Codes Apply for Electromagnetic Locks

An electromagnetic lock (EM Lock) is essentially an electromagnet in a housing mounted on the door frame, and a steel armature mounted on the door wing. When the magnet is energized, it bonds to the armature and locks the door. To allow access or egress, a switch must be provided to de-energize the electromagnet. It can be difficult to determine which set of code requirements to follow. However, code compliance is crucial when this product is used in an access- or egress-control system. Unlike most locks, electromagnetic locks typically require external release devices such as motion sensors or request-to-exit switches to allow building occupants to exit. In addition, secondary means of releasing the mag-lock are often mandated by the codes, and the requirements vary depending on the type of locking system used.

Prior to the 2009 edition of the International Building Code (IBC), the set of code requirements typically used for doors equipped with electromagnetic locks was the section called Access-Controlled Egress Doors. The 2009 edition added a second set of requirements that could be used, called Electromagnetically Locked Egress Doors. Either of these two sets of requirements can now be used, depending on the application.

The basic difference between these two sections is that the original section, Access-Controlled Egress Doors, required a sensor and push button as release devices, while the new section, Electromagnetically Locked Egress Doors, allows a door-mounted release device instead. This could be panic hardware or a latchset with a request-to-exit (RX) switch, or a bar with an electronic touch sensor.

A building could have several AHJs (Authorities Having Jurisdiction), and more than one code may be enforced for a particular project. The most commonly used model codes in the U.S. are the International Building Code (IBC), the International Fire Code (IFC), and NFPA 101 – The Life Safety Code, but state and local codes sometimes include modifications that affect the use of electrified hardware. It’s usually best to follow the most stringent set of requirements that have been adopted in the project’s jurisdiction.

Here is a summary of the requirements for both sections from the 2009 IBC:

1008.1.4.4 Access-Controlled Egress Doors

·        Applies to entrance doors in a means of egress and entrance doors to tenant spaces.

·        Allowed in Use Groups - A (Assembly), B (Business), E (Educational), I-2 (Institutional - Hospitals & Nursing Homes), M (Mercantile), R-1 (Residential - Hotels, Motels, & Boarding Houses), and R-2 (Residential - Apartments & Dormitories).

·        A sensor must be mounted on the egress side to detect an occupant approaching the doors. Doors must unlock upon a signal from the sensor or loss of power to the sensor.

·        Loss of power to the lock must unlock the doors.

·        A manual unlocking device (push button) shall result in direct interruption of power to the lock – independent of the access control system electronics. When the push button is actuated, the doors must remain unlocked for 30 seconds minimum. The push button must include signage stating “Push to Exit” and must be located 40” to 48” vertically above the floor and within 5’ of the doors. Ready access must be provided to the push button.

·        If the building has a fire alarm/sprinkler system/fire detection system, activation of the system must automatically unlock the doors. Doors must remain unlocked until the system has been reset.

·        Entrance doors in buildings with an occupancy in Group A, B, E or M shall not be secured from the egress side during periods that the building is open to the general public.

1008.1.9.8 Electromagnetically Locked Egress Doors

·         Applies to doors in a means of egress and doors to tenant spaces. The 2009 IBC includes a limitation to doors “not otherwise required to have panic hardware,” which was removed in the 2012 edition.

·        Allowed in Use Groups - A (Assembly), B (Business), E (Educational), M (Mercantile), R-1 (Residential - Hotels, Motels, & Boarding Houses), and R-2 (Residential - Apartments & Dormitories).

·          The door must be equipped with listed hardware mounted on the door leaf, which incorporates a built-in switch to directly release the electromagnetic lock and unlock the door immediately.

·         The release device must have an obvious method of operation, and must be readily operated with one hand under all lighting conditions.

·            Loss of power to the listed hardware must automatically unlock the door.

·          When the new section was added to the 2009 IBC, the technical committee made a change to the proposed language which caused some confusion. A limitation to doors that are “not otherwise required to have panic hardware” was included in the 2009 edition, but it appears that this was not the intent. The limitation was removed and the intent clarified in the 2012 edition of the IBC, and as long as the switch in the panic bar releases the mag-lock, a door required to have panic hardware can be equipped with a mag-lock.

·        With the addition of Section 1008.1.9.8 – Electromagnetically Locked Egress Doors, the door-mounted release device can be used instead of the sensor and emergency push button. Note that this section does not require the mag-lock to release upon activation of the fire alarm or sprinkler system when a door-mounted release device is used. But there are a few issues that are still unclear, even with the 2012 changes.

·           The door must unlock upon loss of power to the “listed hardware,” which in this case is the door-mounted release device. Loss of power to some types of request-to-exit switches will not unlock the mag-lock. We may see a future change to the language so that loss of power to the electromagnetic lock is required to unlock the door, but the code currently addresses the release device.

·        I-2 occupancies (Institutional – Hospitals & Nursing Homes) are not included as acceptable locations for electromagnetically locked egress doors. This use group was added to the Access-Controlled Egress Doors section in the 2009 edition of the IBC, so hopefully the new section will catch up and include the I-2 use group in the future.

·        UL 305, the UL Standard for Panic Hardware, doesn’t address the use of panic hardware to release an electromagnetic lock. There is also a section of the IBC which states that certain doors shall not be equipped with a latch or lock unless it’s panic hardware. This should be changed to reflect the use of a mag-lock released by panic hardware.

The following summaries address each type of system where a mag-lock might be used, and the related model code requirements:

Sensor Release: A sensor automatically unlocks the electromagnetic lock to allow egress.

This is the most common type of system where electromagnetic locks are used. In past editions of the model codes, the applicable section referred to “access-controlled egress doors” which often gave the impression that the requirements applied to all doors with an access control system. A typical access control system which controls access but utilizes a lever handle or panic hardware to allow free egress is not required to comply with this section. The intent is for this section to apply only to electrified locks that are released by a sensor, and the title of this section has been changed in the model codes to clarify the intent.

For these systems, a sensor on the egress side of the door opening must detect an approaching occupant and unlock the door. The door must also unlock upon loss of power to the sensor or locking system, upon activation of the building fire alarm or automatic sprinkler system (until manually reset), and upon actuation of an auxiliary switch – typically a push button. This switch must be located 40-48 inches above the floor and within 5 feet of the door, must be readily accessible, and must be marked “PUSH TO EXIT.” Pushing the button must directly interrupt power to the lock, independent of the other electronics, and the door must remain unlocked for at least 30 seconds.

Recent editions of the IBC/IFC and NFPA 101 include virtually identical egress requirements for these systems, and all of these model codes currently require the UL 294 listing for these applications. It’s important to note that when this type of system is installed on a door that is required by code to have panic hardware, the panic hardware is required in addition to the electromagnetic lock.

Door-Hardware Release: A switch in the door-mounted hardware releases the electromagnetic lock to allow egress.

This type of system typically utilizes a request-to-exit (RX or REX) switch in the lever handle, panic hardware, or sensor bar mounted on the door. Again, the requirements of the IBC/IFC and NFPA 101 are very similar. The model codes require the hardware mounted on the door to have an obvious method of operation, and to be readily operable with one hand and under all lighting conditions. Operation of this door-mounted hardware must directly interrupt power to the electromagnetic lock, and the door must unlock immediately. The door must also unlock upon loss of power to the locking system, and the UL 294 listing is required by the current model codes. Note that this section does not require an auxiliary push button beside the door, or for the door to unlock upon activation of the fire protection system, although some local codes or AHJs may mandate these additional safety overrides.

Delayed Egress: Doors are locked to delay egress for 15 seconds under normal operation but allow immediate egress during an emergency.

There are two types of egress:

·        Free means that someone can exit an egress door without any delay by using only a single motion, such as turning a lever or pushing on a panic bar.

·        Delayed means that there’s a timed delay before someone can pass through the egress door and exit. Typically, this delay is 15 seconds.

Delayed egress is used to:

·        Discourage casual use of certain doors, so pedestrians can’t leave a premises or steal merchandise.

·        Deter elopement of patients, children or inmates from a protected area of a facility.

·        Make possible access control in both directions through selected openings.

Often, delayed egress systems include panic hardware with delayed egress circuitry, but electromagnetic locks are also available with this function. The lock includes an integral timer which allows the door to be opened 15 seconds after an attempt to exit is made – or 30 seconds when approved by the AHJ. The activation switch may be part of the mag-lock, or the timer may be initiated by an external RX switch.

To ensure free egress in an emergency, delayed egress locks must unlock immediately (no 15-second delay) upon activation of the fire protection system or sprinkler system, and upon loss of power. The capability of allowing immediate egress by a switch at the fire command center or other location may also be required.

Under normal operation, the delayed egress lock prevents egress until a force of 15 pounds, maximum, is applied for not more than 3 seconds; an audible alarm will sound in the vicinity of the door, and in 15 seconds the door will unlock to allow egress. After the device has been released by an attempt to exit, it must be rearmed manually - current codes do not allow delayed egress locks to rearm automatically.

Doors with delayed egress locks must also include signage stating, “PUSH UNTIL ALARM SOUNDS. DOOR CAN BE OPENED IN 15 SECONDS.” When a delayed egress lock is installed on an inswinging door, or when an AHJ approves a 30-second time delay, the signage must reflect the applicable operation. Specific requirements for the signage can be found in the model codes, and current codes also require the UL 294 listing for delayed egress locking systems.

The model codes include some additional limitations based on the use group or occupancy classification. For example, past editions of the IBC/IFC prohibited the use of delayed egress locks in assembly, educational, and high hazard occupancies, but the 2018 editions include exceptions for doors serving classrooms with an occupant load of less than 50 people, and for secondary exits from courtrooms. Delayed egress locks are allowed in those locations when the jurisdiction has adopted the 2018 edition of the model code, or when approve by the AHJ.

Controlled Egress: In health care facilities where patients require containment for their safety or security, doors may be locked in the direction of egress under normal operation but must allow emergency egress.

The IBC and IFC allow this application to be used in some health care units in hospitals, nursing homes, and other Group I-1 and I-2 facilities. These units might include memory care, maternity, pediatrics, or other areas approved by the AHJ. NFPA 101 includes these requirements in the chapters that cover new and existing health care facilities, and the code allows the doors to be locked where patients’ special needs require specialized protective measures for their safety or security.

According to the IBC and IFC, the building must have an automatic sprinkler system or automatic fire detection system, and activation of these systems must unlock the doors to allow egress. Loss of power must also automatically unlock the controlled egress doors, as well as a switch that directly breaks power to the lock - located at the fire command center, nurses station, or other approved location. A building occupant must not be required to pass through more than one door equipped with a controlled egress lock before entering an exit. The automatic-release requirements listed here do not apply to areas used for psychiatric treatment, or hospital units where listed infant abduction systems are installed.

All clinical staff members must have the ability – including keys or credentials – to unlock the doors for emergency egress, and these procedures must be included in the facility’s emergency plan. Training and drills are crucial in order for staff to be familiar with the egress protocols. Systems used for controlled egress must be listed to UL 294, and emergency lighting must be present at doors equipped with these locks. The requirements of NFPA 101 would not change the type of locks used in these systems (fail safe electrified locks), but the Life Safety Code does include slight variations to the required safety systems and procedures.

Stairwell Reentry: Stairway access doors may be locked on the stair side but must unlock to allow building occupants to leave the stairwell if it becomes compromised during a fire.

The IBC and IFC require all stairwell doors that are lockable on the stair side to have electrified locks that can be remotely released by a switch at the fire command center, or other approved location. (Note: Stair discharge doors may be locked to prevent access to the stairwell but must allow free egress.) For high-rise buildings, the IBC and IFC require the stairwell to be equipped with a two-way communication system if doors are electrically locked. Consult the IBC/IFC for exceptions related to buildings with a single exit stair.

The NFPA 101 requirements for stairwell reentry differ from the IBC and IFC, so it’s very important to refer to the adopted code to verify what is required. For example, NFPA 101 allows doors to be mechanically locked on the stair side when serving four stories or less – the IBC and IFC require these doors to be electrically locked, or never locked. NFPA 101 also exempts some occupancies from the reentry requirements, and includes a section detailing the criteria for “selected reentry” – which allows some doors to be mechanically locked and others to allow reentry.

If mag-locks are used on fire-rated stair doors, the door must be equipped with additional latching hardware to maintain the fire rating. In addition, the mag-locks must meet the applicable requirements on the egress side – sensor release, door hardware release, delayed egress, or controlled egress. Fail-safe electrified locks or fail-safe trim for fire exit hardware is commonly used; fail safe electric strikes are not listed for use on fire door assemblies.

Elevator Lobby Egress: Doors secure the elevator lobby and prevent access to the tenant space but must allow emergency egress from the lobby.

Currently, the IBC and IFC require each elevator lobby to have code-compliant egress via at least one exit. This could include direct access from the lobby to an exit stairwell, or free egress from the lobby to a corridor that leads through a tenant space to an exit. This means of egress must not be restricted, except with a delayed egress lock (most occupancy types) or an exit alarm.

NFPA 101 does allow egress through elevator lobby doors to be restricted during normal operation, if the doors allow emergency egress. The application must be allowed by the applicable occupancy chapter. For example, Chapter 11 (Special Structures and High-Rise Buildings) allows elevator lobby exit access doors to be locked “in other than newly constructed high-rise buildings.” Therefore, this application would not be allowed by NFPA 101 in new high-rise buildings.

The building must have a fire alarm and sprinkler system, and the lobby must have a smoke detection system. Activation of any of these systems (except by manual pull stations), or loss of power must automatically unlock the doors to allow egress. The doors must remain unlocked until the system is manually reset.

The elevator lobby must have a two-way communication system connected to a central control point that is constantly staffed by people who can provide emergency assistance. The electrified hardware must be listed to UL 294, and any latch-releasing hardware on the door must comply with the egress requirements of NFPA 101.

Because the IBC and IFC do not include a section similar to NFPA 101 regarding elevator lobby doors, some cities and states have modified the IBC/IFC to allow these doors to be electrically locked. These modifications typically require fail safe locks which unlock automatically upon activation of the fire protection system, as well as communication between the elevator lobby and a security desk or other location.

Security Interlock: Two or more doors are interlocked so that when one door is opened, the other door cannot be opened; commonly used on clean rooms and high-security applications.

Mag-locks are often used in security interlocks, but this application is not currently addressed in the model codes except when related to a prison sallyport. This type of system could impede egress, so each application must be approved by the AHJ, and additional safety features may be required. For example, to avoid entrapment in the room or vestibule, the AHJ may require emergency override switches in both locations, as well as an override switch on the exterior that is controlled by a key or credential. These switches will allow the doors to be unlocked for access or egress if one door is in the open position, preventing the use of the other door. In most security interlocks, the locks are automatically unlocked upon activation of the fire protection system, to allow free egress. Consult the AHJ to determine what is required.

In most cases, only one of these sections will apply to a particular door opening equipped with a mag-lock. The exception would be a stairwell door that must meet the stairwell reentry requirements on the stair side but would have one of the other applications on the egress side. Remember, refer to the applicable model codes and any state or city modifications to determine whether additional limitations apply, and consult the AHJ if more information is needed.

Code Comparisons - Occupancy Classifications

I-Codes. Until the 2018 edition of the IBC, delayed-egress locks were allowed in all use groups except A – assembly, E – educational and H – high hazard. Beginning with the 2018 edition, delayed-egress locks are allowed on the secondary exits that serve courtrooms (typically assembly occupancies) if the building has a sprinkler system. The 2018 edition also allows delayed-egress locks on classroom doors in educational occupancies if the calculated occupant load served by the door is fewer than 50 people. This gives schools an option if they’re looking for a way to prevent elopement of young children or students who have special needs.

NFPA. The NFPA codes are less restrictive and allow delayed-egress locks in areas of low and ordinary hazard contents, although the Life Safety Code includes restrictions depending on the occupancy. For example, delayed-egress locks aren’t permitted on the main entrance or exit doors that serve assembly occupancies, and they also are prohibited on airport jetway doors. Lodging or rooming houses can have only one door that has a delayed-egress lock per escape path, and residential board and care facilities are permitted to have delayed-egress locks only on exterior doors. The other occupancy classifications aren’t subject to similar limitations.

Code Comparisons - Required Fire Protection System

I-Codes & NFPA. Both sets of model codes require buildings that have delayed-egress locks to be equipped throughout with an automatic sprinkler system or approved automatic smoke- or heat-detection system. This requirement allows either type of system, although the change to the 2018 IBC that applies to courtrooms specifically requires a sprinkler system.

Code Comparisons - Activation Time

I-Codes & NFPA. Both sets of model codes require the delayed-egress timer to begin when a force of 15 pounds is applied for no more than 3 seconds. Prior to the 2015 edition of the IBC, the timer was required to begin after someone attempted to exit for 1 second. The activation time required to initiate the 15-second (or 30 second) timer is permitted to be less than 3 seconds, but it can’t be more than 3 seconds.

Code Comparisons - Automatic Release Delay

I-Codes & NFPA. When the timer is activated, the model codes require the delayed-egress lock to release in the direction of egress after 15 seconds; the AHJ might approve a time delay of 30 seconds. After that period, the door will be unlocked in the direction of egress, and another attempt to exit will allow the door to be opened.

Code Comparisons - Rearming After Activation

I-Codes & NFPA. When the timer of a delayed-egress lock is activated and the lock allows egress after 15 (or 30) seconds, the model codes require the lock to be rearmed manually.

Code Comparisons - Audible Alarm

I-Codes & NFPA. Both sets of model codes require an audible alarm to sound when a delayed-egress lock is activated, but the codes don’t mandate a specific type of alarm. Some products incorporate a continuous alarm, while others have an intermittent sound or even a verbal countdown.

Code Comparisons - Signage Requirements

I-Codes. Signage must state "PUSH [PULL] UNTIL ALARM SOUNDS. DOOR CAN BE OPENED IN 15 [30] SECONDS.” These signs are required for doors equipped with delayed-egress locks (see exception for Group I) and must be mounted above and within 12 inches of the door exit hardware. Beginning with the 2015 edition, signage is required to comply with the visual character requirements of ICC A117.1 – Accessible and Usable Buildings and Facilities. In Group I – institutional occupancies, the AHJ may allow signage to be omitted for certain types of treatment areas.

NFPA. The required text for the signage is the same as that required by the I-Codes: “PUSH [PULL] UNTIL ALARM SOUNDS. DOOR CAN BE OPENED IN 15 [30] SECONDS.” The NFPA codes require signage for delayed-egress locks to be readily visible, with letters not less than 1 inch high, a stroke width of one-eighths of an inch and a contrasting background, durable and located on the egress side of the door adjacent to the release device.

Code Comparisons - Action Upon Alarm Activation

I-Codes. When the fire alarm or sprinkler system is activated, delayed-egress locks must allow immediate egress automatically. This ensures that building occupants can exit quickly during a fire.

NFPA. The NFPA codes are more specific regarding the types of system activation that must unlock the delayed-egress locks for emergency egress. These doors must unlock with no delay in the direction of egress upon the activation of a sprinkler system, not more than one heat detector or not more than two smoke detectors.

Code Comparisons - Remote Release

I-Codes. To allow immediate egress when necessary, the I-Codes require delayed-egress locks to be capable of being deactivated by a switch at the fire command center or other approved locations.

NFPA. Remote release isn’t mandated by the section of the Life Safety Code that addresses delayed-egress locks.

Code Comparisons - Action Upon Power Failure

I-Codes & NFPA. When power fails, both sets of codes require delayed-egress locks to unlock immediately in the direction of egress. A common question about delayed-egress locking systems is whether battery backup is allowed in the power supply of the electrified hardware. The model codes don’t address this specifically, so it often is left up to the AHJ to decide whether delayed-egress locks must release upon loss of the main power to the building or continue to delay egress on standby power. However, based on the requirements of NFPA 72 – National Fire Alarm & Signaling Code, I don’t recommend using independent battery backup in the power supply of the delayed-egress lock. If the fire-alarm system and delayed-egress locks are powered by two different standby power systems, the hardware might not interface properly with the fire alarm after the loss of main building power. Using the same standby power source for the fire-alarm system and delayed-egress locks is preferred.

Code Comparisons - Emergency Lighting

I-Codes & NFPA. Emergency lighting is required by both sets of model codes, on the egress side of the door on which a delayed-egress lock has been installed. It’s important to check for the presence of emergency lighting before you install delayed-egress hardware.

Code Comparisons - Quantity of Locks per Egress Path

I-Codes. For most use groups, only one delayed-egress lock is allowed per egress path. This has changed from past editions of the I-Codes, where a building occupant could encounter only one delayed-egress lock before going through an exit. In Group I – institutional occupancies, such as hospitals, nursing homes and day care facilities, the I-Codes allow two doors that have delayed-egress locks per egress path, with a maximum combined delay of 30 seconds. In Group I-1, Condition 1 and Group I-4, the exception permitting two doors that have delayed-egress locks mandates that the building is equipped with a sprinkler system throughout.

NFPA. For most occupancy classifications, the NFPA codes don’t restrict the number of delayed-egress locks per egress path. Only in lodging or rooming houses does the Life Safety Code limit delayed-egress locks to one device per escape path.

Required Listings

I-Codes & NFPA. Both sets of model codes require delayed-egress locking systems to be listed to UL 294 – Standard for Access Control System Units. If a delayed-egress lock will be installed on a fire-door assembly, it also must be listed to UL 10C – Positive Pressure Fire Tests of Door Assemblies or NFPA 252 – Standard Methods of Fire Tests of Door Assemblies. In addition to the other listings, panic hardware that has delayed egress as a feature must be listed to UL 305 – Standard for Panic Hardware (I-Codes & NFPA) and in some cases BHMA A156.3 – Exit Devices (NFPA only).

If you are a system integrator or access automation installer or even a distributor, it is important to know how to select the best code application for access system on behalf of the customer. Majority of the datasheets and catalogues are not really useful unless you already know what you are getting into. If need any further information contact us on ssaintegrate@gmail.com.

Further Reading

For more on codes and delayed-egress locks:

IBC sections for Delayed Egress:

·        2021 – 1010.2.13

·        2018 – 1010.1.9.8

·        2015 – 1010.1.9.7

·        2012 – 1008.1.9.7

·        2009 – 1008.1.9.7

NFPA 101 sections for Delayed Egress Electrical Locking systems:

7.2.1.6.1

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.