350-401 · Question #790
How do the RIB and the FIB differ?
The correct answer is D. RIB is derived from the control plane, and the FIB is derived from the RIB.. The Routing Information Base (RIB) is derived from the control plane and contains all learned routes, while the Forwarding Information Base (FIB) is derived from the RIB for optimized packet forwarding.
Question
How do the RIB and the FIB differ?
Options
- AFIB contains routes learned through a dynamic routing protocol, and the RIB contains routes that
- BRIB contains the interface for a destination, and the FIB contains the next hop information.
- CFIB is derived from the control plane, and the RIB is derived from the data plane.
- DRIB is derived from the control plane, and the FIB is derived from the RIB.
How the community answered
(32 responses)- B3% (1)
- C3% (1)
- D94% (30)
Why each option
The Routing Information Base (RIB) is derived from the control plane and contains all learned routes, while the Forwarding Information Base (FIB) is derived from the RIB for optimized packet forwarding.
Both the RIB and FIB contain routes, but the FIB is specifically built for fast forwarding based on the best paths in the RIB.
Both RIB and FIB contain information to determine the next hop and outgoing interface, but the FIB's role is specifically to optimize this for data plane forwarding.
The RIB is indeed derived from the control plane, but the FIB is derived from the RIB, which itself is a control plane construct, before being used by the data plane for actual forwarding.
The Routing Information Base (RIB) is populated by control plane protocols and configurations, holding all learned routes and their associated metrics. The Forwarding Information Base (FIB) is then derived directly from the RIB, containing the optimized information needed for high-speed packet forwarding decisions on the data plane.
Concept tested: Routing Information Base (RIB) vs. Forwarding Information Base (FIB)
Source: https://www.cisco.com/c/en/us/support/docs/ip/express-forwarding/16181-cef.html
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