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Technology: Designing, Installing and Managing Home Area Networks (3/3/2011)
By Darren Kirby, Bespoke Technology
Bill Gates once made a statement that "One day every home will have a PC". This now can be said of the HAN (Home Area Network). A report by ABI research states that by 2012 460 million network-enabled devices will be shipped globally, and whilst the majority of users will be able to simply connect these to their unmanaged routers, as consumers get a greater appetite for increased services and functionally, the network must also become more intelligent to enable users to achieve their goals. This means that greater networking skills are needed by installers.
Over the last few years the HAN has developed from more that just a single wire from your broadband router to your desktop PC. The majority of homes now have wireless networks as standard, and new homes are having CAT5 installed as part of the build. Online gaming, streaming music and films, smart meters etc, now mean that it is essential to have a reliable HAN in place to provide the end user with the right experience and reliable communication.
Storage and backups are now part of the HAN - terabytes of storage are required to store pictures, music and video, and these must be protected in the event of a hardware failure, with mirrored disk drives and backups being run overnight to spare disks. The HAN must provide a reliable, always-available service with enough bandwidth and intelligence to cope with the amount of data currently used, and be scalable for the future.
As AV and IT services converge and applications are increasingly moving toward IP-based technologies, more and more data over the single CAT5/fibre cable inevitably requires intelligent devices to drive these efficiently and reliably. The time of plugging a cheap unmanaged router and waiting for all the lights to flash green is rapidly coming to an end - unless of course you want to run into issues that can't be diagnosed and fixed!
The network should follow a specific design, with cable installed by professionals who understand such things as the maximum bend radius of CAT5 cable, the maximum lengths that can be used, and who can produce cable wiring diagrams with test results for each cable run. The hardware should be specified to cope with the data throughput. The IP address range should be designed to have enough capacity so that the whole network doesn't need to be re-addressed if the client decides to expand the system.
The network should be logically segmented through the use of VLANs keeping delay-sensitive traffic, such as voice, separate from the normal data traffic, so preventing the latest movie download from interfering with phone conversations. Above all, the network, no matter how small, should be documented. Diagrams and documentation on IP addressing and locations of devices should be kept on site, otherwise it can double the length of time to diagnose a problem if the engineer first has to figure out how the network is connected and configured.
Understanding IP theory
Installers need to understand IP network theory if they are to specify the correct hardware and provide a redundant and scalable design. They also need sufficient knowledge to be able to troubleshoot problems.
One of the most important parts of the network is IP addressing. If the network is segmented through the use of VLANs in order to separate services from one another, installers should have enough knowledge to subnet the addressing scheme to provide multiple networks, one for each VLAN. Once networks are segmented using VLANs, you need to understand how communication is configured between the VLANs using routing.
The OSI model
To understand the different layers and protocols of communication between IP devices, installers should learn and understand the OSI model and TCP/IP model. Each layer of the OSI model is a collection of functions that provides services to the layers above, and receives services from the layers below. The TCP/IP model also uses the layered approach, defining the protocols in each layer. So understanding both of these models will help with troubleshooting when a specific communication is failing.
Types of home network
There are three types of home network:
Wired - always the preferred method where possible, mainly using copper CAT5e/CAT6 cables . Cable runs are brought back to a central location and terminated on a patch panel which is then connected to a layer 2 switch to form the hub of the network. Where cable runs exceed 100 meters, fibre optic cable is used. This is generally only used to link copper cable runs i.e. between floors and buildings.
Wireless - ideal for retrofit situations where there is no chance of cables being run. Prior to specifying the number of access points (APs) required, it is always advisable to carry out a wireless survey. Fluke Networks have a survey tool and there are many open source tools available. If the installation requires multiple APs it is always advisable to connect them to a wireless controller for management and redundancy. Wireless can be unreliable, and its environment can affect its performance, for example, a location with a lot of solid reflective surfaces can cause issues with range and connectivity.
Ethernet over Power (EoP) - or homeplugs as they are more commonly known, are good for instances where physical cables are not an option and wireless signals suffer from interference. They connect into a standard power socket (all sockets being used must be on the same electrical phase) and through their detection mechanisms detect other homeplugs to create a secure network. The current standard is HomePlug AV which supports 200Mb/s, with the protocol overhead actual throughput being around 150Mb/s. The only downside to these devices is that they are not as intelligent as switches and don't currently maintain any forwarding tables to intelligently switch traffic to its destination. The traffic is simply broadcast out on to the network which can cause throughput issues if collisions and retransmissions occur.
The issues to consider when designing a HAN are as follows:
* What services are going to be running over the network, e.g. AV, voice etc?
Hardware and software
In general, the cabling used would be CAT5e or CAT6 from a central equipment room or centrally-located patch panel out to the locations which require network connectivity. In larger installations, there may be two locations where cable runs are brought back to, and these two locations would be linked with multimode fibre. Cables can be bundled together, typically with 2 x CAT5e, speaker cable, coaxial and control cable, thus eliminating the need to run multiple single cable runs.
The network can be wired or wireless, and in many instances, there is a combination of the two. It is always preferable to connect the wireless AP in each location to a wired point to connect back to the switch or wireless controller.
If the network is large enough too use fibre, then the switch should have interfaces which can accommodate both fibre and copper. If there are switches connected together for a higher port density or to link floors, these ports should be of a higher capacity i.e. Gigabit, in order to avoid bottlenecks when aggregating multiple 100Mb/s ports. A managed switch is always preferable, as this allows the installer to have control over the configuration, for segmenting the network through the use of VLANs, configuration of IP addressing and routing, and checking and fixing port speeds. Logs on the device to aid troubleshooting if necessary, are also important.
Installation and commissioning
All network kit should be setup, configured and tested off site prior to the network being installed. With the network being the backbone for communication and distribution of traditional AV services, its hardware should be the first piece of infrastructure to be installed. The network devices should then be connected, for example, the switch, router, wireless access points, control systems, HD distribution etc. Finally, the patching between floors via patch panels should be connected.
Commissioning should be a fairly straightforward process. The test plan should be re-run and compared with the offsite results. This can then be handed over and signed off.
Ongoing maintenance issues
Provided the network has been designed correctly for the environment, set up as per the design and tested, other than hardware failures which can occasionally occur, the network should be operate in the background, and be invisible to the user.
Unlike PCs, network firmware and software is not generally updated unless an operational bug has occurred or a new feature is required. If the client has a service contract, then remote monitoring can be setup to alert when there are connection issues or the health of the hardware has degraded.
The most common of network issues are internet connection failure, which is mostly provider-related, but can sometimes be due to the device itself requiring a reboot. Other problems can result from laptops not being able to obtain a DHCP address because the original DHCP lease was set to infinite, meaning that each time a temporary device connects to the network, it is given an address. The address is never given back to the pool when the device disconnects because of the lease period, and over time as devices connect and disconnect, the pool runs out of addresses.
As a general rule, an infrastructure device i.e. one which runs the system and must be on the network at all times, should be given a fixed IP address to avoid any DHCP issues. IP address ranges should have 50% of addresses free from day one, in order to allow for future expansion.
If the installer understands how to specify the correct products for the network, network design fundamentals and protocols, IP and configuration, the client will get a reliable, fast, scalable network which is 99.99% reliable, able to scale, and handle new services. The alternative too often results in the installer being called because touchpanels are unresponsive, or the iTunes library is offline, or when streaming movies from the Kaleidescape, the picture is breaking up or jittery.
The majority of products and manufactures are looking toward IP as the standard communication mechanism. The network is becoming the core of the infrastructure for the CI industry no matter how big or small the installation. Demand for skilled network services is growing and will increase as manufacturers release more and more products with Ethernet/IP capability.
If you are new to networking, look at the For Dummies range of books, and in particular the Networking All-in-One for Dummies (4th Edition) and TCP/IP for Dummies (6th Edition). These break down the acronyms and jargon into a language which is easy to understand to provide a basic knowledge. CEDIA also runs two IP courses, namely Networking Theory and Practice, and Advanced IP Network, and I would strongly recommend attending the five-day Cisco CCENT (Cisco Certified Entry Networking Technician) course that covers all of the basic fundamentals needed.
Darren Kirby is a Director of Bespoke Technology, provider of high-end control and AV solutions, and the design and installation of data and voice networks for the CI industry.
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