In a Juniper Networks environment, deploying RSVP-signaled LSPs requires a functional Traffic Engineering Database (TED). This database is populated by the Interior Gateway Protocol (IGP) using specific extensions that carry link-state information beyond simple reachability, such as available bandwidth, administrative groups (link coloring), and Maximum Reservable Bandwidth.

The behavior of these extensions differs between OSPF and IS-IS in Junos OS:

OSPF (Option C): By default, OSPF is a 'pure' routing protocol. To support RSVP-TE, it must carry Opaque LSAs (Type 10). According to Juniper documentation, you must explicitly configure traffic engineering within the OSPF protocol hierarchy using the set protocols ospf traffic-engineering command. Without this command, OSPF will not flood the TE information required by the Constrained Shortest Path First (CSPF) algorithm, and LSPs will fail to establish.

IS-IS (Option D): IS-IS was designed to be extensible through the use of TLVs (Type, Length, Value). In Junos OS, IS-IS traffic engineering extensions are enabled by default once the protocol is active. As soon as you enable IS-IS on an interface, it begins to advertise the wide metrics and TE TLVs (like TLV 22 and 135) necessary for building the TED.

This distinction is a common design consideration for network architects. While IS-IS simplifies the rollout of MPLS by having TE enabled 'out of the box,' OSPF requires that extra configuration step to transition from a standard IGP to a TE-aware protocol.