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.

Advantage of Router 

a) Router limits the collision domain.
b) Router can function on LAN & WAN
c) Router can connects different media & architectures.
d) Router can determine best path/route for data to reach 
the destination.
e) Router can filter the broadcasts

Disadvantage of Router -

a) Router is more expensive than Hub, Bridge & Switch. 
b) Router only work with routerable protocol.
c) Routing updates consume bandwidth.
d) Increase latency due to greater degree of packet 
filtering 

 

The Advantages of Using a Router for Your Computer

Routers allow multiple computers to connect to the Internet.

A router is type of computer networking hardware that is able to receive incoming data packets and send--or rout--them to different devices. Many home users have external modems plugged directly into their computer's Ethernet adapter in order to connect to the Internet; using a router in your network configuration can have many advantages over other simple setups.

  

Security

• When you use a router to set up a network, your live Internet connection is plugged into the router instead of being plugged directly into a computer's Ethernet adapter. This forces data to pass through the router before it is sent out to computers on the network. Many routers contain hardware firewalls that allow them to filter and block potentially harmful data. This can keep threats like computer viruses and other malware from affecting the computers on your network. Even if you use a software firewall program, a router's firewall can provide an additional level of protection.

LAN

• Routers allow users to set up local area networks (LANs) that can allow several computers to access the Internet through a single Internet connection. Routers typically have four or more Ethernet ports that computers can connect to in addition to a port to accept an incoming Internet connection from a modem. This means that by using a router you can connect four or more devices to the Internet even if you only have one modem. The number of computers you connect to your LAN can be further expanded by connecting other networking devices to the router. For instance, you can connect a network hub to the router to create more ports for computers to connect to.

Wireless Connectivity

• One of the most important advantages of using routers is the potential for wireless connectivity. While some routers are designed purely for wired connections using Ethernet cables, wireless routers allow computers to network with wires and RF signals. Any computer that has a wireless adapter card that is close enough to the router to pick up a signal can connect to it and access the Internet and other resources on the network. This is beneficial for networks in public places as it allows people to connect without having to locate the router and connect cables. Using a wireless router does, however, come with the drawback of piggybackers: people attempting to connect to your router without your permission. To prevent unwanted connections it is important to set up wireless security measures and a network password.
  
  
  

  Types of Router

  Routers  provide connectivity inside enterprises, between enterprises and the Internet, and within an Internet Service Provider ( ISP ).One of the largest routers  e.g. the Cisco CRS-1 or Juniper T1600 interconnects internet Service Providers (ISPs), they are used within ISPs, or may be used in very large enterprise networks. The smallest routers provide connectivity for small and home offices.

   

  
  

  Edge Router 

  
  

  
  

  This type of router are placed at the edge of the ISP network, the are normally configured to external protocol like BGP (Border gateway protocol) to another BGP of other ISP or large organisation. 

  
  

  
  

  Subscriber Edge Router

  
  

  
  

   This type of router belongs to  an end user (enterprise) organization. It’s configured to  broadcast External BGP to it’s provider’s AS(s).

  
  

  
  

  Inter-provider Border Router

  
  

  
  

  This type of router is  for Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes. 

  
  

  
  

  Core Router

  
  

  
  

   A router that resides within the middle or backbone of the LAN network rather than at its periphery. In some instances , a core router provides a stepdown backbone , interconnecting the distribution routers from multiple building of a campus ( LAN), or Large enterprise Location (WAN). They tend to be optimized for a high brandwidth.

  
  

  
  

  Wired and Wireless Routers. 

  
  

  
  

  Home and small office networking is becoming popular by day by the use of IP wired and wireless router.Wired and wireless router are able to maintain routing and configuration information in their routing table.  They also provide the service of filtering traffic of incoming and outgoing packets based on IP addresses.Some wireless routers combines the functions of router with those of a network switch and that of a firewall in one.

  
  
  
  Uses Of Routers
  
  The router uses the information held in the network layer header (i.e. IP header) to decide whether 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. Before a packet is forwarded, the processor checks the Maximum Transfer Unit (MTU) of the specified interface. Packets larger than the interface's MTU must be fragmented by the router into two or more smaller packets. If a packet is received which has the Don't Fragment (DF) bit set in the packet header, the packet is not fragmented, but 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).

   

   

   How To Set Up Router

   

  This guide explains how to set up a router for home computer networks. The exact names of configuration settings on a network router vary depending on the model and whether it is wired or wireless. However, this general procedure will guide you through the process for the common kinds of home network equipment.

   

  Difficulty: Average

  Time Required: 1 hour

  Here's How:

  1. Choose a convenient location to begin installing your router such as an open floor space or table. This does not need to be the permanent location of the device. Particularly for wireless routers, you may find it necessary to re-position the unit after installing it as the cables / signals may not reach all areas needed. At the beginning, its better to choose a location where it's easiest to work with the router and worry about final placement later.
     
  2. Plug in the router's electrical power source, then turn on the router by pushing the power button.
     
  3. (Optional) Connect your Internet modem to the router. Most network modems connect via an Ethernet cable but USB connections are becoming increasingly common. The cable plugs into the router jack named "WAN" or "uplink" or "Internet." After connecting the cable, be sure to power cycle (turn off and turn back on) the modem to ensure the router recognizes it.
     
  4. Connect one computer to the router. Even if the router is a wireless model, connect this first computer to the router via a network cable. Using a cable during router installation ensures the maximum reliability of the equipment. Once a wireless router installation is complete, the computer can be changed over to a wireless connection if desired.
     
  5. Open the router's administration tool. From the computer connected to the router, first open your Web browser. Then enter the router's address for network administration in the Web address field and hit return to reach the router's home page.
     
     Many routers are reached by either the Web address "http://192.168.1.1" or "http://192.168.0.1" Consult your router's documentation to determine the exact address for your model. Note that you do not need a working Internet connection for this step.
     
  6. Log in to the router. The router's home page will ask you for a username and password. Both are provided in the router's documentation. You should change the router's password for security reasons, but do this after the installation is complete to avoid unnecessary complications during the basic setup.
     
  7. If you want your router to connect to the Internet, you must enter Internet connection information into that section of the router's configuration (exact location varies). If using DSL Internet, you may need to enter the PPPoE username and password. Likewise, if you have been issued a static IP address by your provider (you would need to have requested it), the static IP fields (including network mask and gateway) given to you by the provider must also must be set in the router.

   

  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)