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Zorluk: OrtaRouting Concepts and Dynamic Routing Protocols

A network administrator is analyzing packet captures on a core router interface to troubleshoot routing updates. The administrator observes routing protocol packets being encapsulated directly into Layer 3 IP payloads using IP protocol number 89, without using Layer 4 Transport Layer headers such as TCP or UDP. Which of the following dynamic routing protocols is generating these packet captures?

  1. Open Shortest Path First (OSPF)Cevap
  2. B
    Border Gateway Protocol (BGP)
  3. C
    Routing Information Protocol (RIPv2)
  4. D
    Enhanced Interior Gateway Routing Protocol (EIGRP) over TCP

Cevap

Open Shortest Path First (OSPF) is the dynamic routing protocol that encapsulates its protocol messages directly into Layer 3 IP payloads using IP protocol number 89.
Open Shortest Path First (OSPF) formats its protocol messages directly inside IP packets using IP protocol number 89. It does not use Layer 4 protocols like TCP or UDP, managing packet delivery reliability internally through link-state acknowledgments.

Adım Adım Çözüm

1
Identify the OSI layer encapsulation characteristics described in the scenario.
The routing protocol operates directly above Layer 3 (IP) with IP protocol number 89 and does not use a Layer 4 transport protocol (TCP or UDP).
Different dynamic routing protocols operate at different layers of the network protocol stack.
2
Evaluate the protocol encapsulation mechanisms of the listed dynamic routing protocols.
OSPF uses IP protocol number 89 directly over IP, BGP uses TCP port 179, and RIPv2 uses UDP port 520.
Knowing protocol numbers and transport mechanisms helps distinguish protocol behaviors during packet analysis.
3
Select the matching routing protocol.
Open Shortest Path First (OSPF) matches IP protocol number 89 direct IP encapsulation.
OSPF implements its own reliable transport mechanism via link-state acknowledgments rather than relying on TCP or UDP.

Anahtar Kavram

Dynamic Routing Protocol Encapsulation and Layer 3 Operations
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Konular

Routing Concepts and Dynamic Routing Protocols

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