On a Cisco router, when will the router actually reserve the bandwidth for the MPLS traffic
engineering tunnel?
A.
during the autoroute process
B.
during constraint-based routing calculations
C.
on the receipt of the RSVP Path message
D.
on the receipt of the RSVP Resv message
Explanation:
https://tools.ietf.org/html/rfc2210
The RSVP FLOWSPEC object carries reservation request (Receiver_TSpec and RSpec) information generated by data receivers. The information in the FLOWSPEC flows upstream towards data sources.
An application receiver wishing to make a resource reservation supplies its local RSVP with the necessary reservation parameters. Among these are the QoS control service desired (Guaranteed or Controlled-Load), the traffic specifier (TSpec) describing the level of traffic for which resources should be reserved, and, if needed by the selected QoS control service, an RSpec describing the level of service desired. These parameters are composed into an RSVP FLOWSPEC object and transmitted upstream by RSVP.
At each RSVP-aware point in the network, the SENDER_TSPECs arriving in PATH messages and the FLOWSPECs arriving in RESV messages are used to request an appropriate resource reservation from the desired QoS
control service.
See section: 3.2.1 FLOWSPEC object when requesting Controlled-Load service