Review: Netgear M4250 Network Switch
In April 2016, NewTek released NDI version 1.0 as a way to send audio and video signals over gigabit Ethernet. The NewTek TriCaster was the first device to support this protocol, and over time, support for NDI has increased to read like a who’s who of the video production world.
Some of the key companies that produce official NDI products are listed at NDI Marketplace. The products include PTZ and box cameras, mobile applications, video switching software, encoders and decoders, displays, audio solutions, graphics, and more from names like NewTek, Panasonic, Canon, BirdDog, PTZOptics, Sony, JVC, HuddleCamHD, Marshall, Datavideo, Ikan, Magewell, Teradek, Kiloview, Deltacast, Netgear, and vMix. I’m not sure what qualifies a piece of software or gear as an “official NDI product,” but off the top of my head, I’m aware of other companies that make products for the NDI ecosystem that aren’t listed in NDI Marketplace, including OBS, XSplit, Chyron, Vizrt, Microsoft Teams, and Zoom.
In most categories of products, there are several options to choose from, and a lot of attention is paid to the NDI video cameras, virtual meeting services, and NDI encoders on the acquisition end of the workflow. My own NDI workflows consist of Canon CR-N500 PTZ cameras and Microsoft Teams for acquisition.
The NDI video switching system used to mix, stream, and record a program is also a very important workflow consideration that deserves as much attention as is paid to the NDI acquisition devices. I use vMix for my software video switching, streaming, and recording needs, regardless of whether the inputs are SDI, HDMI, or NDI.
Decoders are also important for sending live video to projectors and monitors at a venue. I’m still in the testing phase with a BirdDog Play that took 11 months to arrive. I’m hoping it proves to be a viable alternative to sending video over SDI when I need to power a projector, a comfort monitor, or secondary screens at a venue.
Managed Network Switch
Of all of the components that form part of an NDI workflow, the one that often is treated as an afterthought is a managed network switch. Perhaps one of the reasons for this is that for many producers—me included—the thought of mastering another skill can be intimidating. We are already expected to provide expertise in video cameras, switchers, live streaming, audio, and wrapping cables using the over-under method. How are we now going to master the advanced network management requirements of NDI?
The answer to this is very simple: Start with the Netgear M4250 AV line of switches (Figure 1, below). If you need a further reason to start and end your search with this one product out of all the products in the entire NDI ecosystem, just consult the NDI Marketplace and you will see that the Netgear M4250 is the only option listed under Network Products. Sure, you can configure other managed switches to work with NDI workflows, but you will have to navigate a user interface designed for network management, and that will differ depending on the manufacturer and model.
Figure 1. Netgear M4250 network switch
AV User Interface
The Netgear M4250 has two UI options: the Main UI and the AV UI. The AV UI makes it easy to set up an NDI network and to even use the same switch for both segmented internet and NDI traffic. If you have networking experience and skills, you might have success setting up your NDI network on a different switch by following the Networking Best Practice-White Paper guide and searching for an archived copy of “NDI Network Guidelines.” (The latter is a NewTek document dated from 2018 that is easy to find online, but because it is several years old and marked “Confidential—Internal and Reseller Use Only—Do Not Distribute,” I am not going to directly link to it since I’m not even sure if the settings are recommended in current NDI 5 workflows.) Ultimately, because the Netgear M4250 is the de facto standard that the industry is adopting, using a different solution means your peer base for support is going to be tiny.
The other challenge of following the two documents for your own switch configuration is that while they will help guide you to disable jumbo frames and QoS settings, you’ll still need to make decisions for most of the settings discussed in “Networking Best Practice-White Paper,” like choosing between Reliable UDP, Multipath TCP, or Single TCP or UDP with Forward Error Correction. This probably goes beyond what most video professionals are comfortable doing, because it doesn’t tell you which one to select as a default and instead explains all of the options and leaves it up to you to select the correct one for your use case.
I liken this to being tasked to bake 500 chocolate chip cookies without an actual recipe but with a fully stocked pantry that has every option imaginable: flour, fat, sugar, eggs, leavening agents, and chocolate chips. To make matters worse, your only measuring device is a scale, and instead of a recipe, you have a food science book that goes into detail about all of the ingredients and techniques that you can use in different recipes. Eventually, you would probably be able to develop your own recipe by calling on your past experiences eating cookies and the one time over the past year that you helped your kid bake cookies using a recipe they wanted to try that they saw on TikTok—except those were for gluten-free sugar cookies, you substituted the almond flour for rice flour, and the cookies were so bad that you needed two glasses of milk to wash them down.
I think you get the idea: Too many options and a lack of a tried-and-true recipe aren’t a good starting point for cookies or setting up an NDI network. Setting up the M4250 for an NDI network is a simple as connecting a computer to an Ethernet port or out-of-band (OOB) port on the switch, logging into the AV console, selecting the NDI preset for the ports you want to connect your NDI devices to, and then connecting the devices—all while knowing that your NDI network is going to be configured properly and quickly.
Bandwidth
When selecting an NDI switch, you need to consider bandwidth, port segmentation, and port-based profiles. Bandwidth is important in an NDI workflow because for you, your video is priority traffic, and you don’t want it delayed or dropped. Too much bandwidth, and you can saturate the network. Most corporate networks, like shared website hosts, are over-prescribed to the degree that they expect each connected user to consume bandwidth in small bursts and infrequently. Activities like checking email, uploading a few photos as part of social media posts, and researching better cookie recipes don’t require a steady stream of bidirectional traffic. If a bit of latency is introduced because the network is overloaded, it won’t dramatically affect the user experience. Because of the sustained throughput needs of NDI video and the burst needs of data traffic, it is best practice to segment your NDI traffic from your data and internet connection.
NDI bandwidth requirements range from 16Mbps for an NDI|HX 1080 60p signal to 350Mbps for a full NDI 4K 60p signal. NDI uses a protocol called Internet Group Management Protocol (IGMP) for multicasting. This is different from unicasting, which is a 1:1 connection, and broadcasting, which is 1 to every other host on the network. Broadcasting works in theory but will quickly flood a network.
With multicasting, only the hosts that want the video stream will receive it, so you aren’t sending video signals to a video camera that is also broadcasting and has no use for incoming video signals. In order to deploy multicasting, the switch needs to support IGMP snooping and IGMP querier. In some implementations, the snooping and querier functions are performed on two different switches, but the Netgear M4250 has both, which makes implementation much easier. Netgear’s instance of IGMP is called Netgear IGMP Plus.
You also want to avoid using an unmanaged switch on an existing network, as all you are doing is connecting devices to a managed network that is already configured and may or may not work for your NDI workflow. The worst part is that this might work well enough in internal testing at your studio on your own network, but the moment you take it to a client location, hotel, or conference center, you are at the mercy of the restrictions on the network you are joining.
If you want to guarantee that your NDI network is going to work reliably, you need to manage it yourself. One of my first big lessons when I started working with NDI was that I didn’t have to depend on the network of the location I was working at for my NDI devices. This is a good thing, as I already found it frustrating enough working with hotels to gain a simple internet connection for a hardware webcast encoder that couldn’t browse to a website and accept the terms of service or enter a password. Ultimately, I stopped trying to use hardware encoders and moved to laptop-based encoders with vMix software. The point is that if I wanted consistent results, I needed to set up my own network to connect my NDI devices to.
Port-Based Profiles
With a managed switch, I can set up my own private network that doesn’t interact with the venue’s public internet network. On the Netgear M4250, this is done by using the port-based profiles to designate different presets (NDI and Data in my case) to two different groups of ports and creating an additional virtual local area network (VLAN) to segregate the NDI traffic from the data traffic (Figure 2, below).
Figure 2. NDI 5 profile template applied to ports 1-6 with a static IP address and segregated VLAN
The Netgear M4250 VLANs can assign the same static or DHCP IP addresses that the NDI devices and data connections require. I still need access to the internet for my live streams, but that is solved by adding a second network interface controller (NIC) to my computer. One connects to my NDI network—and in my workflow, I assign static IP addresses—while the other is set to DHCP for internet for the internet connection. This controller could be configured to a static IP if required.
Working across two VLAN networks gives me the bandwidth control and port-based profiles I need on the NDI network for my video and audio traffic and ensures that the data traffic on the existing network is a separate consideration that won’t interact with my signal flow.
There are a variety of different options for adding a second NIC to a desktop/workstation system or laptop computer. I spec all of my workstations with two on-board NICs because I find they work well with my Blackmagic Design hardware-based workflows. But I have also added PCIe NICs to some systems in the past. For systems lacking the ability to add a PCIe NIC, my go-to NDI pairing is the CalDigit TS3 Plus Thunderbolt 3 (TB3) dock on my TB3-equipped laptop webcast encoders. I also have a touchscreen laptop that I use with a simple USB 3.0-to-Ethernet dongle. I pair a Behringer XR18 digital audio mixer with that laptop, which (I’m embarrassed to admit) I purchased without realizing that it didn’t have a single Ethernet port.
Within the AV UI, you can control the fan setting (off, quiet, cool). Normally, I have this set to quiet for use in venues where the noise floor is not particularly quiet to begin with and the switch is out of sight under a draped tech table. I’ve also found this setting really convenient for use in my own studio when the switch was on my desk and the fan’s whine could be heard in the otherwise quiet room.
Power over Ethernet
Power over Ethernet (POE) refers to sending power over the Ethernet cable. The M4250 line has models that support POE+ and POE++ standards. POE+ can deliver 15.4 or 30 watts (W), and POE++ adds 60W, 75W, and 90W power delivery options. One of the benefits of POE is that you can power devices like your PTZ cameras with a single Ethernet cable, which means fewer cables and power adapters compared to running AC power to a DC transformer and an extension cord and video cable.
The other benefit is that you have centralized power control, which means you can power up and down your POE devices by simply powering down the switch. On the M4250, you can activate or disable POE delivery on a port-by-port basis (Figure 3, below). I have POE turned off on the data VLAN ports. Technically, I could turn it off for ports on my NDI VLAN that I know will always be connected to a laptop NIC and not a POE camera, but I don’t need to because the 802.3af and 802.3at standards supported by the M4250 line have automatic detection and won’t send power unless it is required. This is not the case with POE injectors and switches with passive POE power.
Figure 3. POE power management on ports 1–6 showing three POE+ PTZ cameras consuming 36W, two NDI devices not receiving POE+ power, and one available POE+/NDI 5 port. Ports 7 and 8 have POE disabled.
Netgear M4250 Line
The Netgear M4250 line has more than a dozen different models. The form factors include desktop, 1RU, and 2RU rackmount options. Each switch has its own processor, RAM, and IEC connector with an internal power supply.
The GSM4210PD Desktop and GSM4212P 1RU models retail, respectively, for $600 and $610 and are equipped with 8x gigabit Ethernet POE+ (30W) ports, 1x or 2x gigabit SFP ports, a 20Gbps or 24Gbps switching capacity, and a total POE+ budget of 110W or 125W (Figure 4, below). My Canon N500 PTZ cameras consume up to 19.6W of POE+ power, so I could power five or six cameras using these entry-level switches. If you need to power more cameras, there are additional models in the M4250 POE line for higher input and power budgets.
Figure 4. Ethernet I/O on the Netgear M4250 GSM4212P
Using the more power-hungry Canon N700, BirdDog P4K, or Panasonic AW-UE150K POE++ cameras changes the minimum requirement to an M4250 model that supports 90W POE++ and has a higher power budget. The GSM4212UX $1,200 model is similar to the GSM4212P but supports POE++ power with a total budget of 720W and a 60Gbps switching capacity.
The higher end of the line features models with even higher power budgets, with 24 and 40 POE ports, including the $4,690 GSM4248UX 40-port POE++ model with a 2,280W budget and three IEC power connectors.