Implementing Audio-over-IP from an IT Manager’s Perspective Presented by: 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.