Multi-CDN Best Practices for Optimizing Performance and Reducing Latency
Pursuing a multi-CDN strategy is critical to reliable and high-performance edge delivery when streaming at scale to disparate audiences in multiple regions. But what do large-scale streamers need to know about multi-CDN decisioning and traffic-shaping to optimize performance? Corey Behnke, Producer & Co-Founder, LiveX, discusses this topic with Sean McCarthy, Principal Product Manager, Technical, Paramount, and Jeff Gilbert, VP, Content Delivery Services, Harmonic Inc., in this clip from their Streaming Media East 2023 panel.
Behnke begins by asking McCarthy, “How does your platform handle traffic management and load balancing across multiple CDNs or regions? Can you explain the approach or strategies used to optimize performance and minimize latency?”
“We have a homegrown solution,” McCarthy says. “It's based off of existing technologies like an NS1 Pulsar or Cedexis or Citrix traffic manager. And so far we use Real User Monitoring (RUM) data that's really based off test object downloads, but we wrote our own RUM client, so it exists on all of our web properties. So, cbs.com, cbsnews.com, paramountplus.com…when a user loads the page, we'll essentially compile a tasks runner and the browser download a bunch of 1.5 MG objects. And then we have performance beacons that we aggregate, and we stack rank CDN performance at the state or country and ASN, some geo and some ASN denomination and forward those to either a DNS provider, which makes our platform very much like a Cedexis or NS1. But we also will forward them to our manifest generation service and do decisioning or traffic shaping in the manifest. And pretty soon we'll be forwarding them to a HLS and DASH content steering service to do the enforcing of the decisions right in the client.”
“How many CDNs?” Behnke asks.
“Too many!” McCarthy jokes. “We're a large company and we are the result of several mergers. And every company came with their own legacy CDN workflows. So we're trying to narrow down the list of vendors, but we're actively sending traffic to seven, and I think that the majority of the traffic is on four of those vendors. So it's kind of our goal to agree on four going forward.”
Gilbert says, “It's a tremendous approach that you're taking, and it saddens me that that's necessary. I think the interesting conversation is, why is there such disparity? You've got infrastructure [where] in many cases the CDNs all have caches effectively sitting in the same data centers with effectively the same connections to end users. And you're like, ‘Okay, how is it that one's outperforming the other, they're based off the same original software.’ I think that ultimately the fact that you have to jump through those hoops is one of the issues in the CDN industry as a whole.”
Gilbert further elaborates on the present inefficiencies of the CDN industry and the complexities faced attempting to streamline the systems. “I think CDNs are troubled, and I think one of the elements is the burden on the content publisher,” he says. “You have to spend a lot of time and resources to navigate this disparate group of CDNs that aren't performing as they're supposed to. And I think that's because there's a lot of elements in the content delivery chain. You've got content being cached effectively at internet exchange point (IXP) level, and there's a whole host of infrastructure between them and the end user. And so something's getting hijacked in the middle that's causing you to say, ‘Oh, the performance is bad. Is it the digitor, the cable modems? It's called the CMTS, the Cable Modem Termination System. It's what your cable modem talks to.”
Gilbert emphasizes that the critical challenge is how to get large amounts of data down an existing pipeline and how to do it economically. “That's the hat I've been putting on for this whole conference,” he says. “Okay, great, you come up with a technical solution, but if it doesn't make sense from a business point of view, which is what you're talking about, then you don't really have a solution at all. And so, virtualizing that, we have something called the virtual CMTS.
“And so now you're saying, ‘Okay, what used to be racks and racks of pizza box kinds of solutions now becomes Linux boxes running Kubernetes with applications running inside of them. So you can easily scale up and down as demand changes. You get a very popular game, you're going to send a lot more data down, and so you're going to need more processing. You just spin up more resources. It's very sort of cloud-like, which people are accustomed to. And so converting over from a physical hardwired solution to one that's more of a software solution is something that's giving cable companies a lot of flexibility and the ability to offer services much more cost-effectively. Not just price effective, but they're actually reducing their costs, giving them the ability to actually add more capacity without having to go to the bank and buy a whole lot more boxes. So ultimately, that's how we're helping people handle getting more content down the last mile, we're reducing the cost of it. And that's…really a changing kind of situation where [it’s], ‘Okay, let's just send more data because we can do it cheaply.’”
Learn more about CDNs and a wide range of streaming industry topics at Streaming Media Connect 2023.
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