300-320 · Question #44
To which network layer should Cisco Express Forwarding be tuned to support load balancing and to make more informed forwarding decisions?
The correct answer is D. Layer 4. By default, CEF performs load balancing using Layer 3 information (source and destination IP addresses). Tuning CEF to use Layer 4 information (source and destination TCP/UDP port numbers) allows it to distinguish between multiple flows between the same two hosts and distribute…
Question
To which network layer should Cisco Express Forwarding be tuned to support load balancing and to make more informed forwarding decisions?
Options
- ALayer 1
- BLayer 2
- CLayer 3
- DLayer 4
- ELayer 5
- FLayer 6
- GLayer 7
How the community answered
(27 responses)- A7% (2)
- B15% (4)
- C4% (1)
- D74% (20)
Explanation
By default, CEF performs load balancing using Layer 3 information (source and destination IP addresses). Tuning CEF to use Layer 4 information (source and destination TCP/UDP port numbers) allows it to distinguish between multiple flows between the same two hosts and distribute them across different paths, resulting in more granular and effective load balancing. This is especially useful when multiple applications run between the same endpoints, as Layer 3-only hashing would send all their traffic down a single path.
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