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Datagram vs virtual circuit switching
Short answer
Packet switching includes datagram and virtual circuit. Datagram is connectionless: each packet carries full destination address, routed independently, may arrive out of order. Virtual circuit uses a pre-established path, carries a short VC identifier, delivers packets in order, and provides easier QoS.
What is data switching? Clarify the differences between datagram switching and virtual circuit packet switching.
Data switching
Switching is the process of transferring data from a source to a destination through a series of intermediate nodes, so that every pair of devices need not be directly connected. The main types are circuit, message and packet switching.
Packet switching has two forms: datagram and virtual circuit.
- Datagram: each packet (datagram) is treated independently and carries the full destination address; routers choose the route for each packet. No call setup.
- Virtual circuit: a logical path is set up first by a call-request, all packets then carry a short VC number and follow that path in order, and the path is cleared at the end.
Datagram: P1 -> R1 -> R2 -> B
P2 -> R1 -> R3 -> B (different paths)
VC : setup A..R1..R2..B ; all packets use this path
| Point | Datagram | Virtual circuit |
|---|---|---|
| Connection | Connectionless | Connection-oriented |
| Setup phase | None | Required (call setup and clear) |
| Header | Full destination address | Short VC identifier |
| Routing | Decision for every packet | Once, at setup |
| Order of delivery | May be out of order | In order |
| Reliability | Reordering and error control by end hosts | Can be provided by the network (e.g. X.25) |
| Failure of a node | Packets re-routed, little loss | All circuits through it fail |
| Resource reservation | None | Possible, QoS easier |
| Congestion | Handled per packet, harder to control | Easier to control |
| Examples | IP (Internet) | X.25, frame relay, ATM |
✓ Answer checked by Claude Sonnet 5.5
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