Router
Contents
Router
A router is a networking device that forwards data packets between computer networks. Routers perform the traffic directing functions on the Internet. Data sent over the internet, such as a web page or email, is in the form of data packets. A router inspects a packet's destination IP address, determines the best path to forward it, and then sends it on its way.
History
The concept of a router originated from the earlier "interface message processors" (IMPs) in the ARPANET. The first true IP router was developed by Virginia Strazisar at BBN Technologies in 1975-1976. Commercial routers began to emerge in the early 1980s, and their importance grew with the expansion of the Internet.
Key Features
Routers are equipped with several key features that enable their function:
- Multiple Network Interfaces: Routers have multiple physical ports (e.g., Ethernet, Wi-Fi) to connect to different networks.
- Routing Table: A database that stores information about network paths and their associated metrics (e.g., cost, speed) to determine the best route for data packets.
- Routing Protocols: Algorithms (e.g., OSPF, BGP, RIP) used by routers to exchange routing information with other routers and dynamically update their routing tables.
- Packet Forwarding: The core function of moving data packets from an incoming interface to an outgoing interface based on the routing table.
- Network Address Translation (NAT): Often used in home and small office routers to allow multiple devices on a private network to share a single public IP address.
- Firewall Capabilities: Many routers include basic firewall features to filter incoming and outgoing traffic, enhancing network security.
- Quality of Service (QoS): Allows prioritization of certain types of network traffic (e.g., voice or video) over others to ensure better performance.
- DHCP Server: Automatically assigns IP addresses to devices connecting to the network.
Types of Routers
Routers come in various forms, each designed for specific environments:
- Wireless Routers: Combine the functions of a router, a wireless access point, and often a network switch. Commonly used in homes and small offices.
- Broadband Routers (DSL/Cable Routers): Integrate a modem with routing capabilities to connect directly to an Internet Service Provider (ISP).
- Core Routers: High-capacity routers used in the backbone of the Internet or large enterprise networks, designed for speed and reliability.
- Edge Routers: Connect an enterprise network to an external network (e.g., the Internet) and often handle security and QoS.
- Virtual Routers: Software-based routers that run on servers or cloud platforms, offering flexibility and scalability.
How it Works
When a data packet arrives at a router, the router performs the following steps:
- Inspects Destination IP: It reads the destination IP address contained in the packet's header.
- Consults Routing Table: It compares the destination IP address with entries in its routing table to find the best path to the destination network.
- Determines Next Hop: Based on the routing table, it identifies the next router or device in the path.
- Forwards Packet: The packet is then sent out through the appropriate outgoing interface towards the next hop.
If no specific route is found, the packet might be sent to a default gateway or dropped if no path is available.
Use Cases
Routers are fundamental to modern networking and are used in:
- Home Networks: Connecting multiple devices (computers, smartphones, smart TVs) to the internet and to each other.
- Small Office/Home Office (SOHO): Providing internet connectivity and local network services.
- Enterprise Networks: Segmenting large corporate networks, connecting different departments, and providing secure access to external networks.
- Internet Service Providers (ISPs): Building the infrastructure of the Internet, directing traffic across vast distances.
- Data Centers: Managing traffic flow between servers and storage devices.
Advantages
- Network Interconnectivity: Enables communication between different types of networks.
- Traffic Management: Efficiently directs data packets to their destinations, preventing network congestion.
- Security: Many routers include firewall and security features to protect networks.
- Scalability: Allows for the expansion of networks by connecting new segments.
- Reliability: Can often find alternative paths if a primary path fails.
Disadvantages
- Configuration Complexity: Advanced configurations can be challenging for inexperienced users.
- Security Vulnerabilities: If not properly secured, routers can be targets for cyberattacks.
- Single Point of Failure: A malfunctioning router can disrupt an entire network, though redundancy measures can mitigate this.
