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Zorluk: OrtaSeparation of Control Plane and Data Plane

In network architectures, router and switch operations are divided between distinct functional planes. Which of the following network functions are executed directly by the data (forwarding) plane? (Select TWO.)

  1. Decrementing the IP Time to Live (TTL) field and updating the header checksum for transit packetsCevap
  2. Matching incoming packet headers against the Forwarding Information Base (FIB) in TCAM hardwareCevap
  3. C
    Exchanging OSPF Link-State Advertisements (LSAs) to build the Routing Information Base (RIB)
  4. D
    Processing incoming Cisco Discovery Protocol (CDP) and LLDP neighbor management frames
  5. E
    Authenticating administrative SSH access requests using TACACS+ or RADIUS servers

Cevap

The data plane is responsible for decrementing the IP TTL field (and updating the checksum) for transit packets and performing destination address lookups against the Forwarding Information Base (FIB) using specialized hardware ASICs and TCAM.
The data plane (also known as the forwarding plane) handles user traffic passing through the network device. It operates at line rate using specialized hardware such as Application-Specific Integrated Circuits (ASICs) and Ternary Content-Addressable Memory (TCAM). Standard data plane duties include looking up destination addresses in the Forwarding Information Base (FIB), rewriting Ethernet MAC addresses, decrementing the IPv4 Time to Live (TTL) or IPv6 Hop Limit, and updating header checksums. In contrast, dynamic routing protocols (OSPF/BGP) and Layer 2 discovery mechanisms (CDP/LLDP) reside in the control plane, while administrative access protocols (SSH, TACACS+, RADIUS) belong to the management plane.

Adım Adım Çözüm

1
Differentiate plane responsibilities
Control plane creates routing rules and topology information (RIB, OSPF, CDP); data plane forwards customer transit traffic at line rate based on pre-computed hardware tables (FIB, TCAM). Management plane handles device access.
Clear separation of duties ensures high-speed forwarding without overloading the central CPU.
2
Evaluate packet header modification and FIB lookup
Decrementing TTL, recalculating checksums, frame rewriting, and TCAM FIB matching occur per-packet in hardware, placing them in the data plane.
These actions must occur on every single packet passing through the switch or router.
3
Identify non-data plane functions
OSPF LSA processing and CDP/LLDP messaging belong to the control plane, while TACACS+/SSH access belongs to the management plane.
Control plane protocols update internal topology tables, whereas management plane services handle administrative oversight.

Anahtar Kavram

Data Plane Responsibilities vs. Control/Management Planes
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Konular

Separation of Control Plane and Data Plane

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