Netowrking in OCI:

TCP

Definition: Connection-oriented, reliable protocol that guarantees ordered delivery of data packets with error-checking, requiring three-way handshake (SYN, SYN-ACK, ACK) before communication in OCI networks.

UDP

Definition: Connectionless, stateless protocol that sends data packets without establishing connection or guarantee of delivery, prioritizing speed over reliability in OCI communications.

Trust Network (Trusted Network)

Definition: Internal, secured network segment within OCI Virtual Cloud Network (VCN) where traffic between resources is pre-authorized and allowed by default based on security group rules.

Untrust Network (Untrusted Network)

Definition: External, potentially unsafe network (typically public internet) from which traffic enters OCI infrastructure and requires explicit authentication and authorization through firewall rules.

Firewall

Definition: OCI security layer consisting of Security Groups (stateful) and Network Security Groups (NSGs) that controls inbound/outbound traffic between resources by filtering packets based on protocol, port, and source/destination IP.

Route (Routing Rule)

Definition: Forwarding rule in OCI Route Table that determines path for network packets by matching destination IP address/CIDR block and directing traffic to appropriate target (gateway, instance, or service).

Gateway

Definition: OCI network component that serves as entry/exit point for traffic between VCN and external networks, including Internet Gateway (public internet access), NAT Gateway (outbound NAT), Service Gateway (private OCI service access), and VPN Gateway (encrypted site-to-site connection).

Gateway Types in OCI Internet Gateway: Opens VCN to public internet for bidirectional communication with external systems.

NAT Gateway: Allows instances in private subnet to initiate outbound internet connections while hiding private IPs.

Service Gateway: Provides private, direct path to OCI services without traversing public internet.

VPN Gateway: Encrypts traffic between on-premises network and OCI VCN through IPSec tunnel.

Protocols

Definition: Standardized communication rules in OCI networking that define format, timing, sequencing, and error-checking for data transmission between network entities, including TCP, UDP, ICMP, HTTP/HTTPS, SSH, DNS, and others.

Summary: