Router vs Switch vs Hub: The Devices Defined
The functions of the three devices — the router,
switch and hub — are all quite different from one another, even if at
times they are all integrated into a single device. Which device do you use
when?
What is a Router?
A device that
forwards data packets along networks. A router is
connected to at least two networks, commonly two LANs or WANs or a LAN and its ISP.s network.
Routers are located at gateways, the places where
two or more networks connect. Routers use headers and
forwarding tables to determine the best path for forwarding the packets, and
they use protocols such
as ICMP to
communicate with each other and configure the best route between any two hosts.
What is a Switch?
In networks,
a device that filters and forwards packets between LAN segments. Switches operate
at the data link layer (layer 2) and sometimes the network layer (layer 3) of the OSI
Reference Model and
therefore support any packet protocol. LANs that use
switches to join segments are called switched LANs or, in the
case of Ethernet networks, switched Ethernet LANs.
Finally, what is a Hub?
A
common connection point for devices in a network.
Hubs are commonly used to connect segments of aLAN. A hub contains multiple ports.
When a packet arrives at one port, it is copied to
the other ports so that all segments of the LAN can see all packets.
The Differences Between a
Router, Switch and Hub on the Network
Today
most routers have become something of a Swiss Army knife, combining the
features and functionality of a router and switch/hub into a single unit. So
conversations regarding these devices can be a bit misleading — especially to
someone new to computer networking.
The
functions of a router, hub and a switch are all quite different from one
another, even if at times they are all integrated into a single device.
Let's start with the hub and the switch since these two devices have similar
roles on the network.
Hub vs Switch: Similar
Roles
Each
serves as a central connection for all of your network equipment and handles a
data type known as frames. Frames carry your data. When a frame is received, it
is amplified and then transmitted on to the port of the destination PC. The big
difference between these two devices is in the method in which frames are being
delivered.
In a hub, a frame is passed along or "broadcast" to every one of its ports. It doesn't matter that the frame is only destined for one port. The hub has no way of distinguishing which port a frame should be sent to. Passing it along to every port ensures that it will reach its intended destination. This places a lot of traffic on the network and can lead to poor network response times.
Additionally, a 10/100Mbps hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the maximum available bandwidth. If, however, multiple PCs are broadcasting, then that bandwidth will need to be divided among all of those systems, which will degrade performance.
A switch, however, keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to, without significantly increasing network response times. And, unlike a hub, a 10/100Mbps switch will allocate a full 10/100Mbps to each of its ports. So regardless of the number of PCs transmitting, users will always have access to the maximum amount of bandwidth. It's for these reasons a switch is considered to be a much better choice than a hub.
In a hub, a frame is passed along or "broadcast" to every one of its ports. It doesn't matter that the frame is only destined for one port. The hub has no way of distinguishing which port a frame should be sent to. Passing it along to every port ensures that it will reach its intended destination. This places a lot of traffic on the network and can lead to poor network response times.
Additionally, a 10/100Mbps hub must share its bandwidth with each and every one of its ports. So when only one PC is broadcasting, it will have access to the maximum available bandwidth. If, however, multiple PCs are broadcasting, then that bandwidth will need to be divided among all of those systems, which will degrade performance.
A switch, however, keeps a record of the MAC addresses of all the devices connected to it. With this information, a switch can identify which system is sitting on which port. So when a frame is received, it knows exactly which port to send it to, without significantly increasing network response times. And, unlike a hub, a 10/100Mbps switch will allocate a full 10/100Mbps to each of its ports. So regardless of the number of PCs transmitting, users will always have access to the maximum amount of bandwidth. It's for these reasons a switch is considered to be a much better choice than a hub.
Routers are Completely
Different Devices
Routers
are completely different devices. Where a hub or switch is concerned with
transmitting frames, a router's job, as its name implies, is to route packets to other networks until that packet
ultimately reaches its destination. One of the key features of a packet is that
it not only contains data, but the destination address of where it's going.
A router is typically connected to at least two networks, commonly two Local Area Networks (LANs) or Wide Area Networks (WAN) or a LAN and its ISP's network . for example, your PC or workgroup and EarthLink. Routers are located at gateways, the places where two or more networks connect. Using headers and forwarding tables, routers determine the best path for forwarding the packets. Router use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.
A router is typically connected to at least two networks, commonly two Local Area Networks (LANs) or Wide Area Networks (WAN) or a LAN and its ISP's network . for example, your PC or workgroup and EarthLink. Routers are located at gateways, the places where two or more networks connect. Using headers and forwarding tables, routers determine the best path for forwarding the packets. Router use protocols such as ICMP to communicate with each other and configure the best route between any two hosts.
Features of Integrated
Routers
Today,
a wide variety of services are integrated into most broadband routers. A router
will typically include a 4 - 8 port Ethernet switch (or hub) and a Network
Address Translator (NAT). In addition, they usually include a Dynamic Host
Configuration Protocol (DHCP) server, Domain Name Service (DNS) proxy server
and a hardware firewall to protect the LAN from malicious intrusion from the Internet.
All routers have a WAN Port that connects to a DSL or cable modem for broadband Internet service and the integrated switch allows users to easily create a LAN. This allows all the PCs on the LAN to have access to the Internet and Windows file and printer sharing services.
All routers have a WAN Port that connects to a DSL or cable modem for broadband Internet service and the integrated switch allows users to easily create a LAN. This allows all the PCs on the LAN to have access to the Internet and Windows file and printer sharing services.
Routers
might have a single WAN port and a single LAN port and are designed to connect
an existing LAN hub or switch to a WAN. Ethernet switches and hubs can be
connected to a router with multiple PC ports to expand a LAN. Depending on the
capabilities (kinds of available ports) of the router and the switches or hubs,
the connection between the router and switches/hubs may require either
straight-thru or crossover (null-modem) cables. Some routers even have USB ports, and more commonly, wireless access
points built into them.
Some of the more high-end or business class routers will also incorporate a serial port that can be connected to an external dial-up modem, which is useful as a backup in the event that the primary broadband connection goes down, as well as a built in LAN printer server and printer port.
Besides the inherent protection features provided by the NAT, many routers will also have a built-in, configurable, hardware-based firewall. Firewall capabilities can range from the very basic to quite sophisticated devices. Among the capabilities found on leading routers are those that permit configuring TCP/UDP ports for games, chat services, and the like, on the LAN behind the firewall.
So, in short, a hub glues together an Ethernet network segment, a switch can connect multiple Ethernet segments more efficiently and a router can do those functions plus route TCP/IP packets between multiple LANs and/or WANs; and much more of course.
Some of the more high-end or business class routers will also incorporate a serial port that can be connected to an external dial-up modem, which is useful as a backup in the event that the primary broadband connection goes down, as well as a built in LAN printer server and printer port.
Besides the inherent protection features provided by the NAT, many routers will also have a built-in, configurable, hardware-based firewall. Firewall capabilities can range from the very basic to quite sophisticated devices. Among the capabilities found on leading routers are those that permit configuring TCP/UDP ports for games, chat services, and the like, on the LAN behind the firewall.
So, in short, a hub glues together an Ethernet network segment, a switch can connect multiple Ethernet segments more efficiently and a router can do those functions plus route TCP/IP packets between multiple LANs and/or WANs; and much more of course.
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