Wes Simpson

Video: Monolithic and Spine-Leaf Architectures

Posted on by Russell Trafford-Jones

It’s hard to talk about SMPTE 2110 system design without hearing the term ‘spine and leaf’. It’s a fundamental decision that needs to be made early on in the project; how many switches will you use and how will they be interconnected? Deciding is not without accepting compromises, so what needs to be considered?

Chris Lapp from Diversified shares his experience in designing such systems. Monolithic design has a single switch at the centre of the network with everything connected directly to it. For redundancy, this is normally complemented by a separate, identical switch providing a second network. For networks which are likely to need to scale, monolithic designs can add a hurdle to expansion once they get full. Also, if there are many ‘low bandwidth’ devices, it may not be cost-effective to attach them. For instance, if your central switch has many 40Gbps ports, it’s a waste to use many to connect to 1Gbps devices such as audio endpoints.

The answer to these problems is spine and leaf. Chris explains that this is more resilient to failure and allows easy scaling whilst retaining a non-blocking network. These improvements come at a price, naturally. Firstly, it does cost more and secondly, there is. added complexity. In a large facility with endpoints spread out, spine and leaf may be the only sensible option. However, Chris explores a cheaper version of spine and leaf often called ‘hub and spoke’ or ‘hybrid’.

If you are interested in this topic, listen to last week’s video from Arista’s Gerard Philips which talked in more detail about network design covering the pros and cons of spine and leaf, control using IGMP and SDN, PTP design amongst other topics. Read more here.

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Speakers

Chris Lapp Chris Lapp
Project Engineer, SME Routing
Diversified
Wes Simpson Wes Simpson
President, Telcom Product Consulting
Owner, LearnIPVideo.com

Video: Case Study – ST 2110 4K OB Van for AMV

Posted on by Russell Trafford-Jones

Systems based on SMPTE ST 2110 continue to come online throughout the year and, as they do, it’s worth seeing the choices they made to make it happen. We recently featured a project building two OB truck and how they worked around COVID 19 to deliver them. Today we’re looking at an OB truck based on Grass Valley and Cisco equipment.

Anup Mehta and Rahul Parameswaran from Cisco join the VSF’s Wes Simpson to explain their approach to getting ST 2110 working to deliver a scalable truck for All Mobile Video. This brief was to deliver a truck based on NMOS control, maximal COTS equipment, flexible networking with scalable PTP and security.

Thinking back to yesterday’s talk on Network Architecture we recognise the ‘hub and spoke’ architecture in use which makes a lot of sense in OB trucks. Using monolithic routers is initially tempting for OB trucks, but there is a need for a lot of 1G and 10G ports which tends to use up high-bandwidth ports on core routers quickly. Therefore moving to a monolithic architecture with multiple, directly connected, access switches makes them most sense. As Gerard Philips commented, this is a specialised form of the more general ‘spine-leaf’ architecture which is typically deployed in larger systems.

One argument against using IGMP/PIM routing in larger installations is that those protocols have no understanding of the wider picture. They don’t take a system-wide view like a SDN controller would. If IGMP is a paper roadmap, SDN is satnav with up to date road metrics, full knowledge of width/weight restrictions and live traffic alerts. To address this, Cisco created their own technology Non-Blocking Multicast (NBM) which takes in to account the bandwidth of the streams and works closely with Cisco’s DCNM (Data Centre Network Manager). These Cisco technologies allow more insight into the system as a whole, thus make better decisions.

Anup and Rahul continue to explain how the implementation of PTP was scaled by offloading the processing to line cards than relying on the main CPU of the unit before explaining how the DCNM, not only supporting the NBM feature, also supports GV Orbit. This is the configuration and system management unit from GV. From a security perspective, the network, by default, denies access to any connections into the port plus it has the ability to enforce bandwidth limits to stop accidental flooding or similar.

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Speakers

Anup Mehta Anup Mehta
Product Manager,
Cisco
Rahul Parameswaran Rahul Parameswaran
Senior Technical Product Manager,
Cisco

Video: Hybrid SDI/ST 2110 Workflows

Posted on by Russell Trafford-Jones

It’s no secret that SDI is still the way to go for some new installations. For all the valid interest in SMPTE’s ST 2110, the cost savings are only realised either on a large scale or in the case that a system needs continuous flexibility (such as an OB truck) or scalability in the future. Those installations which have gone IP still have some SDI lying around somewhere. Currently, there are few situations where there is an absolute ‘no SDI’ policy because there are few business cases which can afford it.

Looking at the current deployments of broadcast 2110, we have large, often public, broadcasters who are undergoing a tech refresh for a building and can’t justify such as massive investment in SDI or they are aiming to achieve specific savings such as Discovery’s Eurosport Transformation Project which is an inspirational, international project to do remote production for whole buildings. We also have OB trucks who benefit significantly from reduced cabling, higher density routing and flexibility. For a more detailed view on 2110 in trucks, watch this video from NEP. In these scenarios, there is nearly always SDI still involved. Some equipment doesn’t yet work fully in 2110, some doesn’t yet work at all and while there are IP versions of some products, the freelance community still needs to learn how to use the new products or work in the new workflows. If you have a big enough project, you’ll hit the ‘vendor not yet ready’ problem, if you have an OB-truck or similar, you are likely to have to deal with the freelance experience issue. Both are reducing, but are still real and need to be dealt with.

Kevin Salvidge from Leader joins the VSF’s Wes Simpson to share his experience of these SDI/IP mixed workflows, many of which are in OB trucks so also include mixed HDR workflows. He starts by talking about PTP and GPS discussing how timing needs to be synced between locations. He then takes a closer look at the job of the camera shaders who make sure all the cameras have the same colour, exposure etc. Kevin talks about how live production in HDR and SDR work touching on the problem of ‘immediacy’. Shaders need to swap between cameras quickly and are used to the immediate switch that SDI can provide. IP can’t offer quite the same immediacy, Kevin says that some providers have added delays into the SDI switches to match the IP switch times within the same truck. This helps set expectations and stop operators pressing two or more times to get a switch made.

Kevin finishes his talk on the topic of synchronising analogue timing signals with PTP. Kevin shows us the different tools you can use to monitor these signals such as a display of PTP timing against B&B timing, a BMCA data readout of data from the PTP grandmasters to check if the BMCA algorithm is working correctly, PTP delay time, packet inter-arrival time, path delay, traffic shaping monitoring. He then closes with a Q&A talking about the continued prevalence of SDI, what ‘eye patterns’ are in the IP world and increasing HDR roll-outs.

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Speaker

Kevin Slavidge
European Regional Development Manager
Leader Europe Ltd.
Wes Simpson Moderator: Wes Simpson
President, Telcom Product Consulting
Owner, LearnIPVideo.com

Video: RIST: What is the Future?

Posted on by Russell Trafford-Jones

Many see RIST as a new kid on the block, but they’ve worked quickly since their formation 3 years ago, having produced two specifications and now working on the third. RIST makes sending video over the internet reliable as it corrects for missing data. The protocol which, aims at multi-vendor interoperability, continues to gather interest with the RIST Forum now having over 80 companies.

“What does RIST do today” and “what’s next?” are the two questions Rick Ackermans, Chair of the RIST activity group at the VSF, is here to answer. Firstly, then, Rick looks at the documents already published, TR-06-1 and TR-06-2. Also known as the simple profile TR-06-01 has already received an update to allow for continuous measurement of the round trip time (RTT) of the link. Rick makes it clear that these are living specifications and the VSF won’t shy away from updating them when it helps keep the protocol relevant and responsive to the industry. TR-06-2 is the main profile which was released last year.

The simple and main profiles are summarised in this article and by Rick in the video. The simple profile provides a sender or receiver which can speak plain RTP and also run with high-performance packet recovery and seamless switching.

Main Profile brings in encryption and a powerful tool, GRE. As we wrote about last week, the idea of a tunnel is to hide complexity from the network infrastructure. Tunnelling allows for bidirectional data flow under one connection which is transparent to the network carrying the tunnel and to the endpoints. This enables a lot of flexibility. Not only does it allow for the connection to be set up in either direction, to suit whichever is easiest for firewall reasons, but it also allows generic data to be sent meaning you could send PTZ camera control data along with the video and audio.

But the highlight of this presentation is looking to the future and hearing about the advanced profile which is still in progress. Planned, though not promised, are features such as auto-configuration where a receiver works out many of the parameters of the link itself and dynamic reconfiguration where the sender and receiver respond to changing conditions of the link/network. Also in the works is a hybrid operation mode for satellites allowing and an internet connection to be used in addition to the satellite feed to receive and deliver re-requests.

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Speakers

Rick Ackermans Rick Ackermans
Rist Activity Group Chair
Director of RF & Transmissions Engineering, CBS
Wes Simpson Wes Simpson
Co-Chair, RIST Activity Group,
Owner, LearnIPVideo.com