Oracle Cloud Infrastructure Documentation

Network Setup for Exadata DB Systems

Before you set up an Exadata DB system, you must set up a virtual cloud network (VCN) and other Networking service components. This topic describes the recommended configuration for the VCN and several related requirements for the Exadata DB system.

VCN and Subnets

To launch an Exadata DB system, you must have:

  • A VCN in the region where you want the DB system
  • At least two subnets in the VCN. The two subnets are:

    • Client subnet
    • Backup subnet

In general, Oracle recommends using A subnet that spans all availability domains (ADs) in the region. Oracle recommends using regional subnets because they are more flexible and make it easier to implement failover across ADs. Compare with AD-specific subnets., which span all One or more isolated, fault-tolerant Oracle data centers that host cloud resources such as instances, volumes, and subnets. A region contains one or more availability domains. in the region. If you instead use A subnet that is specific to a particular availability domain (AD). Historically all subnets were AD-specific. Compare with regional subnets, which Oracle recommends over AD-specific subnets., both the client and backup subnets must be in the same availability domain. The important thing to know for your DB system is that the resources you create in the two subnets must be in the same availability domain. For more information, see About Regional Subnets.

You will create custom Virtual route table for your VCN that provides mapping for the traffic from subnets via gateways to external destinations.for each subnet. You will also create Virtual firewall rules for your VCN. Each security rule specifies a type of ingress or egress traffic allowed in or out of a resource or VNIC. Also see network security groups and security lists. to control traffic to and from the client network and backup network of the Exadata compute notes. More information follows about those items.

Option 1: Public Client Subnet with Internet Gateway

This option can be useful when doing a proof-of-concept or development work. You can use this setup in production if you want to use an An optional virtual router that you can add to your VCN. It provides a path for network traffic between your VCN and the internet. with the VCN, or if you have services that run only on a public network and need access to the database. See the following diagram and description.

This image shows the network setup with a public client subnet.

You set up:

Important

See this known issue for information about configuring route rules with service gateway as the target on route tables associated with public subnets.

Option 2: Private Subnets

Oracle recommends this option for a production system. Both subnets are private and cannot be reached from the internet. See the following diagram and description.

This image shows the network setup with a private client subnet.

You set up:

  • Subnets:

    • Private client subnet.
    • Private backup subnet.
  • Gateways for the VCN:

  • Route tables:

    • Custom route table for the private client subnet, with two rules:

      • A rule for the on-premises network's CIDR, and target = DRG.
      • A rule for the service CIDR label called All <region> Services in Oracle Services Network, and target = the service gateway. The Oracle Services Network is a conceptual network in Oracle Cloud Infrastructure that is reserved for Oracle services. The rule enables the client subnet to reach the regional Oracle YUM repo for OS updates. Also see Option 2: Service Gateway Access to Both Object Storage and YUM Repos.
      • A rule for 0.0.0.0/0, and target = NAT gateway.
    • Separate custom route table for the private backup subnet, with one rule:
      • The same rule as for the client subnet: for the service CIDR label called All <region> Services in Oracle Services Network, and target = the service gateway. This rule enables the backup subnet to reach the regional Object Storage for backups.
  • Security rules to enable the desired traffic to and from the Exadata nodes. See Security Rules for the Exadata System.
  • Static route on the DB system's compute nodes (to enable access to Object Storage by way of the backup subnet).

Requirements for IP Address Space

If you're setting up Exadata DB systems (and thus VCNs) in more than one region, make sure the IP address space of the VCNs does not overlap. This is important if you want to set up disaster recovery with Oracle Data Guard.

The two subnets you create for the Exadata DB system must not overlap with 192.168.128.0/20.

The following table lists the minimum required subnet sizes, depending on the Exadata rack size. For the client subnet, each node requires two IP addresses, and in addition, three addresses are reserved for Single Client Access Names (SCANs). For the backup subnet, each node requires one address.

Tip

The Networking service reserves three IP addresses in each subnet. Allocating a larger space for the subnet than the minimum required (for example, at least /25 instead of /28) can reduce the relative impact of those reserved addresses on the subnet's available space.

Rack Size Client Subnet: # Required IP Addresses Client Subnet: Minimum Size Backup Subnet: # Required IP Addresses Backup Subnet: Minimum Size
Base System or Quarter Rack

(2 addresses * 2 nodes) + 3 for SCANs + 3 reserved in subnet = 10

 

/28 (16 IP addresses) (1 address * 2 nodes) + 3 reserved in subnet = 5 /29 (8 IP addresses)
Half Rack (2 * 4 nodes) + 3 + 3 = 14 /28 (16 IP addresses) (1 * 4 nodes) + 3 = 7 /29 (8 IP addresses)
Full Rack (2* 8 nodes) + 3 + 3 = 22 /27 (32 IP addresses) (1 * 8 nodes) + 3 = 11 /28 (16 IP addresses)

VCN Creation Wizard: Not for Production

The Networking section of the Console includes a handy wizard that creates a VCN along with related resources. It can be useful if you just want to try launching an instance. However, the wizard automatically chooses the address ranges and creates public subnets and an internet gateway. You may not want this for your production network, so Oracle recommends you create the VCN and other resources individually yourself instead of using the wizard.

DNS: Short Names for the VCN, Subnets, and DB System

For the nodes to communicate, the VCN must use the Internet and VCN Resolver. It enables hostname assignment to the nodes, and DNS resolution of those hostnames by resources in the VCN. It enables round robin resolution of the database's SCANs. It also enables resolution of important service endpoints required for backing up databases, patching, and updating the cloud tooling on an Exadata DB system. The Internet and VCN Resolver is the VCN's default choice for DNS in the VCN. For more information, see DNS in Your Virtual Cloud Network and also DHCP Options.

When you create the VCN, subnets, and Exadata, you must carefully set the following identifiers, which are related to DNS in the VCN:

  • VCN domain label
  • Subnet domain label
  • Hostname prefix for the Exadata DB system

These values make up the node's fully qualified domain name (FQDN):

<hostname_prefix>-######.<subnet_domain_label>.<vcn_domain_label>.oraclevcn.com

For example:

exacs-abcde1.clientpvtad1.acmevcniad.oraclevcn.com

In this example, you assign exacs as the hostname prefix when you create the Exadata DB system. The Database service automatically appends a hyphen and a five-letter string with the node number at the end. For example:

  • Node 1: exacs-abcde1.clientpvtad1.acmevcniad.oraclevcn.com
  • Node 2: exacs-abcde2.clientpvtad1.acmevcniad.oraclevcn.com
  • Node 3: exacs-abcde3.clientpvtad1.acmevcniad.oraclevcn.com
  • And so on

Requirements for the hostname prefix:

  • Maximum 12 characters
  • Cannot be the string localhost

Requirements for the VCN and subnet domain labels:

  • Recommended maximum: 14 characters each. The actual underlying requirement is a total of 28 characters across both domain labels (excluding the period between the labels). For example, both of these are acceptable: subnetad1.verylongvcnphx or verylongsubnetad1.vcnphx. For simplicity, the recommendation is 14 characters each.
  • No hyphens or underscores.
  • Recommended: include the region name in the VCN's domain label, and include the availability domain name in the subnet's domain label.

<12_chars_max>-######.<14_chars_max>.<14_chars_max>.oraclevcn.com

In general, the FQDN has a maximum total limit of 63 characters.

The preceding maximums are not enforced when you create the VCN and subnets. However, if the labels exceed the maximum, the Exadata deployment fails.

DNS: Between On-Premises Network and VCN

To enable the use of hostnames when on-premises hosts and VCN resources communicate with each other, you have two options:

  • Set up an instance in the VCN to be a custom DNS server. For an example of an implementation of this scenario with the Oracle Terraform provider, see Hybrid DNS Configuration.
  • Manage hostname resolution yourself manually.

Node Access to Object Storage: Static Route

Access to Oracle Cloud Infrastructure Object Storage is required for backing up databases, patching, and updating the cloud tooling on an Exadata DB system. Regardless of how you set up the VCN with that access (for example, with a service gateway), you must configure a static route to Object Storage on each of the compute nodes in the cluster. This is required because, by default, all traffic in an Exadata DB system is routed through the data network. You need the traffic destined for Object Storage to be routed instead through the backup interface (BONDETH1).

Important

You must configure a static route for Object Storage access on each compute node in an Exadata DB system. Otherwise, attempts to back up databases, patch, or update tooling on the system might fail.

Object Storage IP allocations
To configure a static route for Object Storage access

Service Gateway for the VCN

Your VCN needs access to both Object Storage for backups and Oracle YUM repos for OS updates.

Depending on whether you use option 1 or option 2 described previously, you use the service gateway in different ways. See the next two sections.

Option 1: Service Gateway Access Only to Object Storage
Option 2: Service Gateway Access to Both Object Storage and YUM Repos

Security Rules for the Exadata System

This section lists the security rules to use with your Exadata system. Security rules control the types of traffic allowed for the client network and backup network of the Exadata's compute nodes. The rules are divided into three sections.

There are different ways to implement these rules. For more information, see Ways to Implement the Security Rules.

Rules Required for Both the Client Network and Backup Network

This section has several general rules that enable essential connectivity for hosts in the VCN.

If you use security lists to implement your security rules: the following rules are included by default in the default security list.

General ingress rule 1: Allows SSH traffic from anywhere
General ingress rule 2: Allows Path MTU Discovery fragmentation messages
General ingress rule 3: Allows connectivity error messages within the VCN
General egress rule 1: Allows all egress traffic

Rules Required Specifically for the Client Network

The following security rules are important for the client network.

Client ingress rule 1: Allows ONS and FAN traffic from within the client subnet
Client ingress rule 2: Allows SQL*NET traffic from within the client subnet

Important

The two preceding client ingress rules only cover connections initiated from within the client subnet. If you have a client that resides outside the VCN, Oracle recommends setting up two additional similar rules that instead have the Source CIDR set to the public IP address of the client.

The next four rules (two ingress, two egress) allow TCP and ICMP traffic inside the client network and enable the nodes to communicate with each other. If TCP connectivity fails across the nodes, the Exadata DB system fails to provision.

Client ingress rule 3: Allows all TCP traffic inside the client subnet
Client ingress rule 4: Allows all ICMP traffic inside the client subnet
Client egress rule 1: Allows all TCP traffic inside the client subnet
Client egress rule 2: Allows all ICMP traffic inside the client subnet

The next egress rule is important because it allows connections to the Oracle YUM repos. It is redundant with the general egress rule in Rules Required for Both the Client Network and Backup Network (and in the default security list). It is optional but recommended in case the general egress rule (or default security list) is inadvertently changed.

Client egress rule 3: Allows all egress traffic

Rule Required Specifically for the Backup Network

The following security rule is important for the backup network because it enables the DB system to communicate with Object Storage through the service gateway (and optionally with the Oracle YUM repos if the client network doesn't have access to them). It is redundant with the general egress rule in Rules Required for Both the Client Network and Backup Network (and in the default security list). It is optional but recommended in case the general egress rule (or default security list) is inadvertently changed.

Backup egress rule: Allows access to Object Storage

Ways to Implement the Security Rules

The Networking service offers two ways to implement security rules within your VCN:

For a comparison of the two methods, see Comparison of Security Lists and Network Security Groups.

If you use network security groups
If you use security lists