{"id":7744,"date":"2020-09-24T12:03:01","date_gmt":"2020-09-24T12:03:01","guid":{"rendered":"https:\/\/rax-stg-wp-aws.com\/blogs\/components-of-the-oracle-cloud-infrastructure-network\/"},"modified":"2026-11-03T19:29:01","modified_gmt":"2026-11-03T19:29:01","slug":"components-of-the-oracle-cloud-infrastructure-network","status":"publish","type":"blogs","link":"https:\/\/www.rackspace.com\/en-gb\/blogs\/components-of-the-oracle-cloud-infrastructure-network\/","title":{"rendered":"Components of the Oracle Cloud Infrastructure Network"},"content":{"rendered":"<p><strong>Introduction<\/strong><\/p>\n<p>This post gives an overview of the components that are part of the Oracle\u00ae&nbsp;Cloud Infrastructure (OCI) network.&nbsp;<\/p>\n<p>An OCI network comprises the following components:<\/p>\n<ul>\n<li>Virtual Cloud Network<\/li>\n<li>Subnet<\/li>\n<li>Virtual network interface card<\/li>\n<li>Security Lists<\/li>\n<li>Route tables<\/li>\n<li>Route rules<\/li>\n<\/ul>\n<p><strong>Virtual Cloud Network&nbsp;<\/strong><\/p>\n<p>You need to create a Virtual Cloud Network (VCN) before you launch an instance&nbsp;to work in an OCI network. The VCN is like the traditional data center network&nbsp;and includes subnets, route tables, and gateways.<\/p>\n<p>The VCN resides within a single region but can cross multiple availability&nbsp;domains (AD) that cover a single, contiguous IPv4 Classless Inter-Domain Routing&nbsp;(CIDR) block. When you delete a VCN, you should remove the attached gateways and<br \/>\nmake sure the subnets are empty.<\/p>\n<p>VCNs automatically come with the following default components that you cannot&nbsp;delete:<\/p>\n<ul>\n<li>Route table, with no rules<\/li>\n<li>Security list, with default rules<\/li>\n<li>Dynamic Host Configuration Protocol (DHCP) options, with default values.<\/li>\n<\/ul>\n<p>Each subnet you create has the following components associated with it:<\/p>\n<ul>\n<li>One route table<\/li>\n<li>One or more security lists<\/li>\n<li>One set of DHCP options<\/li>\n<\/ul>\n<p>If you do not specify the preceding components, the subnet automatically uses&nbsp;the default VCN components.<\/p>\n<p><strong>Subnet<\/strong><\/p>\n<p>A subnet is a subdivision of the VCN and can be either a specific or regional&nbsp;AD. Oracle recommends using regional subnets because they are more flexible.<\/p>\n<p>You can have multiple subnets in an AD that use the same route table, security&nbsp;lists, and DHCP options. Subnets contain virtual network interface cards,&nbsp;which are attached to the instances. Each subnet has a contiguous range of IPs,&nbsp;and the IP ranges cannot overlap.<\/p>\n<p>You can designate subnets as either of the following choices:<\/p>\n<ul>\n<li><strong>Private<\/strong>: Instances contain private IP addresses assigned to the VNICs.<\/li>\n<li><strong>Public<\/strong>: Instances have both private and public IP addresses assigned to the VNICs.<\/li>\n<\/ul>\n<p>In the following diagram, the ADs each have one or more data centers located&nbsp;within a region (local geographical area). The region is composed of three&nbsp;availability domains.<\/p>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/blog_article_images\/26485-body-Picture1_22.png\" alt=\"OCI Pic 1\" \/><\/p>\n<p>&nbsp;<a href=\"https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/managingVCNs.htm](https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/managingVCNs.htm\"><em>Image Source<\/em><\/a><\/p>\n<p><strong>Virtual network interface card<\/strong><\/p>\n<p>A virtual network interface card (VNIC) enables an instance to connect to a VCN&nbsp;and determines how the instance connects with endpoints inside and outside of a&nbsp;VCN.<\/p>\n<p>The primary VNIC is attached to each instance during launch, and you cannot&nbsp;remove it. You can attach secondary VNICs and remove them from an existing&nbsp;instance that is in the same availability domain as the primary VNIC.<\/p>\n<p><strong>Security lists<\/strong><br \/>\nSecurity lists &nbsp;are virtual firewall rules for the VCN and provide information&nbsp;about the following types of traffic:<\/p>\n<ul>\n<li>&nbsp;<strong>Ingress<\/strong>: Incoming traffic<\/li>\n<li>&nbsp;<strong>Egress<\/strong>: Outgoing traffic<\/li>\n<\/ul>\n<p>There are two types of rules:<\/p>\n<ul>\n<li><strong>Stateful<\/strong>: Uses connection tracking for any traffic that matches that rule<\/li>\n<li><strong>Stateless<\/strong>: Does not use connection tracking for any traffic that matches that rule&nbsp;<\/li>\n<\/ul>\n<p>The security rules are enforced at an instance level, even though they are<br \/>\nassociated at the subnet level.<\/p>\n<p><strong>Route tables<\/strong><\/p>\n<p>Use route tables to send traffic out of the VCN, which consists of route rules&nbsp;with the following elements:<\/p>\n<ul>\n<li>Destination CIDR Routing<\/li>\n<li>Targets for the traffic that matches that CIDR<\/li>\n<\/ul>\n<p><strong>Route rules&nbsp;<\/strong><\/p>\n<p>You don&#8217;t need route rules to enable traffic within the VCN itself.&nbsp;Permissible target types for route rules include the following ones:<\/p>\n<p><strong>Dynamic routing gateway<\/strong><\/p>\n<p>A dynamic routing gateway routes private network traffic between your VCN and&nbsp;on-premises network by using either an IPSec VPN, FastConnect, or a peered VCN&nbsp;in another region.<\/p>\n<p><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/blog_article_images\/26485-body-Picture2_14.png\" alt=\"OCI Pic 2\" \/><\/p>\n<p><a href=\"https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/overviewIPsec.htm](https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/overviewIPsec.htm\"><em>Image Source<\/em><\/a>&nbsp;<\/p>\n<p><strong>Internet gateway<\/strong><\/p>\n<p>Use an Internet gateway for public subnets that access the Internet directly.&nbsp;The public subnet must have a route table and use a security list to control&nbsp;the traffic in and out of the resources. Internet gateways support connections&nbsp;initiated within VCN and from the Internet, such as from web servers.<\/p>\n<p><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/blog_article_images\/26485-body-Picture3_11.png\" alt=\"OCI Pic 3\" \/><\/p>\n<p><a href=\"https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/managingIGs.htm](https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/managingIGs.htm\"><em>Image Source<\/em><\/a>&nbsp;<\/p>\n<p><strong>Network Address Translation gateway<\/strong><\/p>\n<p>Use a Network Address Translation (NAT) gateway for resources that have the&nbsp;following qualities:<\/p>\n<ul>\n<li>Do not have public IP addresses<\/li>\n<li>Need outbound access to the Internet<\/li>\n<li>Cannot receive inbound connections initiated from the Internet<\/li>\n<\/ul>\n<p>The public IP is automatically assigned to the NAT gateway, and you cannot&nbsp;choose or use the reserved public IP addresses. A database system that needs to&nbsp;download patches from the Internet might use a NAT gateway.&nbsp;<\/p>\n<p><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/blog_article_images\/26485-body-Picture4_6.png\" alt=\"OCI Pic 4\" \/><\/p>\n<p>&nbsp;<a href=\"https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/servicegateway.htm\"><em>Image Source<\/em><\/a><\/p>\n<p>&nbsp;<\/p>\n<p><strong>Service gateway<\/strong><\/p>\n<p>Use a service gateway for subnets that need private access to Oracle services,&nbsp;such as an autonomous database.&nbsp;<\/p>\n<p><strong>&nbsp;Local Peering gateway<\/strong><\/p>\n<p>The subnets that need private access to a peered VCN in the same region communicate&nbsp;by using private IP addresses. The two VCNs in the peering network cannot have&nbsp;overlapping CIDRs.<\/p>\n<p><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/blog_article_images\/26485-body-Picture6_4.png\" alt=\"OCI Pic 6\" \/><\/p>\n<p><em><a href=\"https:\/\/docs.cloud.oracle.com\/en-us\/iaas\/Content\/Network\/Tasks\/localVCNpeering.htm\">Image Source<\/a><\/em>&nbsp;<\/p>\n<p><strong>Conclusion<\/strong><\/p>\n<p>Set up your OCI network by creating the VCN, subnets, internet gateway, NAT&nbsp;gateway, and service gateway with basic security list rules. In just a couple of&nbsp;guided steps in the <strong>Virtual Networking QuickStart<\/strong>&nbsp;wizard console, you can&nbsp;quickly create the VCN and other components described in this post.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Components of the Oracle Cloud Infrastructure Network<\/p>\n","protected":false},"author":2,"featured_media":7746,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","format":"standard","meta":{"content-type":"","nid":"26485","content_type":"blog","created_by":"10130","authored_on":"2024-01-14T13:03:01+00:00","field_article_industries":"","tag_category":"Technical","field_blog_author_text":"by Rackspace Technology Staff","seo_description":"Understand essential components of Oracle Cloud Infrastructure network. Grasp the architecture of OCI network comprehensively.\r\n","field_featured_image":"","insights_image":"\/wp-content\/uploads\/2026\/blog_technical_images\/26485-insights_image-oracle-technical-blog-1-insights.jpg","field_partners":"","rxt_platforms":"Oracle, Oracle Cloud Infrastructure","product":"","publisheddate":"2020-09-24T12:03:01","rxt_solutions":"Cloud Adoption & Migration, Cloud Management & Operations, Public Cloud","opengraph_tag":"","x_tag":"","teaser_flag":"Technical Blog","seo_titile":"Overview Oracle Cloud Infrastructure Network | Rackspace","field_topics":"","field_slug":"components-of-the-oracle-cloud-infrastructure-network","footnotes":""},"categories":[178],"tags":[204],"class_list":["post-7744","blogs","type-blogs","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","tag-technical"],"_links":{"self":[{"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/blogs\/7744","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/blogs"}],"about":[{"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/types\/blogs"}],"author":[{"embeddable":true,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/comments?post=7744"}],"version-history":[{"count":3,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/blogs\/7744\/revisions"}],"predecessor-version":[{"id":9651,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/blogs\/7744\/revisions\/9651"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/media\/7746"}],"wp:attachment":[{"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/media?parent=7744"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/categories?post=7744"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rackspace.com\/en-gb\/wp-json\/wp\/v2\/tags?post=7744"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}