- 2070 Asar · 4 marks
Virtual circuit switching
Short answer
Virtual circuit switching sets up a logical path before data transfer, with packets following the same path using a VCI. It combines circuit and packet switching, gives in-order delivery and small headers, but has setup delay and fails if a switch fails. Examples: X.25, Frame Relay, ATM.
Explain virtual circuit switching.
Virtual circuit (VC) switching is a packet-switching technique that combines features of circuit and packet switching. A logical path (virtual circuit) is set up between source and destination before data is sent, and all packets of the session follow this same path in order. The resources are not reserved exclusively, so bandwidth is still shared.
Phases
- Connection setup: a request packet travels to the destination; each switch chooses an outgoing link and records a VCI (virtual circuit identifier) in its table.
- Data transfer: every packet carries only a short VCI, not the full destination address. Switches use the VCI to forward and may change it on each link.
- Teardown: the connection is closed and table entries are removed.
A --VCI 5--> [S1] --VCI 9--> [S2] --VCI 3--> B
Features
- Packets arrive in order; no reordering.
- Smaller header, fast forwarding after setup.
- Drawbacks: there is a setup delay, and the circuit fails if a switch on the path fails.
- Examples: X.25, Frame Relay, ATM.
It differs from datagram switching, where each packet is routed independently by full address.
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Circuit vs packet switching · Computer Networks and Security, chapter 2 · asked 3×
- Datagram vs virtual circuit switching · Data Communication, chapter 7 · asked 3×
- Datagram vs virtual circuit switching · Telecommunications, chapter 8
- Short note: Virtual-circuit network · Telecommunications, chapter 8 · asked 2×
- Virtual short circuit and inverting integrator · Basic Electronics Engineering, chapter 4