Networking

Video: Fibre Optics in the LAN and Data Centre

Posted on by Russell Trafford-Jones

Fibres are the lifeblood of the major infrastructure broadcasters have today. But do you remember your SC from your LC connectors? Do you know which cable types are allowed in permenant installations? Did you know you can damage connectors by mating the wrong fibre endings? For some buildings, there’s only one fibre and connector type making patch cable selection all the easier. However there are always exceptions and when it comes to ordering more, do you know what to look out for to get exactly the right ones?

This video from Lowell Vanderpool takes a swift, but comprehensive, look at fibre types, connector types, light budget, ferrule types and SFPs. Delving straight in, Lowell quickly establishes the key differences between single-mode and multi-mode fibre with the latter using wider-diameter fibres. This keeps the costs down, but compared to single-mode fibre can’t transmit as far. Due to their cost, multi-mode fibres are common within the datacentre so Lowell takes us through the multimode cable types from the legacy OM1 to the latest OM5 cable.

OM1 cable was rated for 1GB, but the currently used OM3 and 4 fibre types can carry 10Gb up to 550m. Multimode fibres are typically colour-coded with OM3 an 4 being ‘aqua’. OM5 is the latest cable to standardised which can support Short Wavelength Division Multiplexing (SWDM) whereby 4 frequencies are sent down the same fibre giving an overall bandwidth of 10Gbx4 = 40GbE. For longer-distance, the yellow OS1 and, more recently, OS2 fibre types will achieve up to 10km distance.

Lowell explains that whilst 10km is far enough for many inter-building links, the distance quoted is a maximum which excludes the losses incurred as light leaves one fibre and enters another at connection points. Lowell has an excellent graphic which shows the overall light ‘budget’, how each connector represents a major drop in signal and how each interface will also reflect small amounts of the signal back up the fibre.

Having dealt with the inside of the cables, Lowell brings up the important topic of the outer jacket. All cables have different options for the outer jacket (for electrical cables, usually called insulation). These outer jackets allow for varying amounts of flexibility, water-tightness and armouring. Sometimes forgotten is that they have also got different properties in the event of fire. Depending on where a cable is, there are different rules on how flame retardant the cable can be. For instance, in the plenum of a room (false ceiling/wall) and a riser there are different requirements than patching between racks. Some areas keeping smoke low is important, in others ensuring fire doesn’t travel between areas is the aim so Lowell cautions us to check the local regulations.

The final part of the video covers connectors, ferrules and SFPs. Connectors come in many types, although as Lowell points out, LC is most popular in server rooms. LC connectors can come in pairs, locked together and called ‘duplex’ or individually, known as ‘simplex’. Lowell looks at pretty much every type of connector you might encounter from the legacy, metal bayonet & screw connectors (FC, ST) to the low-insertion loss, capped EC2000 connector for single mode cables and popular for telco applications. Lowell gives a close look at MPT and MPO connectors which combine 1×12 or 2×12 fibres into one connector making for a very high capacity connection. We also see how the fibres can be broken out individually at the other end into a breakout cassette.

The white, protruding end to a connector is called the ferrule and contains the fibre in the centre. The solid surround is shaped and polished to minimise gaps between the two fibre ends and to fully align the fibre ends themselves. Any errors will lead to loss of light due to it spilling out of the fibre or to excessive light bouncing back down the cable. Lowell highlights the existence of angled ferrules which will cause damage if mated with flat connectors.

The video finishes with a detailed talk through the make up of an SFP (Small Form-factor Pluggable) transceiver looking and what is going on inside. We see how the incoming data needs to be serialised, how heat dissipation and optical lanes are handled plus how that affects the cost.

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Speaker

Lowell Vanderpool Lowell Vanderpool
Technical Trainger,
Lowell Vanderpool YouTube Channel

Video: IP Media Networks for Live Production

Posted on by Russell Trafford-Jones

Building and controlling a network for SMPTE ST 2110 go hand in hand when it comes to planning an installation. As ST 2110 delivers all media essences separately, networks can easily end up carrying tens of thousands of flows emphasising the need for efficient network design and having a full understanding of the paths your media are using.

This video is co-presented by Nevion and Arista and starts by observing that the traditional difference between a LAN and WAN is being eroded leading as WANs get faster and better, we find that we can now deliver multi-location broadcast facilities which act similarly to if everything was co-located. Moreover, introduces Martin Walbum Media Function virtualisation which is enabled by network-connected equipment allowing for shared processing and shared control. For instance, it’s now possible to house all equipment in a datacentre and allow this to be used remotely maximising the utilisation of the equipment allowing a broadcaster to maximise the value of its purchases and minimise costs.

Arista’s Gerard Phillips takes a look at SDI systems to understand how we expect IP systems to behave and what we expect them to do. The system needs to deliver high throughput, instantaneous switching with low latency and no tolerance for failure. In order to do this, not only do we need to get the right software but to deliver the resilience we need, the network needs the correct architecture. Gerard takes us through the different options starting with a typical, flat, layer 2 networks and working up to leaf and spine along with a treatment of red, blue and purple networks.

Gerard recently did a deep dive on network design for live production for the IET. Take a look for much more detail on how to architect a network for uncompressed media.

Martin then looks at the need for orchestration. Broadcasters expect to deliver systems with, preferably, no downtime. As such, we’ve seen that network elements are typically duplicated as is the traffic which is delivered over two paths and SMPTE ST 2022-7. If you want to take something out of use for planned maintenance, it’s best to do that in a planned, ordered, way meaning you migrate flows away from it until it’s no longer in-circuit. Software-Defined Networks (SDNs), do exactly that. Martin walks us through the pros and cons of managing your network with IGMP and SDN. Gerard’s previous talk also looks at this in detail.

The video finishes with a look at which Arista switches can be used for media and a look at how Arista and Nevion implemented an ST 2110 network at Swiss broadcaster, tpc. This case study is presented in longer form in this video from the IP Showcase.

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Free registration.
Speakers

Gerard Phillips Gerard Phillips
Systems Engineer,
Arista
Martin Walbum Martin Walbum
Senior Vice President of Solution Strategy,
Nevion

Video: HTTP over QUIC is the next generation

Posted on by Russell Trafford-Jones

There’s a lot to like about HTTP/3 from encryption as standard, faster set-up time, better compression and promises better throughput by removing head-of-line blocking. A new protocol making its way through the IETF and based on QUIC, this could have a real impact on anyone involved in streaming.

wolfSSL’s Daniel Stenberg and cURL maintainer, talks to us about HTTP/3 but starts at the beginning with HTTP 1 and 1/1. He outlines some of the issues we had in 1997 such as head-of-line blocking and ephemeral TCP connections. Zooming forward to 2005, HTTP/2 comes on the scene with a single HTTP connection, thus removing the significant overhead of ephemeral TCP connections. HTTP/2 went with a ‘streamed’ connection and could have multiple such streams but one thing that wasn’t solved was head-of-line blocking.

Before moving beyond HTTP/2, Daniel describes the problems that have set in due to ‘ossification’, that is to say, that the routers that time forgot which are still on very old, and often buggy TCP implementations. Innovating is very difficult if replacing the TCP within even a subset of boxes would mean I wasn’t able to send my website globally.

Addressing this ‘ossification’ issue, QUIC has stepped in. Developed on UDP instead of TCP QUIC solves a number of problems. First off, moving from TCP to UDP allows the protocol to live in userspace making it easier to update. Working on UDP instead of TCP means that the protocol regains control of the retransmissions allowing for something more efficient than TCP’s strict acknowledgement rules.

So QUIC becomes the transport layer of HTTP/3. Freeing ourselves from TCP, Daniel explains, allows us to remove the TCP head-of-line blocking problem. HTTP/3 on QUIC brings with it faster handshakes and a connection ID. This connection ID allows you to change IP addresses and still maintain your connection which is a significant improvement on what has gone before. Daniel continues by explaining more benefits of QUICK and HTTP/3 such as its encryption and the ability to have multiple streams.

Daniel finishes up outlining eight challenges for HTTP/3. These include the fact that up to 7% of QUICK attempts fail, dealing with ‘fall back’ algorithms, UDP having seen historically low usage and are less optimised as well as the downsides of userland protocol stacks being that it’s harder to get a standard.

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Download the presentation
Speakers

Daniel Stenberg Daniel Stenberg
curl master, wolfSSL
main author,

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