Cisco Catalyst 9300 Series Switch: Настройка аудио-видео мостирования (AVB)

Information about Audio Video Bridging

Configuring Audio Video Bridging The following sections provide information about various aspects relating to audio and video bridging networks. Restrictions for Audio Video Bridging Networks, on page 1 Introduction to Audio Video Bridging Networks, on page 1 How to Configure the Audio Video Bridging Network, on page 6 Monitoring the Audio Video Bridging Network, on page 15 Examples of Audio Video Bridging Configurations and Monitoring, on page 17 Feature History for Audio Video Bridging, on page 38 Restrictions for Audio Video Bridging Networks • AVB is not supported on stacked systems. • AVB is not supported on EtherChannel interfaces. • AVB is supported only on STP-enabled network.

• The maximum number of MSRP streams supported is 200 in one device. • The C9300-48HX, C9300-48TX, C9300-24HX, C9300X-48HXN, C9300-24UX, C9300-48UXM, C9300-24UXB, and C9300-48UN switch models do not support gPTP at 100Mbps speed. Introduction to Audio Video Bridging Networks Information about Audio Video Bridging Audio and video equipment deployments have traditionally been analog single-purpose point-to-point one-way links. Migration to digital transmission also continued to retain the point-to-point one-way links architecture. The dedicated connection model resulted in a mass of cabling in professional and consumer applications, which was hard to manage and operate.

In order to accelerate the adoption to Ethernet based audio/video deployments in an interoperable way IEEE came up with the IEEE Audio Video Bridging standards - IEEE 802.1BA. This defines a mechanism where endpoints and the network will function as a whole to enable high quality A/V streaming across consumer applications to professional audio-video over an Ethernet infrastructure. Configuring Audio Video Bridging 1

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Components of Auio Video Bridging Network

Note • AVB is not supported on stacked systems. • AVB is not supported on EtherChannel interfaces. • AVB is supported only on STP-enabled network. Audio Video Bridging License Level Audio video bridging is supported on the Network Advantage license. Benefits of Audio Video Bridging AVB is a mechanism to enable Ethernet based audio-video transmission which has the following benefits: • Guaranteed max latency • Time synchronized • Bandwidth guaranteed • Professional grade Components of Auio Video Bridging Network AVB protocols operate only in domains where every device is AVB capable. The AVB network comprises of AVB talkers, AVB listeners, AVB switches and the grandmaster clock source.

• AVB Talker - An AVB end station that is the source or producer of a stream, i.e. microphones, video camera, and so on. • AVB Listener - An AVB end station that is the destination or consumer of a stream, i.e. speaker, video screen, and so on. • AVB Switch - An Ethernet switch that complies with IEEE802.1 AVB standards. • AVB stream: A data stream associated with a stream reservation compliant with the Stream Reservation Protocol (SRP). In some instances, the word “bridge” is used. In this context, it references to a switch. Note The IEEE 802.1BA specification requires that an AVB talker must be grandmaster capable.

In a typical deployment a network node can also be the grandmaster, provided it can either source or derive timing from a grandmaster capable device and provide the timing to the AVB network using IEEE 802.1AS. Figure 1: AVB Network shows a simple illustration of AVB network with different components. Configuring Audio Video Bridging Audio Video Bridging License Level Configuring Audio Video Bridging 2

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Components of Auio Video Bridging Network

Figure 1: AVB Network In many instances, the Audio/Video end points (Microphone, Speaker, and so on) are analog devices. AVB end-point vendors introduce Digital Signal Processors (DSP) and I/O devices that provide extensive audio/video processing and aggregate the end-points into an AVB Ethernet interface, as shown in Figure 2: Vendor Audio I/O System, on page 3 . Figure 2: Vendor Audio I/O System Configuring Audio Video Bridging Components of Auio Video Bridging Network Configuring Audio Video Bridging 3

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Information about Multiple Stream Reservation Protocol

Supported SKUs for Audio Video Bridging All Cisco Catalyst 9300 Series Switches support PTP or AVB on all ports (both uplink and downlink ports) except as listed below: • C9300-48UXM: Supported on 1 to 16 downlink ports only and all uplink ports. • C9300-48UN: Supported on 1 to 36 downlink ports only and all uplink ports. Information About Generalized Precision Time Protocol Generalized Precision Time Protocol (gPTP) is an IEEE 802.1AS standard, which provides a mechanism to synchronize clocks of the bridges and end point devices in an AVB network. It defines the mechanism to elect the grandmaster clock (BMCA) among the time-aware bridges and talker and listener.

The grandmaster is the root of the timing hierarchy that gets established in the time-aware network and distributes time to nodes below to enable synchronization. Time synchronization also requires determining the link delay and switch delays in the network nodes. A gPTP switch is an IEEE 1588 boundary clock, which also determines the link delay using the peer-to-peer delay mechanism. The delays computed are included in the correction field of the PTP messages and relayed to the end-points. The talker and listener use this gPTP time as a shared clock reference, which is used to relay and recover the media clock. gPTP currently defines only domain 0, which is what the switch supports.

The peer to peer delay mechanism runs on STP blocked ports as well. No other PTP messages are sent over blocked ports. In a PTP domain, Best Master Clock (BMC) algorithm organizes Clocks and Ports into a hierarchical fashion, which includes clocks and port states: Clocks • Grandmaster (GM/GMC) • Boundary Clock (BC) Port States • Master (M) • Slave (S) • Passive (P) Information about Multiple Stream Reservation Protocol Multiple Stream Reservation Protocol (MSRP) provides a mechanism for end stations to reserve network resources that guarantee the transmission and reception of data streams across a network with the requested QoS.

It is one of the core protocols that are required on an AVB device (talker, listener, and switches). It allows talkers to advertise streams across a network of AVB switches and listeners to register for receiving the streams. MSRP is the key software protocol module for supporting AVB. It enables stream establishment and teardown. It interfaces with gPTP to update the latency information for the streams. It interfaces with the QoS module to setup the hardware resources that would guarantee requested bandwidth for the streams. It also provides the QoS shaping parameters that are required for the credit based shaper.

Configuring Audio Video Bridging Supported SKUs for Audio Video Bridging Configuring Audio Video Bridging 4

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