VSC ‐ minimum number of CIDR IPS needed in HUB VCN - SanjeevOCI/Study GitHub Wiki
SanjeevOCI: what is minimum number of CIDR IPS needed in HUB VCN compared to Spoke VCN
GitHub Copilot: In a hub-and-spoke network architecture, the minimum number of CIDR IPs needed in the Hub VCN compared to the Spoke VCN depends on the specific requirements and design of your network. However, here are some general guidelines:
-
Hub VCN:
- The Hub VCN typically requires more CIDR IPs because it needs to accommodate:
- Subnets for different services (e.g., VPN, NAT, Load Balancers).
- Subnets for routing traffic between Spoke VCNs.
- Any additional services or resources that are centralized in the Hub.
- The Hub VCN typically requires more CIDR IPs because it needs to accommodate:
-
Spoke VCN:
- Each Spoke VCN usually requires fewer CIDR IPs because it primarily needs to accommodate:
- Subnets for the specific applications or services hosted in the Spoke.
- Subnets for internal communication within the Spoke.
- Each Spoke VCN usually requires fewer CIDR IPs because it primarily needs to accommodate:
Example
- Hub VCN: You might allocate a larger CIDR block, such as
10.0.0.0/16, which provides 65,536 IP addresses. - Spoke VCN: Each Spoke VCN might use a smaller CIDR block, such as
10.1.0.0/24, which provides 256 IP addresses.
Considerations
- Routing: Ensure that the CIDR blocks do not overlap and that routing tables are properly configured to allow communication between the Hub and Spokes.
- Scalability: Plan for future growth by allocating larger CIDR blocks if you anticipate adding more subnets or services.
- Security: Use network security groups (NSGs) and route tables to control traffic flow between the Hub and Spokes.
Ultimately, the exact number of CIDR IPs needed will depend on the specific requirements of your network architecture and the services you plan to deploy.
SanjeevOCI: Spoke VCN CIDR - 10.1.0.0/25..break into 3 subnets....web subnet - 32 IPs, app subnet - 64 IPs, DB Subnet - 32 IPs
GitHub Copilot: To break the Spoke VCN CIDR 10.1.0.0/25 into three subnets with the specified IP requirements, you can use the following subnets:
- Web Subnet: 32 IPs
- App Subnet: 64 IPs
- DB Subnet: 32 IPs
Here is how you can allocate the subnets:
- Web Subnet:
10.1.0.0/27(32 IPs) - App Subnet:
10.1.0.32/26(64 IPs) - DB Subnet:
10.1.0.96/27(32 IPs)
Subnet Breakdown
-
Web Subnet:
10.1.0.0/27- Network Address:
10.1.0.0 - Usable IP Range:
10.1.0.1to10.1.0.30 - Broadcast Address:
10.1.0.31
- Network Address:
-
App Subnet:
10.1.0.32/26- Network Address:
10.1.0.32 - Usable IP Range:
10.1.0.33to10.1.0.94 - Broadcast Address:
10.1.0.95
- Network Address:
-
DB Subnet:
10.1.0.96/27- Network Address:
10.1.0.96 - Usable IP Range:
10.1.0.97to10.1.0.126 - Broadcast Address:
10.1.0.127
- Network Address:
Summary
- Web Subnet:
10.1.0.0/27(32 IPs) - App Subnet:
10.1.0.32/26(64 IPs) - DB Subnet:
10.1.0.96/27(32 IPs)
This allocation ensures that you have the required number of IPs for each subnet while fitting within the 10.1.0.0/25 CIDR block.
SanjeevOCI: HUB VNET - 172.16.0.0/27 - 32 IPs, split 8 IPS each for hub_vnet_pubic_subnet and Gateway Subnet. Keep 16 Ips vacant for future use
GitHub Copilot: To split the 172.16.0.0/27 CIDR block into subnets with 8 IPs each for hub_vnet_public_subnet and Gateway Subnet, and keep 16 IPs vacant for future use, you can allocate the subnets as follows:
- hub_vnet_public_subnet: 8 IPs
- Gateway Subnet: 8 IPs
- Vacant Subnet: 16 IPs (reserved for future use)
Subnet Breakdown
-
hub_vnet_public_subnet:
172.16.0.0/29- Network Address:
172.16.0.0 - Usable IP Range:
172.16.0.1to172.16.0.6 - Broadcast Address:
172.16.0.7
- Network Address:
-
Gateway Subnet:
172.16.0.8/29- Network Address:
172.16.0.8 - Usable IP Range:
172.16.0.9to172.16.0.14 - Broadcast Address:
172.16.0.15
- Network Address:
-
Vacant Subnet:
172.16.0.16/28- Network Address:
172.16.0.16 - Usable IP Range:
172.16.0.17to172.16.0.30 - Broadcast Address:
172.16.0.31
- Network Address:
Summary
- hub_vnet_public_subnet:
172.16.0.0/29(8 IPs) - Gateway Subnet:
172.16.0.8/29(8 IPs) - Vacant Subnet:
172.16.0.16/28(16 IPs, reserved for future use)
This allocation ensures that you have the required number of IPs for each subnet while keeping 16 IPs vacant for future use within the 172.16.0.0/27 CIDR block.
SanjeevOCI: HUB VNET - 172.16.0.0/24...distribute IPS as mentioned below
hub_vnet_public_subnet: 16 IPs
Gateway Subnet: 16 IPS
For later use - remaining IPS
GitHub Copilot: To distribute the IPs within the 172.16.0.0/24 CIDR block as specified, you can allocate the subnets as follows:
- hub_vnet_public_subnet: 16 IPs
- Gateway Subnet: 16 IPs
- Remaining IPs: For later use
Subnet Breakdown
-
hub_vnet_public_subnet:
172.16.0.0/28- Network Address:
172.16.0.0 - Usable IP Range:
172.16.0.1to172.16.0.14 - Broadcast Address:
172.16.0.15
- Network Address:
-
Gateway Subnet:
172.16.0.16/28- Network Address:
172.16.0.16 - Usable IP Range:
172.16.0.17to172.16.0.30 - Broadcast Address:
172.16.0.31
- Network Address:
-
Remaining Subnet:
172.16.0.32/27(or larger, depending on future needs)- Network Address:
172.16.0.32 - Usable IP Range:
172.16.0.33to172.16.0.62 - Broadcast Address:
172.16.0.63
- Network Address:
Summary
- hub_vnet_public_subnet:
172.16.0.0/28(16 IPs) - Gateway Subnet:
172.16.0.16/28(16 IPs) - Remaining Subnet:
172.16.0.32/27(or larger, depending on future needs)
This allocation ensures that you have the required number of IPs for each subnet while keeping the remaining IPs available for future use within the 172.16.0.0/24 CIDR block.
SanjeevOCI: terraform init ╵ [sanjeev_sa@57fcede9c528 OCI]$ terraform init
Initializing the backend...
Initializing provider plugins...
- Reusing previous version of hashicorp/oci from the dependency lock file ╷ │ Error: Failed to query available provider packages │ │ Could not retrieve the list of available versions for provider hashicorp/oci: the previously-selected version 6.21.0 is no longer available
VS Code:
SanjeevOCI: Getting below error after running "terraform init" command in OCI Cloud EDitor
Error: Failed to query available provider packages
Could not retrieve the list of available versions for provider hashicorp/oci: the previously-selected version 6.21.0 is no longer available
VS Code: It seems like the version 6.21.0 of the provider hashicorp/oci is no longer available. You can try updating the provider version in your Terraform configuration file.
Open your main.tf or equivalent Terraform configuration file and update the provider version to a currently available version.