How to choose a PoE switch for projects of various sizes. Case studies

Published on February 15, 2018

How to choose a PoE switch for projects of various sizes. Case studies

    Video surveillance, Wi-Fi networks and even cash registers: in our portfolio there are projects for which more than one hundred of our PoE switches were purchased. We want to tell you about the use of PoE equipment, some nuances in its selection - and the most delicious, we stocked up, of course, in the end.



    First, a few words about the technology and standards.

    A few words about PoE


    PoE (Power over Ethernet) allows you to transfer electrical energy to a remote device connected to the network via the Ethernet channel protocol (Ethernet / Fast Ethernet / Gigabit Ethernet). Power is transmitted over the same UTP (Unshielded Twisted Pair) cable.



    The main advantage of PoE is in lowering infrastructure costs. Of course, power equipment has a higher price (CAPEX), but the investment will quickly pay off during implementation and during operation (OPEX), especially when all associated costs are taken into account. For example, one cannot ignore the cost of pulling a power cable and installing additional outlets when using a traditional power scheme. In addition, this approach enhances the aesthetic component.

    The second advantage is the convenience of using end equipment powered through a single data cable.



    Power distribution using PoE allows you to centralize the management of the power supply system, monitor power consumption and enable / disable consumers, including automatically on a schedule. The result of centralization will increase the reliability and controllability of the entire system as a whole. So, for example, the network management system used in the organization can collect statistics on power consumption using the SNMP protocol.

    Another advantage of using PoE is security, as it provides intelligent power transmission that protects the terminal equipment from overload or lack of power.

    The flexibility provided by technology allows you to place powered equipment anywhere without being tied to electrical networks.

    Do not forget about the ease of installation and speed of network deployment. Less wired connections - shorter implementation times.

    To date, two standards for the transmission of energy over twisted pair are widely used in home and corporate networks, as well as in networks of telecom operators: IEEE 802.3af-2003 and 802.3at-2009. The main difference between them is the maximum transmitted power. The IEEE 802.3af-2003 standard provides power up to 15.4 watts (minimum 44 V and 350 mA) over two pairs of conductors, while when using IEEE 802.3at-2009 (also called PoE + or PoE plus), the maximum power increases to 25, 5 watts. Such enormous power may be required, for example, when using CCTV cameras with servo drive (rotary), or placed in specialized heated boxes.

    IP phones with additional control / extension panels may also not fit into the standard energy budget offered by the 802.3af standard. One cannot but mention the small switches appearing on the market, which themselves are capable of receiving power using PoE.

    However, not all of the indicated power is available to consumer devices. So, for example, when using the 802.3af standard at a distance of one hundred meters, only 12.95 watts will be available to the end device due to wire resistance and other losses.

    Successful projects


    Many corporate customers want to know the answers to a number of questions before buying the equipment of a vendor. Have you already had successful implementations? What equipment was used in what cases and why? How many devices are used? What is the coverage area? We will give some examples of the successful implementation of TP-Link equipment in the networks of some of our major customers, which were manufactured in 2016/2017, and also answer some of these questions.

    CCTV


    The task of powering cameras is one of the standard when using PoE switches. Our equipment is used by various retailers, including the X5 RETAIL GROUP. The Pyaterochka supermarket chain, owned by the group, has deployed a video surveillance system built on the basis of PoE switches TP-Link T1500-28PCT. This model is designed for installation in a telecommunication rack, has 24 powered Fast Ethernet ports, four Gigabit Ethernet connectors and two combined gigabit SFP-slots. Strengths of the switch can also include built-in protection and traffic prioritization functions. Initially, Pyaterochka started building infrastructure with competitor 16-port switches, but then they drew attention to our 24-port models of similar price, which in the end helped the company significantly save due to the larger number of connected cameras.


    TP-Link T1500-28PCT

    PoE technology was also used in this project to provide power to some access points and VoIP phones. And other equipment (servers, printers, network security devices) was connected using the usual Gigabit Ethernet interfaces. In total, about 2,000 of our supply switches were installed in supermarkets of the network.

    Another large federal chain of stores for home and summer cottages also built its video surveillance system based on the T1500-28PCT model: The 180-watt energy budget was ideally suited to their requirements. Typical internal cameras for video surveillance belong to the second class of powered devices in terms of the IEEE 802.3af standard and fit into the range of power consumption from 3.8 to 6.5 watts. Their CCTV system used internal fixed camera models (without servos and heated casings), which made it possible to provide them with power even using switches that did not have the maximum energy budget.

    We have another example of the successful large-scale implementation of our PoE switches. In this case, we are talking about the model T2600G-28MPSwhich has up to 384 watts of power for 24 gigabit PoE ports. Based on this switch (together with TRASSIR), a video surveillance system was deployed in a network of family hypermarkets (in total, the customer needed about 750 PoE + switches to build a large-scale video surveillance system).

    Video surveillance on the exam


    One of the special applications was the organization of video surveillance during the exam in 2017. For this purpose, we provided T1600G-28PS switches : 24 gigabit PoE + ports with support for 802.3at / af standards and an energy budget of 192 watts. The choice on the T1600G instead of the T1500 fell due to the gigabit ports that the installed video cameras also had.


    Photo: opennov.ru

    The difference between the T1600G-28PS and T2600G-28MPS is that the former has a lower energy budget, but is more preferable in price.

    Networks in universities


    In general, university networks are interesting for their heterogeneity. Here we would like to mention projects in two large educational institutions of our country. In both cases, T2600G-28MPS switches (TL-SG3424P) with a large energy budget (up to 390 W) were used. These switches belong to the JetStream line of level 2+ and have 24 copper gigabit ports with PoE + 802.3at / af support, as well as four SFP-slots. The maximum performance of the device is 56 Gbps or 41.7 million packets per second. Model T2600G-28MPS can be installed in a 19 "telecommunication rack or placed on a table or shelf.

    In the first case, a large-scale video surveillance system was deployed, the technical task for which required the installation of switches with an energy budget of at least 380 watts. Also in this case, it was necessary to ensure security already at the level of network access. Both of these conditions determined the choice of model.



    In the territory of another educational institution, T2600G-28MPS switches were used to organize a wired segment that supports the operation of a wireless Wi-Fi network. This model was chosen because the power consumption of access points is significantly higher than standard IP cameras.



    Wireless functions were assigned to the TP-Link AC500 controller and the CAP1750 access points, which we already talked about in detail in our blog earlier.

    Examples of building small networks


    Of course, compact models with PoE, designed to work outside specialized server ones, also enjoy success. For example, fanless TL-SG108PE . This switch has eight gigabit ports, four of which provide power to connected equipment (up to 15.4 watts per port). The total PoE budget of the device is 55 watts. It is these switches that were used to build local networks in the federal retail network of shoe stores and another popular pharmacy chain. In both cases, our PoE switches were used to power surveillance cameras and provide access points with electricity to create Wi-Fi networks, also built on TP-Link.



    Delicious: from non-standard


    We also have non-standard applications. One of the non-trivial projects was carried out jointly with CloudKassir . In July 2017, a law entered into force requiring online stores to make payments through cash desks and issue electronic checks. The real-time tax office sees the revenue of the business, and the buyer always has a document confirming the transaction on hand.

    At the heart of all this are cash registers connected to the Internet. The seller can place such a cash desk at home, provide power, access to the global network, and so on. But it can also use the service of specialized companies that provide cash from the cloud for rent. In the construction of one of these services, we took part. It is worth noting that the decision was made at the time of an acute shortage of cash registers, which was the reason for some of the adopted technical solutions.

    The network is based on TP-Link T1600G-52PS switchesrack mounted. This model not only performs traffic switching, but also provides cash registers with power. Unfortunately, the cash desk models used did not support Power over Ethernet technology (and indeed were not intended for rack mounting), so I had to supplement the structure with PoE-splitters located along with online cash desks on specialized drawer shelves mounted in a standard telecommunication rack.



    The applied solution made it possible to obtain a gain in the used space inside the rack (due to the lack of traditional power supplies), as well as to provide greater flexibility in controlling the power system. The compactness of the solution in the future will save on the rental of racks and, in general, increase the efficiency of the customer’s IT system.

    The non-standard solution in this case is that PoE is used inside the server rooms of the data center, where there is usually no shortage of power supply, and the equipment installation density is quite high.

    In the dry residue


    As we can see, equipment with PoE is often used to organize large-scale video surveillance systems and to provide wireless access to the network in large areas. And here everything is logical, but there is one point: in our practice, the choice of equipment of one or another manufacturer in Russian projects is often determined by the degree of involvement of the vendor in the project itself. And we are talking here not only or not so much about warranty or support (for some models we have a limited lifetime warranty, in some cases we can offer a free advanced replacement), but about the flexibility of the manufacturer's approach to projects using its equipment.

    For example, in a number of projects, the main role in choosing equipment was played by customization of the firmware of devices. Also, the possibility of free preliminary testing of equipment does not go unnoticed. Well, a full-fledged radio-frequency survey and planning, carried out at the stage of project development, provided the choice of our wireless equipment in universities. In other words, we tried.

    In conclusion, we would like to help you understand the model range of our switches and provide explanations on the numbering of models. For example, consider the T2600G-28MPS switch.

    The number after T indicates the control level: 1 - Smart, 2 - managed switch L2 / L2 +, 3 - switch with third-level functions.

    For managed switches, the second digit in the model name means the basic set of firmware functions and the hardware platform: 5 - standard L2-functions, 6 - support for static routing, 7 - the presence of 10 Gigabit Ethernet interfaces or support for physical stacking.

    The letter after the numbers indicates the main port speeds: G - Gigabit Ethernet, X - 10 Gigabit Ethernet, the absence of a designation indicates that the switch interfaces support Fast Ethernet.

    The total number of ports is encoded in the second group of digits.

    The last set of letters is used to indicate the type of interface and other hardware characteristics: T - UTP ports, P - switch with PoE support, MP - switch with an increased energy budget, S - independent SFP Uplink ports and so on.

    From the above it turns out that the T2600G-28MPS model is a TP-Link managed L2 / L2 + switch with static routing support and an increased energy budget, with 28 ports operating at 1 Gb / s, and also with independent Uplink interfaces, designed to install SFP.

    A comparative overview of all models is always available here.