NVX, Dante and multicast, choosing the right switch.

Choosing the Right Switch for Crestron NVX

Crestron NVX, Dante, and other AV over IP solutions have become mainstream for good reason. These technologies utilize existing infrastructure to their fullest potential, providing exceptional audio and video solutions that span across all locations without the need for extensive cabling, relays, and audio jacks throughout entire floors and rooms. As the quality of video and audio continues to improve and demand for such services grows, the requirements on the IT side have increased. Therefore, IT considerations must be prioritized as the foundation of an excellent AV deployment.

How do you choose the right switch?

1. Bandwidth and Throughput:

   • Gigabit Ethernet Ports: Ensure each NVX device is connected to a gigabit port. For larger installations, switches with multiple gigabit ports or even 10G uplinks are necessary.

   • Port Density: Calculate the number of ports needed based on the number of NVX encoders and decoders plus additional devices (e.g., control processors, touch panels, servers).

     
     

2. Multicast Support:

   • IGMP Snooping: This is crucial for efficient multicast traffic management. It ensures that multicast traffic is only sent to ports that are part of the multicast group.

   • IGMP Querier: In a Layer 2 network without a multicast router, one of the switches must be configured as an IGMP querier to generate IGMP queries and manage multicast group memberships.

   • PIM (Protocol Independent Multicast): In Layer 3 networks, PIM can be used for routing multicast traffic between different subnets.

     
     

3. Quality of Service (QoS):

   • Traffic Prioritization: Configure QoS to prioritize NVX traffic over other network traffic. This ensures that audio and video streams have the highest priority.

   • Class of Service (CoS): Use CoS to classify and manage network traffic by assigning priorities to different traffic types.

     
     

4. Non-blocking Architecture:

   • Switch Fabric: Ensure the switch has a non-blocking architecture to handle the maximum expected traffic without packet loss.

   • Backplane Capacity: The switch's backplane capacity should be capable of handling the aggregate traffic load, especially in high-density deployments.

     
     

5. Latency:

   • Low-Latency Switching: Choose switches with low latency to ensure minimal delay in signal transmission, which is critical for AV applications.

     
     

6. Reliability and Redundancy:

   • Redundant Power Supplies: Select switches with redundant power supplies to ensure continuous operation in case of power failure.

   • Failover Capabilities: Look for features like Spanning Tree Protocol (STP) for redundancy and failover in the network design.

   
   

Calculating Throughput Required

1. Determine the Number of Streams:

   • Count the total number of NVX encoder and decoder pairs.

   • For example, in a setup with 20 encoders and 20 decoders, you have 20 streams to consider.

     
     

2. Calculate Bandwidth per Stream:

   • Each NVX stream can use up to 1Gbps, but typically, the bitrate ranges between 400-800Mbps.

   • Assume an average bitrate of 600Mbps per stream for calculation.

     
     

3. Total Throughput Calculation:

   • Multiply the number of streams by the bitrate per stream.

   • For 20 streams at 600Mbps each: Total Throughput=20×600Mbps=12000Mbps=12Gbps\text{Total Throughput} = 20 \times 600 \text{Mbps} = 12000 \text{Mbps} = 12 \text{Gbps}Total Throughput=20×600Mbps=12000Mbps=12Gbps

     
     

4. Consider Overhead and Redundancy:

   • Add 10-20% for network overhead and redundancy. In this case, 12Gbps + 20% = 14.4Gbps.

Improving Multicast Performance

1. Enable IGMP Snooping and Querier:

   • IGMP Snooping: Configure IGMP snooping on all switches in the network to ensure efficient multicast traffic management.

   • IGMP Querier: If there is no multicast router, enable IGMP Querier on one of the switches to manage multicast group memberships.

     
     

2. Optimize QoS Settings:

   • Marking and Queuing: Use QoS policies to mark NVX traffic with higher priority and ensure it is queued appropriately.

   • Bandwidth Reservation: Reserve bandwidth for AV traffic to ensure consistent performance.

     
     

3. VLAN Segmentation:

   • Separate VLANs: Use VLANs to separate AV traffic from other network traffic, reducing broadcast domains and improving performance.

   • Multicast VLAN Registration (MVR): For larger deployments, consider MVR to allow multicast streams to cross VLAN boundaries efficiently.

     
     

4. Proper Network Design:

   • Hierarchical Design: Implement a hierarchical network design with core, distribution, and access layers to manage traffic flow effectively.

   • Spine-Leaf Architecture: For large-scale deployments, a spine-leaf architecture can provide scalable and high-performance network design.

     
     

5. Firmware Updates:

   • Regular Updates: Keep the switch firmware updated to benefit from performance improvements, bug fixes, and new features. Some device such as Cisco Meraki have an easier firmware update system than other on-prem devices.

     
     

6. Monitor Network Performance:

   • Network Monitoring Tools: Use tools like Wireshark, SolarWinds, or PRTG Network Monitor to analyze and monitor multicast traffic.

   • Performance Metrics: Regularly check performance metrics such as latency, jitter, packet loss, and throughput.

     
     

7. Consult with Network Experts:

   • Professional Guidance: For complex or large-scale deployments, consulting with network experts or the switch manufacturer can provide valuable insights and ensure optimal configuration.

Example Calculation

Suppose you have a network with 50 NVX devices (25 encoders and 25 decoders):

1. Total Streams: 25 streams (one per encoder).

2. Bitrate per Stream: Assume 600Mbps per stream.

3. Total Bandwidth: 25×600Mbps=15000Mbps=15Gbps25 \times 600 \text{Mbps} = 15000 \text{Mbps} = 15 \text{Gbps}25×600Mbps=15000Mbps=15Gbps.

4. With Overhead (20%): 15Gbps+20%=18Gbps15 \text{Gbps} + 20\% = 18 \text{Gbps}15Gbps+20%=18Gbps.

So, you need switches that can handle at least 18Gbps of throughput, preferably with multiple 10Gbps uplinks to accommodate future expansion and redundancy. Lagging or bonding 2x 10Gbps links isn't the same as having a 20Gbps link, always consider a switch with a network module of 20/25Gbps rather than split.

We have expanded in another article on how to configure a Cisco CBS350 switch for NVX and Dante.

By considering these detailed points, you can make informed decisions on selecting the right switch, calculating the required throughput, and optimizing multicast performance for Crestron NVX deployments.