Without perfectly understanding the difference between access point and router, one cannot understand the importance they have to each other. An access point is a device to which Wi-Fi devices connect to. An access point alone would not be much useful as it only connects Wi-Fi devices together. In order to connect the devices to a wired network, to provide internet, the access point must be connected to a router. The router will take packets coming from the access point and forward them necessarily to the wired network to provide internet access to the Wi-Fi devices. So, in summary, an access point connects the Wi-Fi devices to the router and the connected router routes the packets appropriately to enable useful communication.
What is an Access Point?
An access point is a device used to connect wireless devices to a wired network. Such devices are widely used in Wi-Fi technology. The device called the access point creates a hotspot that broadcast an SSID. Other Wi-Fi enabled devices such as laptops, mobile phones,and tablets connect to this hotspot using the Wi-Fi. The access point is generally connected to a router. Devices connected to the access point will be provided with internet through the router to which the access point is connected to. Also, all devices connected to the aces point will be interconnected with the local area network as well as, to enjoy various other services such as file sharing. It is important to not that in modern wireless routers the router and the access point is integrated into one single device.
Imagine a situation at home where we have an ADSL internet connection and a home network. The wired ADSL router connects to the telephone line at one side and in the other side several computers are connected to the router via Ethernet cables. This creates a LAN and all devices can communicate with each other and can access internet. Now, say we buy an access point and connect it using an Ethernet cable to the ADSL router. The access point will create a Wi-Fi hotspot and any Wi-Fi device at home can connect to the access point and they can access internet because the packets are routed via ADSL. Apart from that wireless devices can communicate among them and also can communicate with the wired LAN.
Modern Wi-Fi cards found on laptops and mobile phones also can act as access points. Software such as connectify me, Virtual Router, and also built-in tools in operating systems let you share internet by turning the Wi-Fi module on your laptop or mobile phone into a virtual access point.
What is a Router?
A router is a networking device that routes data packets across a network. It works in the network layer of the OSI reference model, and hence, is a layer 3 device. A router maintains a table called a routing table, which consists of the gateway IP through which a packet must be routed to reach a certain destination IP. The routing table can be statically set by the network administrator or can be auto-generated using routing algorithms. When a router receives a packet, it first stores the packet in the router memory and analyzes the destination IP address of the packet. Then it lookup the routing table to see through which gateway the packet must be routed. Then based on that information it forwards the packet appropriately.
An access point definitely needs a router to connect its wireless devices to the internet. Access point only integrates the Wi-Fi devices together, but it does not know how to route packets outside. So, it must be connected to a router and now the router will forward the packets coming from the access point necessarily to the outside network. Today, there are Wi-Fi routers in the market that integrates the functionality of the Wi-Fi access point and the router into a single device. Even ADSL Wi-Fi routers are there which integrates Wi-Fi access point, router and the ADSL connectivity.
What is the difference between Access Point and Router?
• An access point lets Wi-Fi devices to connect to it. The router connects the access point to the outside network such as internet.
• An access point does not have the capability to route packets while the router does this to route packets to the proper destination.
• A router has a switching fabric that routes packets from different input interfaces to correct output interfaces. An access point only directs what is coming from the Wi-Fi receiver to the wired interface and what is coming from the wired interface to the Wi-Fi transmitter.
• Routers run complex algorithms called routing algorithms and involve data structures called the routing table. Such complex algorithms and routing tables are not found on access points.
• An access point has wireless hardware like Wi-Fi receivers and transmitters while a router does not have this hardware.
Summary:
Access Point vs Router
The access point is the devices to which the Wi-Fi devices connect. The access point is connected to the router and the router routes the packets from the access point to the outside network to provide internet access. The access point has the wireless hardware where it broadcasts an SSID to which other Wi-Fi devices connect to. The router does not have wireless hardware, but consist of switching fabric, memory and processing devices to store and forward packets appropriately to reach the correct destination. Today, the devices called Wi-Fi routers have the functionality of the access point and the router combined into one single package.
Images Courtesy: Wireless router via Wikicommons (Public Domain)