Moving video production to IP has been ongoing for over 5 years using both SMPTE ST 2022-6 and now ST-2110 but we’re still in the ‘Early Adopter’ phase, explains the Willem Vermost speaking at SMPTE 2019. Willem is the EBU topic lead for the transition to IP-based studios and he is tracking the upcoming projects with public broadcasters.
Willem talks about what’s motivating these Early Adopters. In general, he explains, they have a building move project and they are faced, as CBC (Canadian Broadcasting Corporation) was, with being the last to install an extensive SDI infrastructure – and be stuck with that for 7, 10 or more years to come – or the to be one of the first to use IP. Increasingly, they can’t justify the SDI workflow and IP, for all its risks and uncertainties, is the way forward.
CBC/Radio Canada needs to be ‘on air’ in 2020 so they put in a place a risk mitigation plan to test all the equipment before putting it in. Willem outlines what this test plan looks like and what it covers: AES67, ST 2110-40,-7, -30-, -20, EBU r148 security etc. Testing was also brought up by the BBC’s Mark Patrick when he discussed his work in bring in the BBC’s Cardiff Square building on-air. They found that automated testing was key in project delivery so that testing was quick and consistent to ensure that software/firmware patches were correctly accepted into the project.
Willem talks us through the EBU’s famous Technology Pyramid which shows to what extent each of the technologies on which media-over-IP requires has been defined and adopted by the industry. It shows that while the media aspect has been successfully deployed, there is a lot to do in, for example, security.
Difficulties arose due to different interpretations of standards. To aid in diagnosis of such issues, the LIST project has created a 2110 analysis tool and other related tools. This is created within the EBU and Willem highlights some key parts of what it does. He then shows how that connects in with the automated test programs and explains the underlying structure of how the software is built.
The talk finishes with mention of the JT-NM test plan, a summary and questions lead by Arista’s Gerard Phillips.
Leaf & spine networks have started taking over data centres in the last few years. It’s no secret that people prefer scale-out over scale-up solutions and you can see a similar approach in ST 2110 networks, when large monolithic video switches are replaced with smaller leaf and spine switches.
Leaf and spine refers to networks where a number of main, high throughput switches link to a number of smaller switches. These smaller switches tend to be aggregators and offer the promise of cheaper ports delivered closer to your equipment. The alternative to leaf & spine is monolithic switches which do have their merits, but are certainly not always the right choice.
To provide non-blocking switching in leaf & spine networks you need an SDN controller that orchestrates media flows. Advances in SDN capabilities have led to the emergence of “Purple” network architectures. In this video Gerard Phillips from Arista shows how it differs from a “Red/Blue” architecture, how path diversity is maintained and how ST 2110 IP live production or playout applications could benefit from it.
It’s important to be aware of the different uses of Layer 2 vs Layer 3:
• Layer 2 devices are typically used for audio networks like Dante and RAVENNA. A layer 2 network is a simple, scalable and affordable choice for audio flows where there are no challenges in terms of bandwidth. However, this type of network doesn’t really work for high bit rate live production video multicast since all multicasts need to be delivered to the IGMP querier which isn’t scalable.
• Layer 3 have distributed IGMP management since PIM is used on each router to route multicast traffic, so there is no more flooding network with unnecessary traffic. This type of network works well with high bit rate video multicasts, but as IGMP is not bandwidth aware, it’s best to use an SDN system for flow orchestration.
Gerard then looks at resilience:
Using 2022-7 seamless switching (plus a robust monitoring system that can provide quick, accurate information to resolve the issue)
Providing redundancy (redundant PSU, fans, fabric modules etc., redundant links between switches, ensuring that routing protocol or SDN can use these “spares”)
Dividing up failure domains
Using leaf and spine architecture (routing around failed components with SDN)
Using resilient IP protocols (BGP, ECMP)
The talk finishes up discussing the pros and cons of the different architectures available:
Monolithic systems which are non-blocking, but have a wide failure domain
Monolithic – expansion toward spine and leaf with SDN for non-blocking switching
Leaf & spine with air-gapped Red and Blue networks
Leaf & spine hybrid with Purple switches connected to both Red and Blue spines to support single homed devices
Leaf & spine Purple. Here, red and blue flows are connected to physically separate switches, but the switches are not identified as red and blue anymore. This is a converged network and an SDN controller is required to provide diverse paths flows to go to two different spines.
For many building a good network for a 2110 or other media-over-IP standards is new and a bit scary. But if there’s one person who knows how to do it, it’s Arista’s Gerard Phillips who’s here to go through the basics and build up the network needed for a large and scalable network.
Scalability is the heart of this, because life does change – your company grows, technology pushes you from SD to HD to UHD etc. So you need to build scalability in from the beginning. Getting this right comes down to choosing the right hardware and having the right architecture.
Gerard looks at switch architecture and bandwidth both in the switch and of the network cables. He then looks towards ‘hub and spoke’ Vs monolithic switch design. What are the pros and cons to each and which is right for you?
SDN – Software Defined Networking – is also a key ingredient in such a network. This is where the routing decisions of the switch infrastructure is taken out of the switches because they have automatic and blinkered algorithms and takes it to a server which has a complete overview of the whole system. For a broadcaster who deals with critical signal chains – this is usually the best approach to give determinism and safety to the network.
PTP – Precision Time Protocol – provides the foundation of the 2110 standard and is therefore very important to studio installations being used to replace black and burst. What are the best ways to distribute this and how can you deal with redundancy?
These topics and more are all covered at this IP Showcase presentation from IBC 2018.
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