HUB:
====
-> A hub is considered a layer one device of the OSI model;
-> all it does is send packets out on all ports including the port in which the packet was received on.
-> Hubs can also be referred to as repeaters
-> hubs will always forward every frame out every port, excluding the port originating the frame.
-> it do not differentiate between frame types, and thus will always forward unicasts, multicasts, and broadcasts.
-> Ethernet hubs operate at half-duplex.
-> If a collision is detected, the hub will discard the frames and signal the host devices.
-> all ports on a hub belong to the same collision domain. Multiple hubs that are uplinked together still all belong to one collision domain.
-> Increasing the number of host in a single collision domain will increase the number of collisions, which can significantly degrade performance.
-> Hubs also belong to only one broadcast domain.
Typical HUB
Bridge:
=======
-> A bridge is used to break larger network segments into smaller network segments.
-> It works much like a reapeater, but because a bridge works solely with Layer 2 protocols and layer 2 MAC sublayer addresses, it operates at the Data Link layer.
-> A bridge uses the MAC address to perform its tasks, including:
* Monitoring network traffic
* Identifying the destination and source addresses of a message
* Creating a routing table that identifies MAC addresses to the network segment on which they’re located
* Sending messages to only the network segment on which its destination MAC address is located
Bridge
Switch:
=======
-> A switch uses layer two of the OSI model,
-> switch uses MAC addresses to send the packet to the correct device.
-> Rather than sending it to all ports a switch only sends the packet out one port, if it has the MAC address in its MAC address table. If not the switch will send the packet on all ports except for the port in which the packet was received on.
-> it uses switch table.
-> it segments collision domains.
-> it is faster than router in LAN
-> Switches provide separate collision domains on each port. This provides dedicated bandwidth to that device.
This also allows simultaneous conversations between devices on different ports. Each port can be operated at full-duplex so the device can send and receive information at the same time
Switch
Router:
=======
-> it is layer 3 device of the OSI model.
-> it works based routing table.
-> it segments broadcast domains.
Layer 3 Device_Switch :-
================
does not support as many routing protocols as router does,
NATing and WIC configuration is not possible,
Help for inter VLAN routing only.
Bridging vs LAN Switching :
———————————
-> Layer-2 switches are really just bridges with more ports. However, there are some important differences you should be aware of:
* Bridges are software based, while switches are hardware based because they use an ASICs chip to help make filtering decisions.
* Bridges can only have one spanning-tree instance per bridge, while switches can have many.
* Bridges can only have up to 16 ports, whereas a switch can have hundreds.
HUB Switch Bridge Router
Network Devices And Its Symbol
vijayababuj 