Virtual Circuit A Virtual Circuit is a communication path between devices that is utilized only during the duration of a specific message transmission. Packet Switching vs. Circuit Switching Telephony measures capacity in terms of symmetrical two-way circuits between two points. Digital telecommunication measures one-way packet transmission capacity in terms of bits per second. Therefore, a telephony circuit is a datastream of 64 Kbps. IBM and Novel are two commercial companies that use proprietary standards.
Routers are devices that connect different networks using the same protocols.
In the paper, they showed how one could interlink the then incompatible, proprietary centralized computing system networks used at the time. This design allows different packets, all representing a single message, to take different routes through a network and being reconstructed at the destination. In theory, communications should be faster and robust, because packets can be automatically routed around nodes that are congested or have failed. The concepts of packet switching were incorporated into the ARPAnet military network that was the forerunner of the Internet. That Cerf and Kahn maintained that their methods should be freely available and not associated with any particular vendor is largely responsible for the current ubiquitous of the Internet.