Frame Relay point-to-point subinterfaces: When configuring point-to-point subinterfaces on a physical Frame Relay interface, which item must NOT be configured?

Introduction / Context:Point-to-point Frame Relay subinterfaces are a classic way to avoid split-horizon and simplify addressing in hub-and-spoke topologies. Correct placement of IP addressing and DLCIs is critical for proper operation.

Given Data / Assumptions:

• Physical interface carries Frame Relay encapsulation.
• Subinterfaces are defined as point-to-point.
• Each subinterface binds to a single DLCI and has its own IP network.

Concept / Approach:With Frame Relay subinterfaces, Layer 3 addressing belongs on the subinterface, not on the physical interface. The physical interface provides the Layer 2 service (Frame Relay encapsulation and LMI). Each point-to-point subinterface is treated like its own logical interface with a unique IP and a single DLCI mapping.

Step-by-Step Solution:

Verification / Alternative check:Show run should display IP addresses under subinterfaces (e.g., Serial0/0.1, Serial0/0.2) and none under the parent interface; LMI runs on the parent.

Why Other Options Are Wrong:Frame Relay encapsulation on the physical: Needed for the link-layer. Local DLCI on each subinterface: Required to identify the PVC. Subinterface type: Must be 'point-to-point' for p2p subinterfaces.

Common Pitfalls:Accidentally configuring an IP on the physical interface causes addressing conflicts and breaks subinterface design.

Final Answer:An IP address on the physical interface