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Page 1 of 25 © Polycom University Slide 1 - Slide 1 Slide notes Page 2 of 25 © Polycom University Slide 2 - Introduction Slide notes Welcome to this module introducing a technology overview and an introduction to the technical language often used when discussing video and audio collaboration. In this module we will cover what infrastructure is, what networks are and how they are created, and what this all means specifically when discussed in a video and audio collaboration environment. We will also cover some video technology basics to help make sense of what high definition video actually means and how it is measured. Page 3 of 25 © Polycom University Slide 3 - Infrastructure Basics Slide notes Let’s get started. Infrastructure is the hardware and its associated software components that make computers and other devices such as the elements of a video and audio collaboration solution operate seamlessly together. But what does that mean? Well, when we talk about hardware, what we mean is the physical devices which take information and process it in some way. Software is what tells the hardware what to do and how exactly to process that information - think about the computer you're using right now; the computer itself is the hardware (the brain power, if you like), but it doesn't know what to do unless you are using software such as an operating system like Windows, as well as a program which understands how to play this course for you. Page 4 of 25 © Polycom University Slide 4 - Networking Basics Slide notes So infrastructure can't achieve much without a network, but at the same time, a network wouldn't be a network without infrastructure. A network just means connections between two or more computers or other devices that allows them to communicate and share resources with each other. Many people have simple networks at home, which allows them to share printers, internet connections, programs, and files, for example. If devices are part of the same network, they can send and receive information through something called a switch. A switch is a hardware device that joins multiple computers together within one part of the network - when you see a network cable disappear into a wall in your office, it ends up plugged into a switch somewhere in the company computer room. No additional infrastructure is required to create what we call a local network, one where connections are made within an environment like an office or home. This type of environment is referred to as a Local Area Network, or LAN. Page 5 of 25 © Polycom University Slide 5 - Networking Basics Slide notes If two computers are on the same network, how does one know when the other is asking it for some information or has a request of some kind? Well, each device on the LAN requires an address before it can join the network, and this is how the devices can find each other. You may have heard the term IP or IP address, and we're going to take a quick look at what that means now. The word internet is just a shortened version of 'interconnected network' and refers to multiple networks all connected and accessible from each other. This is what the I in IP stands for. The P in IP stands for protocol. A protocol is a standard set of rules that defines the way information should be sent. This ensures that if, say, an email is sent, the receiving computer understands that it is an email and therefore knows how to make it accessible to the end-user. There are many protocols for many different types of communication. An Internet Protocol (IP) address is a numerical label assigned to every device on a computer network, and is required to send and receive information. Just like a mailing address, the IP address ensures that information is sent to and received by the desired location. A public IP address is just an IP address accessible to anyone with access to the internet. Page 6 of 25 © Polycom University Slide 6 - Networking Basics Slide notes The IP address can be configured for each network device, and can be changed at any time. IP addresses related to a single location or enterprise use a subnet which identify the IP addresses as part of the same network. A subnet is a method of organizing the many millions of possible IP addresses into small groups. When all network devices understand which subnet they are using, it allows them to understand what is ‘inside’ their network, and what is ‘outside’ their network. In addition to IP addresses, each network device is also assigned a Media Access Control, or MAC address. This permanent, unique address is assigned in manufacturing, and is typically never changed. Page 7 of 25 © Polycom University Slide 7 - Networking Basics Slide notes There are two more important concepts which relate to IP addresses that we'll cover quickly. The first is DHCP. DHCP stands for Dynamic Host Configuration Protocol. A DHCP server automatically assigns an IP address from a ‘pool’ of available IP addresses to each device. Most IP devices support DHCP to simplify network connectivity, and Polycom products are no exception. All the desktop and room systems are set to DHCP, so that all you need to provide is power and a network cable plugged into a switch to get started. Page 8 of 25 © Polycom University Slide 8 - Networking Basics Slide notes The second is DNS, which stands for Domain Name Service. DNS is what makes it possible to navigate to www.polycom.com (known as a domain name) using a web browser, instead of having to remember the IP address. When we talk about a domain in terms of computing, what we mean is a single network, essentially. A domain name is just a name through which a network is accessible. So really, DNS is like a big list of domain names and their IP addresses. Page 9 of 25 © Polycom University Slide 9 - Networking Basics Slide notes So what happens when you (fairly inevitably) want to connect to a network outside the one you're part of? If a computer wants to send information to a computer that is not connected to the same switch, the information is automatically sent to the default gateway, which is an IP address configured into the router. Routers are devices that join multiple wired or wireless networks together by talking to switches. The router uses the address information received from the source device to locate the destination; if it recognizes the IP address as being one part of the local network, it will send the information back into the LAN - this could occur if the destination device is on the same network but on a different switch, for example. If it doesn't recognize the IP address, it will sent it out to the internet. Page 10 of 25 © Polycom University Slide 10 - Networking Basics Slide notes In between the router and the internet is often a device called a firewall. This is a security device which protects the network by blocking all data entering the LAN with the exception of what has specifically been allowed. One way firewalls assess data is through the port number, which identifies which type of information is flowing through the network. Ports are like doorways or entry gates for specific types of information. For example, all internet browser data arrives at Port 80, and email at Port 25. The firewall is like the bouncer that determines who is allowed in. It can be configured with different rules for different ports. Page 11 of 25 © Polycom University Slide 11 - Networking Basics Slide notes Here's a simple diagram showing an email leaving an email server and heading to another. It goes from the server to their local switch. The switch sends it to the router. The router looks at it and doesn't know the address, so it sends it to the internet via the firewall. This then negotiates the Internet, and arrives at the firewall at the edge of the recipient's network, through their router, which looks up the address and recognizes it, sends it to the local switch, and the second server receives the email. Page 12 of 25 © Polycom University Slide 12 - Video Collaboration Basics Slide notes So that's what networks are and how they work together. Putting this information into a video and audio collaboration perspective, what do we mean by infrastructure? Well, infrastructure is what manages endpoints, content, bandwidth, and access. As these terms are heard a lot, we'll just cover quickly what they all mean. - Endpoints are the ways individuals and groups send and receive information. They include conference and desktop phones, software such as RealPresence Desktop or Microsoft Lync, and video collaboration systems like an HDX or RealPresence Group 500. - Content is the information that is displayed and communicated from one endpoint to another. This may be documents, data or video, though there are others as well. - Bandwidth is a measure of capacity. It is an especially important concept when transferring video images because video requires a lot of hardware and network resources. The term “bandwidth” is used to refer to the amount of capacity available and the amount of capacity required. - Access is how entry into a system is controlled. It includes security measures to ensure that uninvited users cannot gain entry to the network. Security measures also ensure that information is not available outside the network without authorization. When we use the term infrastructure for a network used for video and audio collaboration, generally what we mean is not an endpoint but something that does something to enhance the capabilities of the video and audio collaboration network. You can also specify the kind of infrastructure you mean, for example, network infrastructure would refer to switches, routers and firewalls. Page 13 of 25 © Polycom University Slide 13 - Video Collaboration Basics Slide notes When we're talking about using a network for video and audio collaboration, how do the devices we've discussed so far fit into that picture? This diagram shows a simple internal network that connects two devices, in this case they are video endpoints. Networks are often represented as clouds in diagrams when the actual network components are not relevant; the purpose of the diagram is to show the devices in a simple way and the network infrastructure will take care of everything behind the scenes without any need for further detail. You would use a simple network like this is you wanted to enable simple video or voice calls between two devices on an internal network. We call this communication between two devices a point to point call. Page 14 of 25 © Polycom University Slide 14 - Video Collaboration Basics Slide notes A call like this with more than two participants is called a multipoint call. Polycom offers software called a “software key” that can be added to conferencing devices to ‘unlock’ functionality, and one of the keys which can be added to an endpoint is enabling multipoint calls. All endpoints dial into the endpoint with the software key and can communicate with each other. Page 15 of 25 © Polycom University Slide 15 - Video Collaboration Basics Slide notes If you want to enable multiple, simultaneous multi-point calls in a larger network, you need a Multipoint Control Unit. Most people refer to this as an MCU or bridge (this is just a shortened form of conference bridge). A bridge is an infrastructure device that can manage many different calls and connect all endpoints to their intended meeting. Bridges come in different sizes and capacities, and the capacity of the bridge determines how many different endpoints can connect. Page 16 of 25 © Polycom University Slide 16 - Video Collaboration Basics Slide notes Another definition for a commonly found piece of the video collaboration puzzle – the gatekeeper. The gatekeeper is a device which has two main jobs. Firstly, it enables callers to dial a simple extension number rather than having to know an IP address. Secondly, it enables something called Call Admission Control. This polices the number of calls going onto the network to make sure the bandwidth required does not exceed the bandwidth available. Page 17 of 25 © Polycom University Slide 17 - Video Collaboration Basics Slide notes Let’s expand our video network to consider communication outside the LAN. Calls made within a network are called “on-net” calls. Most organizations also require the ability to make “off-net” calls, which are calls made from one network to another. Off-net calls are often connected through the internet. This capability to make off-net calls often requires additional infrastructure due to the firewalls we talked about earlier. Video and audio information is tricky for firewalls to understand and often even a configured firewall will make the odd mistake and block information by accident leading to loss of video or audio. To make this more robust, it is common to implement what we call a firewall traversal solution. Traversal just means to travel through something, and sure enough, firewall traversal allows audio and video to travel through the firewall so it can be sent to the endpoint at the far end. Page 18 of 25 © Polycom University Slide 18 - Video Collaboration Basics Slide notes We'll take a look now at technology designed to help endpoints work better over networks. For a moment, just think of how much you have running on your computer right now, between email, internet, antivirus, documents stored and saved on the network, printing, and so on. If you work in an office with more than one site, then the chances are that you are working on a Wide Area Network, or WAN, where each site is linked. This is relevant as the links between these sites have costs associated with them, and often they are designed to minimize these costs as much as possible by only paying for the capacity (bandwidth) that is required. Video is very much a real-time application, by which we mean that you need to see and hear the far end and have it seem realistic with as little delay as possible. This is tough on the network as it takes a lot of bandwidth, and often a lot of the available bandwidth on a network is taken up by all the information already flying around. So apart from adding more bandwidth, how else can we try and minimize bandwidth without sacrificing call quality? Page 19 of 25 © Polycom University Slide 19 - Video Collaboration Basics Slide notes There are two things we can really do to help with bandwidth usage. The first is to reduce the bandwidth requirements, and the second is to help the endpoints and MCU be as resilient as possible with regards to how they deal with bandwidth issues. We're going to look at reducing bandwidth requirements first, and to do this we're going to look a little bit deeper into endpoints and how they work. But just a bit deeper, don't worry! You may have heard an endpoint being referred to as a 'codec'. This might sound like a strange word, but all it means is that the endpoint codes the signal from the camera and microphone to send to the far end, and decodes the signal from the far end so you can see and hear it. Codec is just a shortened version of 'coder-decoder'. This coding and decoding process involves protocols like we were discussing earlier, and one of the things the protocol does is use a process called compression, which basically does what it says - it compresses the data so it takes up less bandwidth and therefore less bandwidth is needed to make a call. For example, H.264 is a protocol used by the codec to achieve HD video, and part of what it does is provide some compression. But H.264 High Profile is a more efficient protocol which is able to compress the data even further, saving up to 50% on the bandwidth requirements needed for H.264. Page 20 of 25 © Polycom University Slide 20 - Video Collaboration Basics Slide notes So the second thing we can do is to help the endpoints and MCU be as resilient as possible with regards to how they deal with bandwidth issues. To do this, Polycom adds software called Lost Packet Recovery, or LPR, to endpoints and MCUs. Information sent through a network is split into tiny pieces called packets, and some of these packets can become lost or delayed. With video and the requirement for real-time service, lost and delayed packets can cause unwanted behavior such as freezing audio and video, odd things happening to the video like blocks of it appearing larger than they should, or video and audio dropping out completely. Without going into the technical side of it, LPR performs a function known as error correction, and this helps rebuild the video and audio as best possible while keeping the picture and audio quality as good as it can be. This means that you could have up to 5% packet loss on your video call and you wouldn't be able to tell anything was wrong. 5% might not sound like a lot, but it is actually enough to make the call freeze severely and maybe even disconnect, so it's a really good thing! When we talk about LPR for the audio side, you will hear it described as Siren LPR. This is because Polycom's wideband audio is referred to as Siren technology. So LPR will work for video and audio, providing the best possible experience for your network conditions. This doesn't mean that you don't need more bandwidth, but it will do the best it can to help. Page 21 of 25 © Polycom University Slide 21 - Video Technology Basics Slide notes The last thing we're going to take a look at here is a little bit about video technology. This may seem a little strange, but understanding what high definition video is and how it is described will help when looking at many aspects of video collaboration, including endpoint and infrastructure capability. Let's start by explaining two often used terms - frame rate and resolution. A moving picture such as that required by a videoconferencing endpoint is created by sending tiny blocks of video called pixels which build the picture in rows. A frame is when this whole picture has built once. So frame rate is the number of times per second the whole picture is sent by the endpoint, measured in frames per second (fps). The higher the frame rate, the smoother the resulting moving image and the less likely the human eye can detect the picture building. If you have seen a call with a low frame rate, you may well have noticed little jumps and maybe some screen flicker as the picture doesn't build quickly enough for it to disguise this process. To give you a reference, the most commonly used frame rate at this time is 30fps. It's pretty quick! Page 22 of 25 © Polycom University Slide 22 - Video Technology Basics Slide notes Resolution is measure of how many pixels fit into the screen. The fewer the pixels, the lower the resolution. The higher the number, the higher the resolution. Resolution makes a tremendous difference to the picture quality, as the higher the resolution, the smaller the pixel size, and the clearer the image appears. Common Intermediate Format, or CIF, is the format of an inexpensive webcam. CIF resolution is 352 by 288, meaning the full screen display is 352 pixels wide and 288 lines of pixels high. Standard Definition, also known as SD or 4CIF, has about 4 times the resolution of CIF, or about 720 by 480. High Definition, or HD, is the highest quality video image, and is typically at least 1280 by 720 pixels. A resolution of 1280 by 720 is often just referred to as just 720, and a resolution of 1920 by 1080 as just 1080. So when someone mentions an endpoint in a call at 1080 60fps, you know that it's a high resolution call with a high frame rate - this will require more bandwidth than a lower quality call, but it will provide a very high quality picture which moves smoothly and is very lifelike. Page 23 of 25 © Polycom University Slide 23 - Video Technology Basics Slide notes Finally, when discussing video specifically, you may have heard the resolution being referred to with a letter after it as well. We're just going to quickly explain what that means so that it is absolutely clear how this all fits together. When a screen builds a picture, it uses a process called scanning. In the same way an endpoint sends a frame which is built on the screen, scanning is how the screen actually builds that frame. You can't usually see this happening, and in fact the screen builds the whole picture around fifty times per second, usually. There are two types of scanning, and the first we will look at is called progressive scanning. If you see something discussing screen quality and it says 1080p, the 'p' means it uses progressive scanning. Progressive scanning is when the picture starts to build at the top left, scans the top line then jumps to the start of the second line, builds the second line, and so on until all lines are complete, and then it jumps back to the top left and starts over. Progressive scanning gives the better result of the two methods, but requires a fair bit of processing power within the screen as it's working pretty hard. Page 24 of 25 © Polycom University Slide 24 - Video Technology Basics Slide notes The second type of scanning is called interlaced scanning. If you see something discussing screen quality and it says 1080i, the 'i' means it uses interlaced scanning. Interlaced scanning is when the picture starts to build at the top left, but it starts building in two places, once for the odd numbered lines, and ones for the even numbered lines. So the odd number scans the top line then jumps to the start of the third line, builds the third line, and so on until all odd lines are complete, and then it jumps back to the top left and starts over. The even number scans the second line, then jumps to the start of the fourth line, and so on. Interlaced scanning doesn't need as much processing power within the screen, but it is easier to see flickering as the screen builds the picture, especially if you are sitting off to the side slightly and aren't looking straight onto the screen. Page 25 of 25 © Polycom University Slide 25 Slide notes This material, including the script, may be downloaded from the course page. When you're ready, click the button to exit the course ame rate, the smoother the resulting moving image and the less likely the human eye can detect the picture building. If you have seen a call with a low frame rate, you may well have noticed little jumps and maybe some screen flicker as the picture doesn't build quickly enough for it to disguise this process. To give you a reference, the most commonly used frame rate at this time is 30fps. It's pretty quick! Page 22 of 25 © Polycom University Slide 22 - Video Technology Basics Slide notes Resolution is measure of how many pixels fit into the screen. The fewer the pixels, the lower the resolution. The higher the number, the higher the resolution. Resolution makes a tremendous difference to the picture quality, as the higher the resolution, the smaller the pixel size, and the clearer the image appears. Common Intermediate Format, or CIF, is the format of an inexpensive webcam. CIF resolution is 352 by 288, meaning the full screen display is 352 pixels wide and 288 lines of pixels high. Standard Definition, also known as SD or 4CIF, has about 4 times the resolution of CIF, or about 720 by 480. High Definition, or HD, is the highest quality video image, and is typically at least 1280 by 720 pixels. A resolution of 1280 by 720 is often just referred to as just 720, and a resolution of 1920 by 1080 as just 1080. So when someone mentions an endpoint in a call at 1080 60fps, you know that it's a high resolution call with a high frame rate - this will require more bandwidth than a lower quality call, but it will provide a very high quality picture which moves smoothly and is very lifelike. Page 23 of 25 © Polycom University Slide 23 - Video Technology Basics Slide notes Finally, when discussing video specifically, you may have heard the resolution being referred to with a letter after it as well. We're just going to quickly explain what that means so that it is absolutely clear how this all fits together. When a screen builds a picture, it u