Difference between Hub and Switch

Difference between Hub and Switch 

Network devices, or networking hardware, are physical devices that are required for communication and interaction between hardware on a TCP/IP network.

Here is the common network device list:

·        Hub

·        Switch

·        Router

·        Bridge

·        Gateway

·        Modem

·        Repeater

·        Access Point

In 2006 The Network Hub is invented at Vancouver, British Columbia, Canada. A hub is a device that connects multiple Ethernet devices on one network and makes them act together as a single network. A hub does not gather information and input in one port results as an output in all ports on the network. A switch is a networking device that performs the same job as the hub but are considered as a more intelligent hub as it gathers information about the data packets it receives and forwards it to only the network that it was intended for. A Hub is a layer-1 device and operates only in the physical network of the OSI Model.

Hubs and switches are devices that are used in data networking on the internet. These devices are used in order to connect two or more networking ports in order to transfer data along the connection. Though the primary job of hubs and switches are the same, to forward data to different networks, they work in different ways.

A hub, also known as Ethernet hub, active hub, network hub, repeater hub or multiport repeater, is a device that connects multiple Ethernet devices on one network and makes them act together as a single network. A hub has multiple input/output (I/O) ports, in which an input in one port results in it being an output in all the other ports, except the port where it was input. In layman’s terms, a hub connects many networks into one, where a data packet that is sent by one networks, is copied and pasted to all network ports, making it so that every port can see that data packet. A hub works on the physical layer or layer 1 of the Open Systems Interconnection (OSI) model. It also works as a data collision detector, sending a jamming signal to all ports if it detects collisions at one port.

It is a simple device that does not examine the data it receives or sends, while just duplicating the data and making it visible for all. The receiving port that has to decide if the data packet is actually intended for it by checking the address on the packet, before passing it on further. Since hubs only have one collision domain, constant collisions occur. Unnecessary traffic is sent to all devices on the network. Originally hubs were popular due to the high price of switches, but switches are not so expensive these days. Hubs are slowly becoming obsolete in many practices, but are still used in special circumstances.

A switch is a networking device that performs the same job as the hub; it connects network segments or devices making them act as a single network. Switches are commonly referred to as a multi-port network bridge that process and routes data on a data link layer or layer of the OSI model. Switches can also process data at the network layer (layer 3) or higher layers and are known as multilayer switches.

Switches are considered as a more intelligent hub as it gathers information about the data packets it receives and forwards it to only the network that it was intended for. When a switch receives a data packet, it examines the data address, the sender and the receiver and stores the memory, after which it then sends the data to the device that the data is meant for.

Most modern Ethernet Local Area Networks (LANs) operate on switches. Small offices and residential devices commonly use single layer switch, while bigger applications require multilayer switches. The switches use a bridge or a router in order to split a larger collision domain to smaller collision domains, resulting in lesser collisions.  Each port has an individual collision domain, allowing computers to maintain dedicated bandwidth.

	Hub	Switch
Definition	A hub is a connection point for different segments of a LAN. It contains multiple ports and when it receives a packet of information at one port, it copies this packet to all segments of the LAN so that it can be viewed by all ports.	A switch is multi-port networking device that connects network devices together. A switch operates at the data link layer (layer 2) of the OSI model. A switch filters and then forwards data packets between networks.
Layer	Physical Layer (Layer 1)	Data Link Layer (Layer 2)
Spanning-Tree	No Spanning-Tree	It allows many Spanning-Trees to take place.
Type of Transmission	Broadcast	Broadcast, Uni-cast & Multicast.
Table	No MAC table. Hubs cannot learn MAC address.	Stores MAC address and maintains address.
Used in	LAN (Local Area Networks)	LAN (Local Area Networks)
No of Ports	4	24-48 depending on type of switch.
Collision	Occurs	No collision occurs
Collision Domain	One collision domain	Every port has its own collision domain.
Transmission Mode	Half duplex	Full duplex

Types of Hub

There are three types of the hub that are given below:

1.  Passive Hub

2.  Active Hub

3.  Intelligent Hub

Passive Hub: The passive hubs are the connection point for wires that helps to make the physical network. It is capable of determining the bugs and faulty hardware. Simply, it accepts the packet over a port and circulates it to all ports. It includes connectors (10base-2 port and RJ-45) that can be applied as a standard in your network. This connector is connected to all local area network (LAN) devices. Additionally, the advanced passive hubs have AUI ports, which are connected as the transceiver according to the network design.

Active Hub: As compared to a passive hub, it includes some additional features. It is able to monitor the data sent to the connected devices. It plays an important role between the connected devices with the help of store technology, where it checks the data to be sent and decides which packet to send first.

It has the ability to fix the damaged packets when packets are sending, and also able to hold the direction of the rest of the packets and distribute them. If a port receives a weak signal, but still it is readable, then the active hub reconstructs the weak signal into a stronger signal before its sending to other ports. It can boost the signal if any connecting device is not working in the network. Therefore, it helps to make the continuity of services in LAN.

Intelligent Hub: It is a little smarter than passive and active hubs. These hubs have some kinds of management software that help to analyze the problem in the network and resolve them. It is beneficial to expend the business in networking; the management can assign users that help to work more quickly and share a common pool efficiently by using intelligent hubs. However, it offers better performance for the local area network. Furthermore, with any physical device, if any problem is detected, it is able to detect this problem easily.

The important applications of a hub are given below:

·        Hub is used to create small home networks.

·        It is used for network monitoring.

·        They are also used in organizations to provide connectivity.

·        It can be used to create a device that is available thought out of the network.

Advantages of Hub

1. It provides support for different types of Network Media.

2.  It can be used by anyone as it is very cheap.

3.  It can easily connect many different media types.

4.  The use of a hub does not impact on the network performance.

5.  Additionally, it can expand the total distance of the network.

Disadvantages of Hub

1. It has no ability to choose the best path of the network.

2.  It does not include mechanisms such as collision detection.

3.  It does not operate in full-duplex mode and cannot be divided into the Segment.

4.  It cannot reduce the network traffic as it has no mechanism.

5.  It is not able to filter the information as it transmits packets to all the connected segments.

6.  Furthermore, it is not capable of connecting various network architectures like a ring, token, and ethernet, and more.

PoE NVR and PoE Switch

Difference between PoE NVR and PoE Switch?

Sir “I’m going to install two IP cameras in my house. However, I have no idea whether to use a PoE NVR or a PoE switch matching with them. So, what’s the difference between them? “

Hello “Arindam sir, this is XXX from BBB, as you are security expert, I realy confused from my cctv vendor, someone quote PoE based NVR someone quote PoE switch with Normal NVR. Please suggest which technology is best for us.”

Such type of questions I face throughout 2018, which indicates many people feel confused about the selection between PoE NVR and PoE switch. This write-ups / blog intends to explore the differences between PoE NVR and PoE switch in details.

What Is PoE?

PoE, an abbreviated form of Power over Ethernet, allows a single CAT cable connecting a power sourcing equipment (PSE) to provide both data connection and electric power to powered devices (PDs) such as IP cameras, wireless access points, etc.

What Is a PoE NVR?

NVR represents for network video recorder which provides you with centralized video controls to easily view, manage, and store your surveillance footage in one convenient location. A PoE NVR is a security video recorder with built-in PoE switch designed to use with PoE-based IP cameras.

Equipped with a PoE switch, a PoE NVR recorder can deliver both data and power over a single Ethernet cable. There is no need for an additional PoE switch, which will reduce the cost of equipment in theory. You just need to connect one Ethernet cable from the camera to the PoE NVR recorder and then the built-in switch will provide power to the camera while transmitting data.

A PoE NVR is ideal for users with minimal network administration experience and is generally used in homes and small businesses. It creates a private camera network, keeping surveillance footage isolated from the main network and adding an extra layer of privacy.

What Is a PoE Switch?

A PoE switch or power over Ethernet switch, containing multiple Ethernet RJ45 ports, is a dedicated network switch with multiple Ethernet ports to connect network segments and provide power and network communications.

It expands a network created by a router. Basically, it just assigns LAN IP addresses to your camera and needs to be tied into a system that allows you to see and manage your cameras, which is usually done with video surveillance software on a computer. Therefore, it must be connected directly to a router on the same network as your NVR. It can reduce the need for extra outlets and extension cables and saves deployment cost and labor efforts as well.

Power over Ethernet switch can be classified into many types. In addition to the most common one, gigabit PoE switch, for example, there are other types as well such as unmanaged and managed PoE switches. Most PoE switches provided in the market have standard gigabit Ethernet ports which can provide speed of 10/100/1000Mbps. For smaller network, 8-port Gigabit PoE switch is very popular. For larger/enterprise network, we use 24-port PoE switch and 48-port managed switch.

Main difference between a PoE NVR & PoE Switch

From the above, you will see that both PoE NVR and PoE switch can provide power and data transmission. However, the former is limited in minimal network administration experience while the latter can expend the network freely. What’s more, a switch does not assign IP addresses, which is the job of a DHCP server, usually built into a router. PoE NVRs provide this service, while PoE switches don’t. The switch simply provides a data path between all of the devices connected to it.

Note: You cannot plug a POE switch into an NVR directly - it must be plugged into your network.

Visit http://arindamcctvaccesscontrol.blogspot.com/2014/11/poe-network-camera-in-global-market.html for more detail.

Tips of Hanwha PoE NVR 

By default, PoE NVRs are set to connect directly to IP cameras.  In cases where the PoE ports are connected to network switches, the NVR must be put in Manual mode.

In addition, the PoE ports are set to Isolated mode, where each device can only communicate only with the NVR and not each other.  This is a security feature to prevent rouge devices from accessing other devices on the network.  This will prevent a connected PC from accessing IP cameras for setup changes.

If you are uplinking non-camera devices, such as switches, media converters, PCs, etc., you must set the NVR to Manual mode.

From the setup menu of the NVR, navigate to System > System Management > Settings > Load Factory Default.

Select the Manual Setup Mode.  If you wish to save some of the settings to speed up setup, check the Not Included options of User, Camera, and/or Network as needed.

Click the Initialization button and wait for the NVR to reboot.

This Write ups published on safe secure magazine Feb 2019 issue.

Selecting a PoE Switch

You just picked up some new Power over Ethernet devices – a few of the hottest new IP cameras. However, after opening the box you run into a series of unexpected problems. No its a really powerful decision.

First: Each camera comes equipped with its PoE injector capable of supplying the appropriate level of power.  However, prior to even mocking up your panel it becomes clear – four PoE injectors and a standard Ethernet switch will not fit.
In an effort to maintain a reasonable panel size, you ditch the PoE injectors in favor of a Power over Ethernet switch, a single product that will replace all four injectors and provide Ethernet switching.  So far so good.

Second: After deciding that a PoE switch will best suit your need, you set out on a search for the cheapest PoE switch you can find.  Before long you realize the injectors were provided so that the cameras receive the exact amount of power they are optimized to run at.  With this new concern in mind, the search moves from the “cheapest switch” to the ”right switch.” In order to identify the right switch, you will need some information… but where do you look?

You are able to find a small label printed on the bottom near the Ethernet port of the camera – something that specifies how this camera can be powered. Now you have some numbers to shoot for, but what exactly do they mean?

While listed on the label in the above order, Power over Ethernet is best addressed in this order:-

1.     Is this a Power over Ethernet device?

A.     Will the device accept Power and data through the Ethernet port? Has the device been designed to make use of Power over Ethernet.

2.     Is this device IEEE 802.3af or IEEE 802.3at compliant?

A.     How much power will the device draw? Both IEEE 802.3af and 802.3at are based off +48VDC voltage but differ in wattage.

B.     IEEE 802.3af = “Standard PoE” = devices consuming up to 12.95W of PoE power IEEE 802.3at = “PoE Plus, High-Power PoE” = devices consuming up to 25.50W of PoE power

3.     Which class of Powered Devices (PD) is the device a member of?

A.     PoE capability and power level compliance – the class level of Powered Devices further specifies how much power the device will draw

Class 1 = 0.44 – 3.84W “Very low power”
Class 2 = 3.84 – 6.49W “Low power” 
Class 3 = 6.49 – 12.95W “Mid power” 
Class 4 = 12.95 – 25.5W “High power, suitable only for IEEE 802.3at PoE”

Translating the above power label again we find:

1.     Is this a Power over Ethernet device? Yes, this camera can accept PoE

2.     Is this device IEEE 802.3af or IEEE 802.3at compliant? IEEE 802.3af – the maximum it will draw is 12.95W at 48VDC

3.     Which class of Powered Devices (PD) is the device a member of? Class 2 – this device will draw between 3.84 and 6.49W – it is a “low power” device

After finding a Power over Ethernet switch that will provide suitable power conditions on a per-port basis, there is one final element to consider – power budget.

Will the switch you choose provide enough power per port for each camera? You bought four cameras to use four cameras, not to use just one or two.  Your choice in a Power over Ethernet switch needs to reflect this… Will the switch provide suitable power to all ports at all times?

Finally, after considering space in your panel, power demands of one camera, power ability of a switch for one port, and powering ability of a switch across all ports, you are prepared to make a decision!

PoE network camera in Global market

Development of PoE network camera in Global market

Since the launching of Power over Ethernet (PoE) standard, global enterprise are eager to utilize this emerging technology in just a few years. According the latest survey, in just six years from 2008 to now, the annual increasing rate of power equipment with PoE technology will reach 33%. In 2014, global market of power devices with PoE technology will be over $5.2 billion, compound annual growth rate will be 38%.

Along with the development of worldwide security market, users start to consider deploying some network cameras and other network security devices. Network surveillance based on PoE is more and more accepted by users and have great development.

PoE (Power over Ethernet) means keeping the current Ethernet cat-5 deployment, assure interface AP for wireless network security cameras and other IP signal devise based on IP signal, at the same time, it is able to power ac electric for those kinds of devices. PoE technology use one general Ethernet cable to transmit Ethernet signal and ac electrical source simultaneously, allowing power and date to be integrated into the same cable system. In the case of guaranteeing the construction cable safety, keep normal answer operation. PoE network camera use PoE technology to realize the network video surveillance, which has power device function to use direct current main provided by power device equipment to transmit to power device via twisted-pair.

Compared to normal network camera, PoE network camera has following advantages: apart from power the connected device through Ethernet cable, PoE reduce the investment cost, as a result, it decrease the overall the deployment costs to  organize the device based on IP infrastructure. Poe not only provide the need for installing wall power connection, which dramatically reduce the plug costs related supporting end devices but also install the network connection device on the place where is hard to deploy the local alternating current power supply, to some content, provide more flexibility. We can separate PoE network camera form power device end in the practice, which can be divide into two types, normal cameras and PoE adaptor. Front end has Ethernet switch for PoE power, and back end has PoE adaptor, which will transmit the twisted cable power to network camera for the working power. Because power device is able to identify the rate of power, when we use ups to power, the advantage of saving energy is more obvious.

How fiber optic cabling combined with PoE converters allows long-distance IP camera placement

Power over Ethernet (PoE) technology enables powering IP surveillance cameras through the transfer of DC electrical power along with data over standard unshielded twisted pair (UTP) cabling. This cabling connects to a network device through an RJ-45 port that injects the power from power sourcing equipment such as a PoE switch or midspan PoE injector. PoE provides a flexible and convenient means of powering devices that are located in out-of-the-way locations, and saves money by eliminating the expense and difficulty of direct electrical wiring. A challenge with PoE is reaching remote locations outside the distance limitation of UTP cabling. According to the TIA/EIA 568-5-A standard for category 5e cable, the maximum length for a cable segment is 100 meters (328 ft), and PoE power injectors or midspans do not increase the distance of the data link.

So, how do you get beyond that 100-meter limit? Once answer is through fiber optics. Fiber optic cabling is an effective method to overcome the distance and bandwidth limitations of UTP, and media converters are a commonly used to integrate copper network equipment and fiber. Since DC power cannot be conducted over fiber, PoE media converters are the solution to extend network distances via fiber to remote IP cameras. A PoE media converter converts the fiber to copper, and sends DC power to the camera over the UTP cabling.

How PoE Media Converters Work
On the main article image/PoE schematic that appears at right, an Ethernet switch with RJ-45 ports resides in a control room or data closet. The copper UTP cabling is converted to fiber with a standard media converter. The fiber is run a long distance to the PoE media converter located near a convenient AC or DC power source, where it converts the fiber back to copper UTP. The PoE media converter also functions as a power-sourcing mini switch, and injects PoE (DC power) over the UTP cable. At the other end of the UTP cable is the IP camera, located up to 100 meters away from the PoE media converter.
PoE media converters are available with Gigabit Ethernet and Fast Ethernet data rates and can support PoE (15.4 watts) or PoE+ (25.5 watts). PoE media converters function like PoE mini-switches, and are available in a variety of multi-port configurations, including dual RJ-45 and dual fiber ports. They can support fixed fiber connectors or small form pluggable transceivers.
To understand those power specifications, it’s worth knowing that in 2003, the IEEE ratified the 802.3af PoE Standard. That standard provides up to 15.4 watts of power per port. Late in 2009, the IEEE ratified the 802.3at PoE Standard known as PoE+ that provides up to 25.5 watts of power for each port. PoE+ can be required to power IP cameras with Pan-Tilt-Zoom (PTZ) / Speed Dome Camera capabilities, and weather-hardened cameras used in cold environments that feature blowers and de-icers.

Leverage the Benefits of Fiber
There are several solutions available to extend the distances of PoE network links, including LAN extenders that convert Ethernet to DSL, UTP to coax converters and wireless technology. When you’re going long distance, however, fiber optic cabling provides several advantages over these technologies.
Unlike copper, fiber extends network distances up to 87 miles (140 kilometers) per link with no data deterioration over distance (signal deterioration is to be expected in copper cabling). LAN extenders can only extend network distances about 3,300 feet, but a data rate of 100 Mbps can drop by 70 percent at longer distances.
Fiber cabling provides security benefits as well. It is a secure medium that generates no electro-magnetic emission and is very difficult to tap. Fiber is also very reliable because it is not susceptible to electrical interference, or data loss due to temperature or atmospheric conditions.