Need ordering but still want packet efficiency — can we reserve a logical path without reserving bandwidth like circuit?
Per Wikipedia: “A virtual circuit network sets up a logical path before data, packets carry VCI and follow same path, combining setup with packet switching.”
Like booking a train seat but not the whole train — you have reserved route but share tracks.
- Signal setup reserves VCI along path
- Packets tag VCI not full address
- Routers forward via VCI table
- Packets arrive in order
- Teardown releases VCIs
- Ordered delivery
- Per-flow state in routers
- Setup latency
- Fails if intermediate router reboots
MPLS labels are VCIs- Built from: Circuit Switching — borrows setup idea
- Built from: Packet Switching — borrows packet sharing
- Contrasts with: Datagram Network — VC is connection-oriented
- Related: Store-and-Forward — VCs also store-forward
- Confusing with circuit — VC shares bandwidth
- VCI reuse after teardown collides if stale