated circuits (ASICs);
A distributed architecture and throughput;
Optimized features for superior endpoint-to-endpoint performance; and
Wired-speed, nonblocking architecture that offers reliability, availability and security to the network.

All switches connecting to the SAN must have:

Layer 3 capability and 10GigE in order to handle inter virtual local area network (VLAN) routing;
The ability to manage the high level of throughput; and
The proper caching mechanism to handle the oversubscription level — which can be caused by the SAN and video application read and write I/O demand on a switch port.

Oversubscription occurs when the amount of internal switching fabric bandwidth allocated to a given switch port is less than the device connection speed at that port. For example, if a port on a switch has a connection speed of 1Gb/s but is unable to achieve wire-rate 2Gb/s of performance, then the port is said to be oversubscribed.

Routing between VLANs and the corporate network can be implemented by static or a dynamic routing protocol. For the purpose of redundancy, the network should be designed with a minimum of two access switches, and they should be configured with a redundancy protocol such as Virtual Router Redundancy Protocol (VRRP).

VRRP eliminates the single point of failure on the network. It also allows each switch to act as the master router for one VLAN and the backup router for another VLAN. In the event of a switch failure, the healthy switches will become the master router for both VLANs, thus keeping the communication path intact.