Implementing Audio-Over-IP from an IT Manager's Perspective

Implementing Audio-over-IP from an IT Manager’s Perspective

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A Partner IT managers increasingly expect AV systems to be integrated with enterprise data networks, but they may not be familiar with the specific requirements of audio-over-IP systems and common AV practices. Conversely, AV professionals may not be aware of the issues that concern IT managers or know how best to achieve their goals in this context. This white paper showcases lessons learned during implementations of AoIP networking on mixed-use IT infrastructures within individual buildings and across campuses.

NETWORKS CONVERGE AS IT such as Cisco and Microsoft. AV experts MEETS AV do not need to become IT managers to As increasing numbers of audio-visual do their jobs, as audio networking relies systems are built on network technology, only on a subset of network capabilities, IT and AV departments are starting configurations, and issues. to learn how to work together. As AV experts come to grips with the terminology Similarly, IT managers are beginning and technology of audio-over-IP, IT to acquaint themselves with the issues specialists—gatekeepers of enterprise associated with the integration and networks—are beginning to appreciate implementation of one or more networked the benefits that AV media bring to their AV systems into enterprise-wide converged enterprises. networks. Once armed with a clear understanding of the goals and uses This shift means that the IT department of these systems, IT managers quickly of any reasonably sized enterprise— discover that audio networking can be commercial, educational, financial, easily integrated with the LANs for which governmental, or otherwise—is they are responsible. now ultimately responsible for the implementation and management of the AUDIO OVER IP: WHAT IT AV systems within the environment. IT MANAGERS NEED TO KNOW managers may even make purchasing Early AoIP technologies were designed to decisions for that equipment, in overcome limitations in bandwidth and a lack consultation with AV experts. of adequate standards for real-time media delivery, resulting in systems that were While AV and IT professionals may deliberately not compatible with data net- understand each other’s technologies well works. Fortunately, those days are long past. enough to interact and collaborate on a project or even on a daily basis, neither Modern AoIP systems such as Dante are is expected to be an expert in the other’s based on common IT standards, enabling discipline. AV experts clearly benefit them to run alongside data traffic on from having a basic working knowledge networks comprised of readily available of IT, and many are availing themselves conventional switches and cables. To the IMPLEMENTING AUDIO-OVER-IP of training and certification opportunities other network members and components, FROM AN IT MANAGER’S 2 PERSPECTIVE from trade bodies such as CompTIA and these audio devices behave like any other InfoComm, as well as from manufacturers node, making implementation, operation, and management of such a network a AoIP systems rely on standards and familiar task to the IT staff. methods that restrict their operation for the most part to LANs, due to the use of multicast for synchronization and discovery. AV experts clearly benefit from having a The IEEE 1588 Precision Time Protocol basic working knowledge of IT. (PTP) is an example of a multicast-based standard that is widely used in AoIP solutions such as Dante. By themselves, multicast protocols are restricted to use STANDARDS within LANs and do not extend to wide While countless standards and common area networks; fortunately, there is no methods exist for many aspects of enterprise functional reason for Dante multicast to networking, AoIP generally relies on a small be shared between subnets, and so this is subset of standards that can easily be easily managed. understood and utilized by IT managers. TCP and UDP Multicast, Unicast, and IGMP An IT specialist observing an AoIP network Snooping will quickly find that large amounts of audio Many network managers are wary of data are sent using UDP instead of the excessive use of multicast, and for good more common TCP. UDP differs from TCP reason. Left unmanaged, multicast traffic in that it does not perform error checking will hit every node on a LAN all the time, or resend data, making it fast and ideal for potentially overloading devices on slower real-time media. This helps the network to link speeds. Contrast this with unicast, in behave well and greatly reduces latency which network messages and data are and error-correction traffic. simply sent from one device to another. QoS (Quality of Service) Multicast is absolutely necessary as a part How do audio networking protocols ensure of AoIP, as it is used to send sync, timing, that time-sensitive data stays “on time” and discovery messages to all devices at when a network is heavily loaded with once. It may also be used to carry audio competing traffic? Standards provide our itself when that audio is going to multiple solution with QoS enabled in switches. destinations simultaneously, and some QoS, which uses priority flags to make protocols rely upon multicast exclusively for sure that audio and timing data are always audio streams, such as the AES67-2015 at the “front of the line,” is commonly high-performance interoperability protocol. implemented in AoIP systems. Note that time is generally only a problem when Knowing that multicast is required, an traffic loads are quite substantial. IT manager can easily configure IGMP Snooping on the switches connected to It should also be noted that the AVB AoIP audio devices. IGMP Snooping ensures protocol requires special “AVB compliant” that only devices that request multicast switches in lieu of using QoS. traffic actually receive it, thus reducing unwanted traffic. IP Addressing IMPLEMENTING AUDIO-OVER-IP While early AoIP (or Audio over Ethernet) FROM AN IT MANAGER’S 3 PERSPECTIVE LANs and WANs solutions sometimes required static IP As the section above explains, real-time addresses, this is no longer the case. Modern AoIP solutions all respect DHCP, AoIP systems add some necessary and most are designed to function perfectly overhead as this data is packetized into well with self-assigned IP addresses as efficient streams. In a Dante network, well, allowing the easy creation of “stand- audio is packaged into UDP audio alone” audio networks where no DHCP “flows” of 4-channels each that consume server is present. approximately 6 Mbits/sec, leading to an easy “rule of thumb” for approximations. Just as with other common network For example, a typical conference room endpoints, DHCP is strongly might require as many as 16 audio recommended. Static IP addresses are channels, for a combined bandwidth rarely necessary in AoIP and are likely to requirement of ~24Mbits/sec, or 2.4% of cause problems due to human error. the capacity of a gigabit link.

VLANs Bandwidth may also be managed with the Virtual Local Area Networks (VLANs) are selective use of multicast. AoIP solutions an easy way to keep traffic segregated such as Dante use unicast UDP for audio while still allowing an AoIP network to flows by default, but when the same share physical infrastructure with an audio channels are being sent to multiple existing IP network. An overload or error devices, unnecessary duplication of data on one VLAN has no effect on the others is occurring. Dante allows audio channels on the same switch. As long as the VLAN to be placed into user-defined multicast has sufficient bandwidth and support for flows, thus eliminating this duplication on a multicast traffic, there isn’t a problem for selective basis. most AoIP systems. REAL-WORLD EXAMPLES AND VLANs are often useful for delineating BEST PRACTICES responsibilities. An AV manager may The examples below illustrate some of the wish to keep traffic on a VLAN in order situations that different AV groups have to clearly define which problems belong encountered and explain how solutions to the AV staff and which belong to the were found, with the help of IT, using IT staff. The downside is this very lack of common tools and methods. integration with the broader network, which may limit some uses of the audio network Using VLANs to Separate Venues at throughout a facility. Fortunately, this is Willow Creek Community Church easily addressed as requirements change. Constraining AoIP traffic within VLANs can provide benefits in management and BANDWIDTH security for audio networks. According IT managers, of course, need to understand to Kurt Donnan, Infrastructure Manager the real bandwidth requirements of AoIP, at Willow Creek Community Church near especially if they are new to the technology. Chicago, where the campus encompasses This knowledge will help them to configure five venues, including a 7,200-seat main systems with adequate headroom in the auditorium, “One of the issues that we most effective manner. had is that each of our multiple venues had to be on a separate VLAN … so IMPLEMENTING AUDIO-OVER-IP The majority of audio used in professional that they weren’t colliding.” The problem FROM AN IT MANAGER’S 4 PERSPECTIVE settings is PCM, sampled at 48 kHz was that the people running audio in one and a bit depth (word length) of 24 bits. venue could “see” the audio devices at the Kurt Donnan, Infrastructure Manager at Willow Creek Community Church, configured the VLANs in the Activity Center to enable wireless communication between the Yamaha mixing consoles and mobile devices running the StageMix controller app.

others, as they shared a common LAN equipment. I had to build a path to land for other purposes. The implementation that access point so that the iPad could of VLANs allowed the AoIP systems at talk to the board.” Solutions of this type, different locations to remain hidden from combining robust security with specific one another. types of access, are easily implemented once IT understands the needs of AV. Using VLANs to Allow Wireless Control at Willow Creek Community Using VLANs to Implement Security Church At the University of Oxford’s Blavatnik Wireless control presents another common School of Government, AV data and AV challenge. As Donnan explains, the control are distributed over two separate centralized Aruba wireless LAN controller VLANs (of a total of 30), enabling strict at Willow Creek Church initially ensured control of access by users and devices. that someone connecting an iPad with “We have a network access control a Wi-Fi access point to remotely control system here, which means we can tag the soundboard would land on the same equipment into two separate networks, subnet as the board. But as the audio whether they are user networks, AV network expanded into the church’s other networks or whatever, and can also restrict IMPLEMENTING AUDIO-OVER-IP venues, he says, “I had to start building access to the AV networks down to our FROM AN IT MANAGER’S 5 PERSPECTIVE VLANs, because we run wireless on IT and AV people,” explains Matt Treavis, different subnets than our wired audio Head of Information and Communication Technology. Robust data security is and on schedule. “If anybody was talking to essential in a facility that has hosted me about doing a converged network I would conferences and events with the likes make sure that the AV people understand of the Duke of Cambridge, former UN the specifications of the AoIP protocol and Secretary-General Kofi Annan, and other that they have access to them. Having those major political figures, Treavis says. conversations quite early would be good.”

In the case of the Blavatnik School of “If anybody was talking to me about Government, the AV supplier built the network offsite because of restricted doing a converged network I would access during the building’s construction, make sure that the AV people Treavis says. “If you’re doing that then you can end up with a situation where, when understand the specifications of the you bring it into the live environment, you AoIP protocol.” run into problems with access control lists – Matt Treavis, Head of Information and Communication Technology and other bits and pieces that need some further diagnosis between the AV and the IT guys,” he cautions. “People do need Using Existing Ports for Audio to think about the cultural differences Everywhere between IT and AV and how they plan for Anyone implementing an AV network it, and maybe get that sorted out up front.” as part of an enterprise-wide mixed-use infrastructure should consider the key CONCLUSION benefits of a converged network, says While Oxford University and Willow Creek Treavis. “We have about 2,000 ports, and Community Church are quite different in every port in the building is live, so we have terms of the scope of their IT and their the flexibility to route AoIP data anywhere work cultures, they share a common in the building.” As a supplement to the platform of tools and capabilities through installed AV systems, additional equipment IP networking standards that allow each to can be set up and quickly configured in any deploy AoIP in a manner that suits distinct space within the facility. “If you have data needs and concerns. points flooded throughout the building, and all of your VLANs are presented on every As AV moves toward networking as switch cabinet, then you have that ultimate a commonly accepted practice, AV flexibility,” he says. “We can go anywhere professionals and IT specialists will find that there is a data point and we know we themselves working together more closely. can make it work.” People coming from AV will develop a toolkit of networking skills, and those in IT Best Practices: Planning around will become familiar with the needs of AV Differences between IT and AV services Both parties have a vested interest Treavis, who came to work at the school from in success for the enterprise. Fortunately, a corporate IT environment shortly before the development of audio networking the present AV system went live, stresses on top of robust standards means that that thoughtful planning and conversations technical barriers are few in number, and IMPLEMENTING AUDIO-OVER-IP between IT and AV can go a long way toward only a mutual understanding of goals is FROM AN IT MANAGER’S ¢ 6 PERSPECTIVE making the final commissioning go smoothly required to overcome those obstacles.