How does router help information to reach to the destination on the Internet?

Wired routers usually connect directly to modems or wide-area networks (WANs) via network cables. They typically come with a port that connects to modems to communicate with the Internet.

Wireless routers

Routers can also connect wirelessly to devices that support the same wireless standards. Wireless routers can receive information from and send information to the Internet.

How routers route data

Routing, defined

Routing is the ability to forward IP packets—a package of data with an Internet protocol (IP) address—from one network to another. The router's job is to connect the networks in your business and manage traffic within these networks. Routers typically have at least two network interface cards, or NICs, that allow the router to connect to other networks.

Speeding data across networks

Routers figure out the fastest data path between devices connected on a network, and then send data along these paths. To do this, routers use what's called a "metric value," or preference number. If a router has the choice of two routes to the same location, it will choose the path with the lowest metric. The metrics are stored in a routing table.

Creating a routing table

A routing table, which is stored on your router, is a list of all possible paths in your network. When routers receive IP packets that need to be forwarded somewhere else in the network, the router looks at the packet's destination IP address and then searches for the routing information in the routing table.

If you are managing a network, you need to become familiar with routing tables since they'll help you troubleshoot networking issues. For example, if you understand the structure and lookup process of routing tables, you should be able to diagnose any routing table issue, regardless of your level of familiarity with a particular routing protocol.

As an example, you might notice that the routing table has all the routes you expect to see, yet packet forwarding is not working as well as expected. By knowing how to look up a packet's destination IP address, you can determine if the packet is being forwarded, why the packet is being sent elsewhere, or whether the packet has been discarded.

Managing routers

When you need to make changes to your network's routing options, you log in to your router to access its software. For example, you can log in to the router to change login passwords, encrypt the network, create port forwarding rules, or update the router's firmware.

How routers can help your business

Routers help give employees access to business applications and therefore improve productivity—especially for employees who work remotely or outside main offices. Routers can also enable specialized services such as VoIP, video conferencing, and Wi-Fi networks.

Speeding access to information

With routers in place, your business can improve responses to customers and enable easier access to customer information. These are real benefits at a time when customers demand fast answers to questions, as well as personalized service. By using routers to build a fast and reliable small business network, employees are better able to respond rapidly and intelligently to customer needs.

Reducing operating costs

Routers can have a positive impact on your bottom line. Your small business can save money by sharing equipment such as printers and servers, as well as services such as Internet access. A fast and reliable network built with routers can also grow with your business, so you don't have to keep rebuilding the network and buying new devices as the business expands.

Improving security

Routers can help you protect valuable business data from attacks if they offer built-in firewalls or web filtering, which examines incoming data and blocks it as needed.

Enabling secured remote connections

Routers help your business provide secure remote access for mobile workers who need to communicate with other employees or use business applications. This is a common scenario for many businesses that have virtual teams and home-based telecommuters who need to share critical business information at any time of the day or night.

Creating small business networks with routers

Invest in business-grade switches and routers

Consumer or home networking products won't keep pace with the challenges of business growth.

Build networks that can grow over time

This way, you can add features and functionality when needed, such as video surveillance, VoIP, integrated messaging, and wireless applications.

Choose routers designed with reliability and redundancy

This provides the business continuity you'll need to bounce back quickly from unforeseen and disruptive events, like natural disasters.

A router is an operates at the network layer of the OSI reference model. Routers are used to connect two or more IP networks.

A router consists of a computer with at least two network interface cards supporting the IP protocol. The router receives packets from each interface via a network interface and forwards the received packets to an appropriate output network interface. The key points here are that routers in the network have a perspective of the correct path to use to reach a destination.

A router receives packets from each interface via a network interface. Received packets have all link protocol headers removed.

The router uses the information in the IP header to decide whether and where to forward each received packet, and which network interface to use to send the packet. Most packets are forwarded based on the packet's IP destination address, along with routing information held within the router in a routing table.

A router does not by default forward a packet with an IP broadcast address. Protocols using broadcast packets normally only operate within a single broadcast domain. (Routers can sometimes be specifically configured to support this.)

Once the transmit interface is selected, the router checks the Maximum Transfer Unit (MTU) of the interface. If the packet size is less than or equal to the MTU, the processing continues. All IP packets contain a TTL value that determines the number of router hops that a packet may be routed, this is decremented by most routers (although routers can be configured to reduce the value by more than 1) It is used to prevent routing loops, and ensures topologies with loops do not result in packets that circulate indefinitely.

At the output interface, the packet (together with a new link layer header) is placed into a transmit queue until the link layer processor is ready to transmit the packet. This, like the receive queue. Each out-going packet requires a new link layer protocol header to be added (encapsulation) with the destination address set to the next system to the receive the packet. The link protocol controller also maintains the hardware address table associated with the interface. This usually involves using the Address ReResit Exam Solution Protocol (arp) to find out the hardware (MAC) addresses of other computers or routers directly connected to the same cable (or LAN). The packet is finally sent using the media interface with the hardware address set to the next hop system. In this way, transmitted packets have a new link protocol header added prior to transmission of each packet.

IPv4 Packets larger than the interface MTU cannot be sent. They can be fragmented by the router into two or more smaller packets. If an IPv4 packet is received which has the Don't Fragment (DF) bit set in the packet header or uses IPv6, the packet is not fragmented, but is instead discarded. In this case, an ICMP error message is returned to the sender (i.e. to the original packet's IP source address) informing it of the interface's MTU size. This forms the basis for Path MTU discovery (PMTU).

Routing and Filter Tables

The routing and filter tables resemble similar tables in link layer bridges and switches. Except, that instead of specifying link hardware addresses (MAC addresses), the router table sepcify network (IP addresses). The routing table lists known IP destination addresses with the appropraite network interface to be used to reach that destiantion. A default entry may be specified to be used for all addresses not explicitly defined in the table (this is very common in routers close to the edge of the networ, where the default routes packets towards the Internet backbone).

A filter table may also be used to ensure that unwanted packets are discarded. The filter may be used to deny access to particular protocols or to prevent unauthorised access from remote computers by discarding packets to a specified destination address. Routers at the edge of ISP networks also often perform filtering of the IP source address, as a way to prevent "spoofing" of addresses belonging to other networks.

A router forwards packets from one IP network to another IP network. Like other systems, it routes based on the longest-prefxi match of the IP addresss in the routing table.

One exception to this rule is when a router receives an IP packet to a network broadcast address. In this case, the router will process the packet internally (to see if it needs to respond) and then discards the packet. Forwarding a broadcast packet can lead to severe storms of packets, and if uncontrolled could lead to network overload.

Latency

A router introduces delay (latency) as it processes the packets it receives. The total delay observed is the sum of many components including:

Time taken to process the frame by the data link protocol
Time taken to select the correct output link (i.e. filtering and routing)
Queuing delay at the output link (when the link is busy)
Other activities which consume processor resources (computing routing tables, network management, generation of logging information)

The router queue of packets waiting to be sent also introduces a potential cause of packet loss. Since the router has a finite amount of buffer memory to hold the queue, a router which receives packets at too high a rate may experience a full queue. In this case, the router ahs no other option than to simply discard excess packets. If required, these may later be retransmitted by a transport protocol.

Architecture of a router

Routers are often used to connect together networks which use different types of links. The optimum (and maximum) packet lengths (i.e. the maximum transmission unit (MTU)) is different for different types of network. A router may therefore uses IP to provide segmentation of packets into a suitable size for transmission on a network.

IP routers allow alternate paths to be dynamically selected when routers forward packets. Adding parallel paths through the network adds robustness to failure - if one link, interface (or router) fails, an alternate path may be selected restoring end-to-end connectivity. All IP packets contain a TTL value that determines the number of router hops that a packet may be routed. A router decrements the hop count (IPv4 TTL or IPv6 HopCount) field each time it forwards a packet. If a packet gets stuck in a loop the TTL counts down to zero - at which point the packet is automatically discarded.

Associated protocols perform network error reporting (ICMP), communication between routers (to determine appropriate routes to each destination) and remote monitoring of the router operation (network management).

What is a router How does it help information to reach to the destination on the internet?

A router is a device that connects two or more packet-switched networks or subnetworks. It serves two primary functions: managing traffic between these networks by forwarding data packets to their intended IP addresses, and allowing multiple devices to use the same Internet connection.

How does router know destination?

The router replies with its MAC address, and the device uses this as the destination address for the Ethernet frame in which it has encapsulated the IP packet. Thus the IP packet arrives at the local router, which routes it to the internet.

How does a router communicate with the internet?

A wireless router connects directly to a modem by a cable. This allows it to receive information from — and transmit information to — the internet. The router then creates and communicates with your home Wi-Fi network using built- in antennas. This provides all the devices on your home network with internet access.

How does a router route traffic?

Each router builds a routing table that lists all possible routes to all possible destinations. Based on that routing table, a router selects what it thinks is the best path to the packet's destination – usually it is the shortest path, unless a policy is in place to pick a different one.