So where do we start? Well a network router is a more sophisticated network device compared to a network switch. Like switches, routers are typically small, box-like pieces of equipment that multiple computers can connect to. Each features a number of ports on the front or back of the unit that provide the connection points for these computers or devices, a connection for electric power, and a number of LED lights to display computer/device status. While routers and switches all share similar physical appearance, routers differ substantially in their inner workings.
A traditional router is designed to join together multiple local area networks (LANs) with a wide area network (WAN). Routers serve as intermediate destinations for network traffic. They receive incoming network packets, look inside each packet to identify the source and target network addresses, then forward these packets where needed to ensure the data reaches its final destination.
Routers for home networks (often called broadband routers) are designed specifically to join the home (LAN) to the Internet (WAN) for the purpose of Internet connection sharing. In contrast, switches are not capable of joining multiple networks or sharing an Internet connection. A network with only switches must instead designate one computer as the gateway to the Internet, and that device must possess two network adapters for sharing, one for the home LAN and one for the Internet WAN. With a router, all home computers connect to the router as peers, and the router performs all gateway functions.
Additionally, broadband routers contain several features beyond those of traditional routers such as integrated DHCP server and network firewall support. Most notably, though, broadband routers typically incorporate a built-in Ethernet switch. This allows several switches to be connected to them, as a means to expand the local network to accommodate more Ethernet devices.
Wi-Fi wireless networks also utilize routers but technically do not have the concept of a wireless switch, although a wireless access point can be roughly compared to a wired switch.
Routers are small physical devices that join multiple networks together. Technically, a router is a Layer 3 gateway device, meaning that it connects two or more networks and that the router operates at the network layer of the OSI model.
Home networks typically use a wireless or wired Internet Protocol (IP) router, IP being the most common OSI network layer protocol. An IP router such as a DSL or cable modem broadband router joins the home’s local area network (LAN) to the wide-area network (WAN) of the Internet.
By maintaining configuration information in a piece of storage called the routing table, wired or wireless routers also have the ability to filter traffic, either incoming or outgoing, based on the IP addresses of senders and receivers. Some routers allow a network administrator to update the routing table from a Web browser interface. Broadband routers combine the functions of a router with those of a network switch and a firewall in a single unit.
A network switch is a small hardware device that joins multiple computers together within one local area network (LAN). Ethernet switch devices were commonly used on home networks before home routers became popular; broadband routers integrate Ethernet switches directly into the unit as one of their many functions. High-performance network switches are still widely used in corporate networks and data centers.
Network Switch Technology
While switching capabilities exist for several types of networks, Ethernet switches are the most common type. Mainstream Ethernet switches like those inside broadband routers support Gigabit Ethernet (1 Gbps) speeds, but high-performance switches like those in data centers generally support 10 Gbps.
Different models of network switches support differing numbers of connected devices. Consumer-grade network switches provide either four or eight connections for Ethernet devices, while corporate switches typically support between 32 and 128 connections. Switches can additionally be connected to each other, a so-called daisy chaining method to add progressively larger number of devices to a LAN.
Network switches operate at layer two (Data Link Layer) of the OSI model.
In computer networking, the term port can refer to either physical or virtual connection points.
Physical network ports allow connecting cables to computers, routers, modems and other peripheral devices. Several different types of physical ports available on computer network hardware include:
Virtual ports are part of TCP/IP networking. These ports allow software applications to share hardware resources without interfering with each other. Computers and routers automatically manage network traffic traveling via their virtual ports. Network firewalls additionally provide some control over the flow of traffic on each virtual port for security purposes.
A packet is one unit of binary data capable of being routed through a computer network. To improve communication performance and reliability, each message sent between two network devices is often subdivided into packets by the underlying hardware and software. Depending on the protocol(s) they need to support, packets are constructed in some standard packet format. Packet formats generally include a header, the body containing the message data (also known as the payload), and sometimes a footer (also known as the trailer). The packet header lists the destination of the packet (in IP packets, the destination IP address) and often indicates the length of the message data. The packet footer contains data that signifies the end of the packet, such as a special sequence of bits known as a magic number. Both the packet header and footer may contain error-checking information.
The receiving device is responsible for re-assembling individual packets into the original message, by stripping off the headers and footers and concatenating packets in the correct sequence.
DHCP (Dynamic Host Configuration Protocol) allows a computer to join an IP-based network without having a pre-configured IP address. DHCP is a protocol that assigns unique IP addresses to devices, then releases and renews these addresses as devices leave and re-join the network.
Internet service providers usually use DHCP to help customers join their networks with minimum setup effort required. Likewise, home network equipment like broadband routers offers DHCP support for added convenience in joining home computers to local area networks (LANs).
DHCP environments require a DHCP server set up with the appropriate configuration parameters for the given network. Key DHCP parameters include the range or “pool” of available IP addresses, the correct subnet masks, plus network gateway and name server addresses.
Devices running DHCP client software can then automatically retrieve these settings from DHCP servers as needed. DHCP clients are built into all common network operating systems. Using DHCP on a network means system administrators do not need to configure these parameters individually for each client device.