PVC vs SVC

PVC and SVC are different types of virtual circuits. “PVC” stands for “Permanent Virtual Circuit” and “SVC” stands for “Switched Virtual Circuit.” Both PVC and SVC play the main role in networks like Frame Relay and X.25. They are also used in ATM machines. To understand their differences, let us first understand what Frame Relay and X.25 networks are.

Frame Relay Networks
Frame Relay network is a protocol for a data link network. These networks are specially designed for transferring data on WANs or wide area networks. Frame Relay works on ISDN lines or fiber optics; they offer low latency and corrects errors thus reducing the overhead. The protocol provides cost-effective telecommunication which has been adopted by companies to transfer long-distance data. In recent times, the popularity of relay networks is diminishing due to the gradual migration towards IP or Internet Protocol based solutions.

X.25
X.25 network is also a WAN or wide area network protocol. It was adopted by the telecommunication companies and is a standard protocol of CCITT or Consultative Committee for International Telegraph and Telephone. This protocol allows computers to communicate via intermediate computer networks even when the computers are on various different public networks.

PVC (Permanent Virtual Circuit)
PVC is a virtual circuit which is available permanently. It is a type of virtual circuit where the end points do not signal the circuit. The virtual circuit values are manual. The route through the network, link-by-link is also manual. If the equipment happens to fail, the PVC also fails, and the physical network has to re-route. The permanent virtual circuit is an efficient circuit for hosts which have to communicate frequently like ATMs.

SVC (Switched Virtual Circuit)
SVC has to re-establish the connection every time the data has to be sent. It is a circuit established by UNI. It is basically a demand connection; the connection is initiated by the user. When the switch fails, the SVC fails, and the connection needs to be re-established.

Summary:

1.“PVC” is a virtual circuit which is available permanently. It is a type of virtual circuit where the end points do not signal the circuit. The virtual circuit values are manual. However, “SVC” is a circuit which is an on-demand circuit established by the user signals.
2.“PVC” is a permanent circuit while “SVC” must be re-established every time when there is a need for a data transfer. 3.The SVC disappears as soon as the data is transferred.

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