Routers, hardware to support the internet

“Describe the role of the PSTN (Public Switched Telephone Network) in transmission of data through the internet”

• PSTN consists of many different types of communication lines

  • Therefore digital data may need to be converted into a different form/analogue signal

• Data is transmitted in both directions at the same time - Full duplex

• Using a PSTN the communication passes through different switching centres/ISPs

“Modem use in transmitting video conference over the internet”

• Converts digital data into analogue for transmission down phone lines

• Converts analogue data into digital after transmission down phone lines

“Dedicated lines use in transmitting video conference over the internet”

• Used to provide a direct/private connection which therefore provides faster transmission

“Describe the role of routers in the transmission of data through the internet”

• Receives packets from the internet

• ANalyses the destination IP address of each packet

• Forwards the packet towards its destination

  • Using the routing table

• Maintains/updates the routing table

• Finds the most efficient route to the destination

“Describe the function of a router in a network - connecting LAN to internet”

• Receives packets from internet/external network

• Implements a firewall

• ANalyses the destination IP address of each packet

• Forwards the packet towards its destination 

  • Using routing table

• Maintains the routing

• Allocates private IP addresses

• Finds the most efficient route to the destination

• Changes the packet format for transmission over the next network

• Network Address Translation; technique used by routers to allow multiple devices in a private local area network (LAN) to share a single public IP address