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IP Networking TI 310 Ethernet networking (1.1 EN) General information TI 310 Ethernet networking Version 1.1 EN, 12/2014, D5310.EN .01 Copyright © 2014 by d&b audiotechnik GmbH; all rights reserved. d&b audiotechnik GmbH Eugen-Adolff-Strasse 134, D-71522 Backnang, Germany Telephone: +49-7191-9669-0, Fax: +49-7191-95 00 00 E-mail: [email protected], Internet: www.dbaudio.com Contents 1. Introduction.......................................................4 2. Network topology............................................4 2.1. Network switches vs. network hubs..................................5 3. Identification and communication......................5 3.1. MAC address......................................................................5 3.2. IP address.............................................................................5 3.2.1. IP subnet masking............................................................5 3.2.2. Private networks...............................................................6 3.2.3. Automatic vs. manual assignment of IP addresses.....6 3.2.4. Hybrid IP address assignment schemes.......................6 3.3. Data transport via TCP and UDP......................................7 3.3.1. Ports...................................................................................7 3.4. Firewalls & security measures............................................7 3.4.1. Manual configuration guidelines..................................8 4. W-LAN (“Wi-Fi”)................................................8 4.1. Standards.............................................................................8 4.2. Channels and frequencies.................................................8 4.3. How to find a free W-LAN channel.................................8 4.4. “Line of sight” and the Fresnel zone.................................9 4.5. Wireless because “we can“?............................................9 5. Quick start........................................................9 6. Network hardware and cabling......................10 7. Further resources............................................10 8. Network topology examples..........................10 d&b TI 310 Ethernet networking (1.1 EN) 3 1. Introduction Ethernet-based networks are a method of choice for transporting content, as well as controlling data, in the entertainment industry. Some topological and administrative schemes are highly complex in that they require university grade knowledge on the subject matter, something that is beyond the scope of this tutorial. However, the vast majority of networking tasks and sizes are on productions that are smaller than national and world tours and can therefore easily be handled with a basic sound knowledge on the following issues: – How to set up a working network topology. – MAC and IP addresses and IP subnet masks. – How to set up the computer's network adapter. – How W-LANs work. – Network security. With copper based segments, the maximum length is limited This document is intended as a beginner's guide providing to 100 m, depending on the type of cable used. To extend exactly this knowledge, though it does not replace a the maximum distance to be bridged, additional switches or qualified network specialist. hubs may be inserted along the way to gain an additional segment length of 100 m each. Another way to extend the 2. Network topology length of a network segment is to use media converters and fiber optic connections. These allow for distances of up to Typically, Ethernet based networks comprising more than tens of kilometers. two hosts ('host' is the technical term for a network enabled device) employ a star topology. This means that all hosts The following illustration shows both options. The distance to are interconnected by one or more central switches or hubs. be bridged is about 300 m. With copper based segments, The switches and hubs themselves may also be two additional switches or hubs are required along the line interconnected to form a larger network. The connection involving all the associated issues: they all must be powered between two hosts can be referred to as a segment. and they all represent points of failure. The use of media converters and fiber optics, however, allows for one long Even devices that seem to have daisy chain capabilities in piece of fiber to connect both locations. that two connectors are supplied and labeled 'in' and 'out', simply have a small built in three port switch with two ports being visible from the outside, while the actual device is connected to the third internal port. Under no circumstances should any rings be created in the network, unless it is certain that the respective equipment supports this feature and is configured correctly. On the other hand, it makes sense to physically subdivide networks by using several switches as distribution units. The following illustration shows a typical example of two interconnected star networks. d&b TI 310 Ethernet networking (1.1 EN) 4 2.1. Network switches vs. network hubs Currently, with IPv4 as the predominant standard, IP Although a switch is by far the most commonly used device addresses are 32 bits long and are usually written in dotted to form a simple network, there are still a few network hubs decimal notation, with four decimal numbers ranging from 0 in use. The crucial difference between a switch and a hub is to 255. Each of those four decimal numbers represents that a hub just acts as an electronic repeater. All data that is 8 bits, which is why they are also sometimes called octets received on one port is transmitted to all the other ports. for example: This causes a lot of excess network traffic and includes all 137.152.89.230 the associated problems that cumulatively make the network perform less efficiently. The majority of the time this is what the usual user will have to deal with. 3.2.1. IP subnet masking To add to the complexity, the IP address is subdivided into a network prefix and the actual host number (also called the 'host part'), similar to a dbCAN network where a distinction is made between the subnet and the actual ID, for example: the CAN ID '5.23' can be separated into the subnet '5' and the ID '23'. In case of an IP address, however, there is no fixed number of digits to identify the network prefix or the host part. Instead, the network prefix of the IP address is defined by the subnet mask. As this can be a rather complex matter, it should be enough to look at a simple example that is easy Hub vs. switch: Host 'A' communicating with host 'C' to understand. In this example, the subnet mask, whose A switch, however, 'learns' which host (i.e. MAC address) is notation is very similar to the notation of the IP address connected to which of its ports and will therefore only itself, looks like this: transmit data between the two correct ports. 255.255.255.0 3. Identification and communication This denotes that the first three octets define the network prefix and the last octet is the host number. All network hosts Ethernet networks contain hosts of many different types from that are to communicate with each other without any different manufacturers. Common standards are required for additional 'help' from the network need to have the same identification and communication. The most relevant will be network prefix. described here. With the subnet mask above, such an IP address could look 3.1. MAC address like this: This has nothing to do with a popular brand of personal 192.168.0.[x] computers. Rather, it is a means to assign a unique identifier to a network host that may need to be addressed directly. where [ x] is the host number and '192.168.0.' would have to be identical for all hosts as it denotes the network prefix. MAC stands for ' Media Access Control'. The MAC address All hosts would be required to have '255.255.255.0' set as is implemented in the hardware of every network host (e.g. the subnet mask in their preferences. a d&b R70 Ethernet to CAN interface, the computer's network adapter, a wireless router, etc.) by the This would allow for up to 256 (0 to 255) different hosts manufacturer and is both unique and, at least in theory, (= devices) to be addressed. In reality, the lowest and unchangeable. highest possible host numbers, in this case '0' and '255' are reserved. This reduces the usable number of hosts to 254 in In Ethernet networks, the MAC address is 48 bits or 6 bytes the example, i.e. there may be up to 254 different long, and is usually written in hexadecimal notation for computers or other network enabled devices in the network. example: This should still be more than enough for any standard 00:41:80:AD:FC:2C application. A normal network user rarely comes into contact with the MAC address. 3.2. IP address Aside from the MAC address as a unique hardware identifier, network hosts must be grouped together to form logical networks. To this end, each MAC address (i.e. host) is assigned an IP address. In contrast to the MAC address, the IP address is not exclusive to a specific piece of hardware, but is assigned on a per use basis as needed. d&b TI 310 Ethernet networking (1.1 EN) 5 3.2.2. Private networks Note:: Each network should not include more than From the entire range of possible IP addresses, not all are one DHCP server, as this can lead to confusion and free for use. The vast majority of IP addresses are loss of communication. For technical reasons, this may administered centrally by the Internet Assigned Numbers also happen several hours or even days after a second Authority (IANA). However, there are a few address ranges DHCP server has accidentally been added to the that are reserved for private or ‘closed’ networks without network. Bear in mind that every device or computer any direct connection to the internet, which can be used sharing its internet connection is simultaneously a DHCP within such networks at will. These are the appropriate server, so care must be taken. address ranges for a production environment. The two most Even when used correctly, there can be drawbacks to commonly used ranges are: DHCP.
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