In tear-down phase of a circuit-switched network, a signal is sent to release…
2021
In tear-down phase of a circuit-switched network, a signal is sent to release the resources —
Answer: B. to each switch — ConceptA circuit-switched network reserves a dedicated end-to-end path before data transfer. Each switching node on that path stores local connection state…
- A.
to each router
- B.
to each switch
- C.
to each computer
- D.
to each server
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Correct answer: B
Concept
A circuit-switched network reserves a dedicated end-to-end path before data transfer. Each switching node on that path stores local connection state and commits a channel or capacity to that circuit.
Teardown reverses setup: the network must notify every switching node that holds part of the reservation so that each node can remove its cross-connect state and return the capacity to the free pool.
Application
The established circuit passes through a sequence of circuit switches between the two end systems.
Each such switch holds local state and reserved capacity for this circuit.
A release signal therefore propagates along the established path and is processed by each switch, which frees its local reservation.
Contrast and cross-check
A router primarily forwards individual packets using routing and forwarding tables rather than holding the circuit cross-connect described here.
A computer or server is an end system; it is not the repeated intermediate resource holder along the circuit path.
If even one circuit switch were not notified, its reserved channel would remain occupied, so complete release requires notifying each switch.
Therefore, the release signal is sent to each switch on the established circuit path.