You are managing a Site-to-Site VPN connection between your on-premises network and OCI. You notice that the VPN tunnel is frequently dropping and…

Symptoms: VPN tunnel drops intermittently despite stable internet and IKE settings.

VPN Components: Requires IKE (UDP 500/4500) and ESP (IP 50) traffic.

Evaluate Options:

A: Incorrect CPE IP would prevent tunnel establishment, not intermittent drops; incorrect.

B: DRG outage would cause full downtime, not intermittent; unlikely.

C: Security rules blocking IKE/ESP intermittently (e.g., rate limiting) is common; most likely.

D: NAT-Traversal issues typically prevent initial setup, not intermittent drops; less likely.

Conclusion: Security rule misconfiguration is the most probable cause.

VPN stability depends on unblocked IKE and ESP traffic. The Oracle Networking Professional study

guide notes, "Intermittent VPN tunnel drops are often caused by security rules or firewalls blocking

IKE (UDP 500/4500) or ESP (IP Protocol 50) traffic" (OCI Networking Documentation, Section: Site-to-

Site VPN Troubleshooting). This aligns with the scenario’s symptoms.

Reference: Oracle Cloud Infrastructure Documentation - Site-to-Site VPN.