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A VCN is a customizable private network in Oracle Cloud Infrastructure. Just like a traditional data center network, a VCN provides you with complete control over your network environment. This includes assigning your own private IP address space, creating subnets, creating route tables, and configuring stateful firewalls. A single tenancy (an Oracle Cloud Infrastructure account) can have multiple VCNs, thereby providing grouping and isolation of related resources. For example, you might use multiple VCNs to separate the resources in different departments in your company.
For a complete list of components, see Overview of Networking.
When you create your VCN, you assign a contiguous IPv4 CIDR block of your choice. VCN sizes ranging from /16 (65,533 IP addresses) to /30 (1 IP address) are allowed. Example: 10.0.0.0/16, 192.168.0.0/24.
We recommend using a CIDR block from the private address ranges specified by RFC1918. If you use a non-RFC1918 CIDR block, note that it is still treated as a private IP address range and is not routable from the internet (via Oracle's internet gateway).
You create subnets by subdividing the VCN's address range into contiguous IPv4 CIDR blocks. A subnet's CIDR block must fall within the VCN's CIDR block. When you launch an instance into a subnet, the instance's private IP address is allocated from the subnet's CIDR block.
Yes. When you create a subnet, you can specify the access type: either private or public. A subnet is created with public access by default, in which case the instances in the subnet can be allocated a public IP address. Instances launched in a subnet with private access are prohibited from having public IP addresses, which ensures these instances have no direct internet access.
Subnets can span multiple availability domains, but not multiple VCNs. If you create a regional subnet, the subnet's resources can reside in any availability domain in the region. However, if you create an AD-specific subnet, the subnet's resources must reside in the subnet's particular availability domain.
Yes. However, if you intend to connect a VCN to your on-premises network or another VCN, we recommend you ensure that the IP address ranges don’t overlap.
For current limits for all services and instructions for requesting a service limit increase, see the Service Limits help documentation.
Yes, you can modify the subnet's name and change which route table, security lists, and set of DHCP options are associated with it. However, you cannot change the subnet's CIDR block.
The servers in Oracle Cloud Infrastructure data centers have physical network interface cards (NICs). When you launch an instance on one of these servers, the instance communicates using the Networking service's virtual NICs (VNICs) associated with the physical NICs. A VNIC enables a compute instance to be connected to a VCN and determines how the instance communicates with endpoints inside and outside the VCN.
Each VNIC resides in a subnet and has the following configuration:
For more information, see Virtual Network Interface Cards (VNICs).
Every instance in your VCN is created with a VNIC, which has a private IP address (assigned by you or Oracle) from the subnet provided at instance creation, and a corresponding public IP address. This VNIC is referred to as the primary VNIC, and its private IP address as the primary private IP address.
The primary VNIC cannot be detached from the instance. It gets automatically deleted when the instance is terminated.
Every instance in your VCN has at least one VNIC, which is its primary VNIC. You can attach additional VNICs to an instance, which are referred to as secondary VNICs. The secondary VNICs can belong to different VCNs or subnets.
The limit to how many VNICs can be attached to an instance varies by shape. For those limits, see Compute Shapes support documentation.
Yes. Query the instance metadata service available at http://169.254.169.254/opc/v1/vnics/.
Yes. In case of the primary VNIC, you can specify the private IP address at instance launch. In case of secondary VNICs, you can specify a private IP address when you attach the VNIC to an instance. The specified private IP address should belong to the same subnet the VNIC belongs to, and should not be in use.
No. Currently, VNICs are always bound to the instance and do not exist independently. The primary VNIC is created and destroyed with the instance. All secondary VNICs are created and destroyed when they are attached and detached respectively.
Yes. However, attaching multiple VNICs from the same subnet CIDR block to an instance can introduce asymmetric routing, especially on instances using a variant of Linux. If you need this type of configuration, Oracle recommends assigning multiple private IP addresses to one VNIC, or using policy based-routing. For an example, see the script in the Linux: Configuring the OS for Secondary VNICs.
No. All VNICs must belong to subnets in the same AD as the instance. When using regional subnets, the VNICs must be created in the same AD as the instance.
Yes. You can attach secondary VNICs that belong to a subnet of a VCN that is different from the VCN of the primary VNIC.
Every compute instance in your VCN is created with a virtual network interface card (VNIC) and is assigned a private IP address from the subnet provided at instance launch. These are the primary VNIC and its primary private IP address, respectively. You can also attach additional VNICs to an instance, referred to as secondary VNICs, which also have a primary private IP address.
You can let Oracle choose the private IP address, or you can choose it from the subnet's available pool. If the address you specify is already in use, the launch request will fail.
Additionally, you can assign secondary private IP addresses to a VNIC. Similar to primary private IP addresses, a secondary private IP address provides connectivity to destinations within your VCN and/or on-premises (when there is connectivity through VPN or FastConnect).
Yes. You can move a secondary private IP address from a VNIC on one instance to a VNIC on another instance, provided that both VNICs belong to the same subnet and authorization allows the operation. When using regional subnets, the secondary private IP can be moved to a VNIC in a different AD as well.
Currently you can assign up to 31 secondary private IP addresses to a VNIC.
No. The OS cannot discover the secondary private IP address using mechanisms like DHCP. You need to configure the secondary private IP addresses using an OS-specific procedure. For more information, see the scripts provided in Virtual Network Interface Cards (VNICs).
A public IP address is an IPv4 address that is reachable from the internet (an internet-routable IP address). An instance in your VCN communicates with hosts on the internet via a public IP address. A private IP address is not internet routable. Instances inside the VCN communicate with each other using private IP addresses.
You can assign a public IP address to a private IP address of a compute instance, or to a load balancer instance, and enable them to communicate with the internet. For a public IP address to be reachable over the internet, the VCN it's in must have an internet gateway, and the public subnet must have route tables and security lists configured accordingly.
There are two types of public IP addresses.
For more details and a table comparing the two types, see Public IP Addresses help documentation.
A public IP address becomes the identity of your service for clients that cannot use the DNS FQDN. A reserved public IP address allows you to keep this identity regardless of any changes to the underlying resources. Here are a couple of specific scenarios that can benefit from using a reserved public IP address:
You can assign only one reserved public IP address to any (primary or secondary) private IP address. However, you can assign multiple private IP addresses to each VNIC attached to your instance. You can then assign a reserved public IP address to each of these private IP addresses.
There is a limit on the maximum number of reserved public IP addresses you can create in your tenancy. See the Service Limits help documentation.
You can assign only one ephemeral public IP address to any primary private IP address of the VNIC. However, you can create and attach multiple VNICs to your instance. You can then assign an Ephemeral private IP address to each of the primary IP address of each VNIC.
There is a limit on the maximum number of ephemeral public IP addresses that can be assigned to an instance. See the Service Limits help documentation.
Yes, but only if it's assigned to a secondary private IP on a VNIC. If you move that secondary private IP to a different VNIC (which must be in the same subnet), the ephemeral public IP goes with it.
Yes, and you can move it from one availability domain or VCN to another. The VCNs must be in the same region.
There are two ways to move a reserved public IP:
When you explicitly unassign it. Also:
Note that when you reboot the instance, there is no impact to the corresponding ephemeral public IP addresses.
You see only the private IP address of your compute instance. If the instance is assigned a public IP address, the Networking service provides a one-to-one NAT (static NAT) between the private and public IP addresses when the instance tries to communicate to a destination on the internet (through the internet gateway).
At the instance OS level, you see only the private IP address of the VNIC attached to the instance. When traffic sent to the public IP address is received, the Networking service does a network address translation (NAT) from the public IP address to the corresponding private IP address. The traffic shows up inside your instance with the destination IP address set to the private IP address.
No. The Networking service assigns the MAC address.
IPv6 addressing is currently supported only in the Government Cloud. For more information, see IPv6 Addresses.
No, not currently.
No, not currently.
The instances can connect:
An internet gateway is a software-defined, highly available, fault-tolerant router providing public internet connectivity for resources inside your VCN. Using an internet gateway, a compute instance with a public IP address assigned to it can communicate with hosts and services on the internet.
In lieu of using an internet gateway, you can connect your VCN to your on-premises data center, from which you can route traffic to the internet via your existing network egress points.
A NAT gateway is a reliable and highly available router that provides outbound-only internet connectivity for resources inside your VCN. With a NAT gateway, private instances (with only a private IP address) can initiate connections to hosts and services on the internet, but not receive inbound connections initiated from the internet.
No. The default limit is one NAT gateway per VCN. We expect this to be sufficient for the vast majority of applications.
If you would like to allocate more than one NAT gateway in a specific VCN, request a limit increase. For instructions on how to request an increase in limits, see Service Limits.
Instances get the same throughput with the NAT gateway as they do when the traffic is routed through an internet gateway. In addition, a single traffic flow through the NAT gateway is limited to 1Gbps (or less for small instance shapes).
Yes, there is a limit of ~20,000 concurrent connections to a single destination IP address and port. This limit is aggregate of all connections initiated by instances across the VCN that are using the NAT gateway.
A dynamic routing gateway is a software-defined, highly available, fault-tolerant router that you can add to a VCN. It provides a private path for traffic between the VCN and other networks outside the VCN's region, such as your an on-premises data center or a peered VCN in another region. To connect your VCN with your on-premises data center, you can set up an IPSec VPN or FastConnect to the VCN's DRG. The connection enables your on-premises hosts and instances to communicate securely.
You use this object if you set up an IPSec VPN. It's a virtual representation of the actual router that is on-premises at your site, at your end of the VPN. When you create this object as part of setting up an IPSec VPN, you specify the public IP address of your on-premises router.
No. You just need to provision a DRG, attach it to your VCN, configure the CPE object and IPSec connection, and configure the route tables.
Yes, if you configure it according to Generic CPE Configuration Information. We support multiple configuration options to maximize interoperability with different VPN devices.
Oracle provisions two VPN tunnels as part of the IPSec connection. Make sure to configure both tunnels on your CPE for redundancy.
Additionally, you can deploy two CPEs routers in your on-premises data center, with each configured for both tunnels.
IPSec VPN is an open standard and software IPSec VPNs can interoperate with Oracle Cloud Infrastructure. You need to verify that your software IPSec VPN supports at least one supported Oracle IPSec parameter in each configuration group according to Generic CPE Configuration Information.
The Oracle Services Network is a conceptual network in Oracle Cloud Infrastructure that is reserved for Oracle services. The network comprises a list of regional CIDR blocks. Every service in the Oracle Services Network exposes a service endpoint that uses public IP addresses from the network. A large number of Oracle services are currently available in this network (see the complete list), and more services will be added in the future as they get deployed on Oracle Cloud Infrastructure.
A service gateway lets resources in your VCN privately and securely access Oracle services in the Oracle Services Network, such as Object Storage, ADW, and ATP. Traffic between an instance in the VCN and a supported Oracle service uses the instance's private IP address for routing, travels over the Oracle Cloud Infrastructure fabric, and never traverses the internet. Much like the internet gateway or NAT gateway, the service gateway is a virtual device that is highly available and dynamically scales to support the network bandwidth of your VCN.
Currently, you can configure the service gateway to access Oracle services in the Oracle Services Network. A large number of Oracle services are currently available in this network (see the complete list), and more services will be added in the future as they get deployed on Oracle Cloud Infrastructure.
For instructions, see the Access to Object Storage: Service Gateway. Please note that the service gateway allows access to Oracle services within the region to protect your data from the internet. Your applications may require access to public endpoints or services not supported by the service gateway (for example, for updates or patches). Ensure you have a NAT gateway or other access to the internet if necessary.
The service gateway uses the concept of a service CIDR label, which is a string that represents all the regional public IP address ranges for the service or a group of services (for example, "OCI IAD Services in Oracle Services Network" is the label that maps to the regional CIDR blocks in the Oracle Services Network in us-ashburn-1). You use the service CIDR label when you configure the service gateway and route/security rules. For instructions, see the Access to Oracle Services: Service Gateway.
No, the service gateway is regional and can access only services running in the same region.
Yes. If you're using a service gateway, you can define an IAM policy that allows access to a bucket only if the requests come from a specific VCN or CIDR range. The IAM policy works only for traffic routed through the service gateway. Access is blocked if the IAM policy is in place and the traffic instead goes through an internet gateway. Also, be aware that the IAM policy prevents you from accessing the bucket through the Console. Access is allowed only programmatically from resources in the VCN.
For an example IAM policy, see the Access to Object Storage: Service Gateway.
No. A VCN can have only one service gateway at this time.
No. A VCN that is peered with another VCN that has a service gateway cannot use that service gateway to access Oracle services.
No. However, you can use FastConnect public peering to do this (without going through internet).
No. Instances get the same throughput with the service gateway as they do when the traffic is routed through an internet gateway.
The service gateway is free for all Oracle Cloud Infrastructure customers.
A security list provides a virtual firewall for an instance, with ingress and egress rules that specify the types of traffic allowed in and out of the instance. You can secure your compute instance by using security lists. You configure your security lists at the subnet level, which means all the instances in the subnet are subject to the same set of security list rules. The rules are enforced at the instance level and control traffic at the packet level.
A given VNIC on an instance is subject to the security lists associated with the VNIC's subnet. When you create a subnet, you specify one or more security lists to associate with it, and that can include the VCN's default security list. If you don't specify at least one security list during subnet creation, the VCN's default security list is associated with the subnet. The security lists are associated at the subnet level, but the rules apply to the VNIC's traffic at the packet level.
Yes, you can edit subnet properties to add or remove security lists. You can also edit the individual rules in a security list.
There's a limit to the number of security lists you can create, the number of lists you can associate with a subnet, and the number of rules you can add to a given list. For current service limits and instructions on how to request an increase in limits, see the Service Limits help documentation.
No. Security lists use only "allow" rules. All traffic is denied by default and only network traffic matching the attributes specified in the rules is permitted.
Each rule is either stateful or stateless, and either an ingress rule or an egress rule.
With stateful rules, once a network packet matching the rule is allowed, connection tracking is used and all further network packets belonging to this connection are automatically allowed. So if you create a stateful ingress rule, both incoming traffic matching the rule and the corresponding outgoing (response) traffic are allowed.
With stateless rules, only the network packets matching the rule are allowed. So, if you create a stateless ingress rule, only the incoming traffic is allowed. You need to create a corresponding stateless egress rule to match the corresponding outgoing (response) traffic.
For more information, see the Security Lists support documentation.
Network security groups and security lists are two different ways to implement security rules, which are rules that control allowed ingress and egress traffic to and from VNICs.
Security lists let you defined a set of security rules that apply to all the VNICs in a given subnet. Network security groups (NSGs) let you define a set of security rules that apply to a group of VNICs of your choice (for example: a group of Compute instances that have the same security posture).
For more information, see:
No. By default, all traffic is denied. Security rules only allow traffic. The set of rules that applies to a given VNIC is the union of these items:
Compute, Load Balancing, and Database services. This means that when you create a Compute instance, a load balancer, or a DB system, you can specify one or more network security groups to control traffic for those resources.
With the introduction of NSGs, there's no change to security list behavior. Your VCN still has a default security list that you may optionally use with your VCN's subnets.
When writing rules for an NSG, you have the option to specify an NSG as the source of traffic (for ingress rules) or the traffic's destination (for egress rules). The ability to specify an NSG means that you can easily write rules to control traffic between two different NSGs. The NSGs must be in the same VCN.
No. When you write an NSG security rule that specifies another NSG as the source or destination, that NSG must be in the same VCN. This is true even if the other NSG is in a peered VCN.'s different from security list?
Security lists let you define a set of security rules that apply to all the VNICs in an entire subnet while Network security groups (NSGs) let you define a set of security rules that apply to a group of VNICs of your choice (including the vnic's of load balancers or DB systems) within a VCN.
A VCN route table contains rules to route traffic that's ultimately destined for locations outside the VCN.
Each rule in a route table has a destination CIDR block and a route target. When the subnet's outgoing traffic matches the destination CIDR block of the route rule, traffic is routed to the route target. Examples of common route targets: an internet gateway, a dynamic routing gateway.
For more information, see Route Tables.
A given VNIC on an instance is subject to the route table associated with the VNIC's subnet. When you create a subnet, you specify one route table to associate with it, and that can be the VCN's default route table or another you've already created. If you don't specify a route table during subnet creation, the VCN's default route table is associated with the subnet. The route table is associated at the subnet level, but the rules apply to the VNIC's traffic at the packet level.
No. Currently, you can add a route rule only for a CIDR block that doesn't overlap with the VCN's address space.
Yes, you can edit subnet properties to change the route table. You can also edit the individual rules in a route table.
No, not currently.
There's a limit to the number of rules in a route table. See the Service Limits help documentation.
Yes. You can use a private IP as the target of a route rule in situations where you want to route a subnet's traffic to another instance in the same VCN. For requirements and other details, see Using a Private IP as a Route Target.
VCN peering is a process of connecting two VCNs to enable private connectivity and traffic flow between them. There are two general types of peering:
For more information, see Access to Other VCNs: Peering.
For instructions, see Local VCN Peering.
No. The two VCNs in a local peering relationship cannot have overlapping CIDRs.
Yes. If VCN-1 is peered with two other VCNs (say VCN-2 and VCN-3), those two VCNs (VCN-2 and VCN-3) can have overlapping CIDRs.
A given VCN can have a maximum of ten local peerings at a time.
No. You establish a remote peering connection using a dynamic routing gateway (DRG).
For instructions, see Remote VCN Peering.
No. The two VCNs in a remote peering relationship cannot have overlapping CIDRs.
No, if VCN-1 is remotely peered with two other VCNs (say VCN-2 and VCN-3), those two VCNs (VCN-2 and VCN-3) cannot have overlapping CIDRs.
Yes. Your remote VCN peering traffic is encrypted using industry standard link encryption.
A given VCN can have a maximum of ten remote peerings at a time.
Yes. You can use VCN-A's route tables and security lists to control connectivity to the peered VCN-B. You can allow connectivity to the full address range of VCN-B, or limit it to one or more subnets.
Yes. After the local or remote peering is established, the instances in VCN-B can send traffic to the full address range of VCN-A. However, you can limit access from instances in VCN-B to a specific subnet in VCN-A by using appropriate ingress rules in the subnet's security lists.
No. Throughput and latency should be close to intra-VCN connections. Traffic over the local peering has similar availability and bandwidth constraints as the traffic between instances in a VCN.
Remote VCN peering uses the Oracle Cloud Infrastructure inter-region backbone, which is designed to deliver superior performance and availability characteristics, and a 99.5% availability SLA for inter-region connectivity. Traffic over the remote peering has similar availability and bandwidth constraints as any other connection to a dynamic routing gateway. You can achieve redundancy by backhauling the peering traffic using your FastConnect or IPSec VPN.
The VCN Transit Routing (VTR) solution is based on a hub-and-spoke topology and enables the hub VCN to provide transit connectivity between multiple spoke VCNs (within the region) and on-premises networks. Only a single FastConnect or IPSec VPN (connected to the hub VCN) is required for the on-premises network to communicate with all the spoke VCNs.
See the instructions in Setting Up VCN Transit Routing in the Console.
Currently, the spoke VCNs can access your on-premises networks using the hub VCN.
No, the VCN Transit Routing solution only supports consolidated connectivity between VCNs in the same region.
Yes. You control this with the route table associated with the LPG on the hub VCN. You can configure restrictive route rules that specify only the on-premises subnets that you want to make available to the spoke VCN. The routes advertised to the spoke VCN are those in that route table and the hub VCN's CIDR.
Yes. You control this with the route table associated with the DRG on the hub VCN. You can configure restrictive route rules that specify only the spoke VCN subnets that you want to make available to the on-premises network. The routes advertised to the on-premises network are those in that route table and the hub VCN's CIDR.
Yes. The hub VCN is limited to a maximum of 10 local peerings with spoke VCNs.
Yes. You can add a service gateway to a VCN that is connected to your on-premises network by way of FastConnect or VPN Connect. You can then configure route rules on the route tables associated with VCN's DRG and service gateway to direct on-premises traffic through the VCN to the Oracle services of interest. You on-premises hosts can use their private IPs when communicating with the Oracle services, and the traffic does not go over the internet.
For more information, see Transit Routing: Private Access to Oracle Services.
Yes, you can set up transit routing through a private IP in the hub VCN. In this case, you route the traffic to a private IP on the firewall instance in the hub VCN. The firewall instance can inspect all traffic between you on-premises network and spoke VCNs.
If you are routing via a firewall instance (or any other network virtual appliance) in the hub VCN, the performance limits are based on the I/O characteristics of the network virtual appliance. If you're not routing the traffic through a network virtual appliance (and instead routing directly through the hub VCN's gateways), there are no performance limits. The gateways are virtual devices that are highly available and dynamically scale to support the network bandwidth requirements of your network.
The Dynamic Host Configuration Protocol (DHCP) provides a framework for passing configuration information to hosts on an IP network. Configuration parameters and other control information are carried to the instance in the "options" field (RFC 2132) of the DHCP message. Each subnet in a VCN can have a single set of DHCP options associated with it.
You can configure two options that control how instances in your VCN resolve Domain Name System (DNS) hostnames:
When resolving a DNS query, the instance's OS uses the DNS servers specified with DNS Type and appends the Search Domain to the value being queried.
For more information, see DHCP Options.
Yes, you can edit subnet properties to change which set of DHCP options the subnet uses. You can also change the values of the DHCP options.
When you launch an instance, you can specify a hostname for the instance, along with a display name. This hostname, combined with the subnet's domain name, becomes the fully qualified domain name (FQDN) of your instance. This FQDN is unique within the VCN and resolves to the private IP address of your instance. For more details, see DNS in Your Virtual Cloud Network.
Note that to specify a hostname for the instance, the VCN and subnet must be configured to enable DNS hostnames.
When you create a VCN, you can specify its DNS label. This, combined with the parent domain oraclevcn.com, becomes the domain name of the VCN.
When you create a subnet, you can specify its DNS label. This, combined with the VCN's domain name, becomes the domain name of the subnet.
You can enable a hostname for a compute instance only if the VCN and subnet are both created with a DNS label.
A DNS hostname is a name that corresponds to the IP address of an instance connected to a network. In case of an Oracle Cloud Infrastructure VCN, every instance can be configured with a DNS hostname that corresponds to the private IP address of the instance.
A fully qualified domain name (FQDN) of an instance looks like hostname.subnetdnslabel.vcndnslabel.oraclevcn.com, where hostname is the DNS hostname of the instance, subnetdnslabel and vcndnslabel are the DNS labels of the instance's subnet and the VCN respectively.
The parent domain oraclevcn.com is reserved for use with DNS hostnames created in Oracle Cloud Infrastructure.
Yes. DNS hostnames are created for instances regardless of the DNS type selected for the subnet.
No. The instance can resolve hostnames only of instances within the same VCN.
Yes, you can do this with custom DNS servers set up within the VCN. You can configure the custom DNS servers to use 169.254.169.254 as the forwarder for the VCN domain (like contoso.oraclevcn.com).
Note that the custom DNS servers must be configured in a subnet that uses "Internet and VCN Resolver" as the DNS type (to allow access to the 169.254.169.254 IP address).
For an example of an implementation with the Oracle Terraform provider, see Hybrid DNS Configuration.
There is no charge for creating VCNs and using them. However, usage charges for other Oracle Cloud Infrastructure services (including Compute and Block Volumes) and data transfer charges apply at the published rates. There are no data transfer charges for any communication among resources within a VCN.
You are charged only the published Oracle Cloud Infrastructure outbound data transfer rates. There is no hourly or monthly VPN connection charge.
You don’t incur data transfer charges when accessing other public Oracle Cloud Infrastructure services (such as Object Storage) in the same region. All network traffic via private or public IPs between your instances and other resources inside your VCN, (such as a database or load balancer) is free of data transfer charges.
If you access public Oracle Cloud Infrastructure resources via your IPSec VPN from inside your VCN, you incur the published outbound data transfer charges.
Unless otherwise noted, the Oracle Cloud Infrastructure prices, including outbound data transfer charges, exclude applicable taxes and duties, including VAT and any applicable sales tax.