Newsletter: AV Pro Tricks

May, 2023

By Tony Torres, Technical Support Engineer III

Pro AV Tricks with Tony Torres, Technical Support Engineer III

Tony Torres, who recently joined ZeeVee as technical support engineer (III), has an extensive integrator background. He is very adept at finding solutions that enable our ZyPer4K and ZyPerUHD encoders and decoders to work at optimum performance and reliability with any network switch. He provides a peek at his skills by offering a 10,000-foot level overview of how he has enabled our encoders and decoders to work with Cisco network switches. His approach can be adapted to other network switches. SIGNAL Partner integrators have the option of leveraging Tony’s expertise when configuring network switches and preparing complex installations.

Network switch manufacturers, including Cisco, Juniper, Extreme, Arista and Netgear, have provided the means to distribute IP content for more than 25 years. Each has developed lists of gear that approach this task differently, with each model having its own parameters and nuances. Because of this, some switches are not completely ready to work out-of-the-box in the AVoIP ecosystem without mindful preparation and configuration on the part of integrators.

Cisco switches and AVoIP (Audio-Video over IP) systems can face compatibility issues due to the use of the Internet Group Management Protocol (IGMP) and the querier device. While a querier is required for Cisco switches to interface with IGMP, it can become problematic for AVoIP systems. This is because the querier requires every packet of content to be routed through it before directing it to the desired video decoder. While this is not an issue for general IT or multicast applications, it can cause problems for AVoIP systems where video content packets can be as large as 400 megabytes. This limits the maximum number of video packets a single gigabyte switch can handle at one time, which can be a deal-breaker for most users.

To better understand this issue, it is important to know that there can be only one querier per network. Therefore, having more than two switches that send data to the querier causes the network to ‘break,’ creating a catch-22 situation for integrators. The querier is required for the IGMP network to function, but it also limits the system's scalability, creating problems for users.

To tackle this problem, I delved into the realm of PIM multicast routing and VLANs and came up with a solution to create a highly segregated system. The approach involved setting up separate VLANs and using layer 3 routing to connect the two switches. PIM multicast routing was then employed to allow all devices and components to communicate with each other seamlessly. PIM multicast routing is an underutilized methodology in the networking world and few AV and IT professionals are familiar with it. However, it played a crucial role in solving the compatibility issues and creating a reliable Cisco switch-driven AVoIP system.

The first step was to create a "bubble" for each switch or switch stack. This involved assigning each switch its own VLAN and querier, as well as a separate VLAN to connect the switches. By doing so, the endpoints could communicate only with the devices connected to their own switch, creating a hyper-segregated system. However, while this approach solves reliability, it limited the larger network's functionality. Therefore, the next step was to create a routing mechanism to allow all devices to communicate with each other.

To enable PIM multicast routing, an underlying layer 3 routing protocol is necessary. To create a reliable network within my lab, I utilized the Open Shortest Path First (OSPF) routing protocol. With this in place, network packets can be elevated from layer 2IGMP to layer 3 PIM multicast routing, enabling them to travel freely between the two Cisco switches and any designated AVoIP encoders or decoders. By combining the OSPF routing protocol with PIM multicast routing, I was able to create a network that provided seamless communication throughout the system. This approach allowed me to overcome the limitations of the hyper-segregated system while maintaining its reliability.

However, the use of IGMP and the querier device in Cisco and other non-preconfigured switches can cause compatibility issues for AVoIP systems. These problems can be overcome by employing PIM multicast routing and segregated VLANs. With proper planning, it is possible to create a scalable and reliable system that meets the demands of AVoIP applications.

Of course, just like we have our own great support team, any detailed questions about third-party gear should be directed to that vendor.

If you have any further inquiries you would like to discuss in more detail, require examples, or need assistance with technical issues, please feel free to contact us at