The very first step in your OCI journey would be setting up a VCN(Virtual Cloud Network) in oracle cloud infrastructure.
So lets be familiar with all networking components.
1. VCN ( Virtual Cloud Network)
It is almost similar to the on-premise network we have with firewall rules and communication gateways. VCN resides in a single OCI region. A region can have multiple availability domain. VCN is created with contiguous block of IPV4 addresses of your choice and once created , changes can not be done in the range of it.
Allowable VCN size is /16 and /30 . So it is important to think about size of VCN and subnets before creating them.
2. Subnet :
As we already knew , Subnets are designed to divide larger network into smaller , efficient network. So , in OCI you can logically divide your VCN’s network into sub networks.
Each subnet consists of single contiguous range of IP addresses which do not overlap with other subnet’s IP addresses within VCN. We can create a subnet either in the single availability domain or across the region.
3. VNIC (Virtual Network Interface Card) :
It is a network interface card which attached to a instance and resides in the specific subnet. Each instance has primary VNIC card which determines how that instance can communicate inside and outside of VCN.
The primary VNIC which is attached to the instance while creation can not be removed in the instance’s life-time. However, you can always add secondary VNIC to your instance.
Each VNIC has a private IP address from the subnet the VNIC is in. Optionally you can assign upto 31 secondary IP addresses.
4. Private IP address :
Instance needs IP address to communicate and each instance has one privare IP address assigned to it through VNIC. VNIC has one primary IP address assigned to it which can not be changed in the life time of an instance. You can optionally add and remove secondary IP addresses.
5. Public IP Address :
You can optionally assign public IP address to you instance or other resources which has private IP assigned. The public IP could be ephemeral (temporary) or reserved.
6. Dynamic Routing Gateway :
It is an optional virtual router which creates communication roadmap between your VCN and on-premise network. You can access on-premise network either through VPN connect or OCI Fastconnect.
VPN connect offers multiple IPSec tunnels between your existing network of your data center and VCN. With DRG you can attach it to your VCN.
FastConnect offers private connection between OCI and your existing network’s edge. Traffic does not traverse the internet.
These are the basic networking components we use in Oracle Cloud Infrastructure. There are some advance networking components like NAT gateway , service gateway , local and remote peering etc.
We will discuss those in next posts.
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