IBM Power Systems Infrastructure environment introduction

Networking VLANs and Subnets

The following information is a summary of Configuring connectivity to Power Systems Virtual Server and Configuring and adding a private network subnet.

The Virtual LAN (VLAN) on the IBM Power Systems Infrastructure network, provides an enterprise-grade private network with full isolation and security. Each VLAN is Public or Private, and is assigned to a specific data center for a specific IBM Cloud Account.

Each VLAN is associated with a single Subnet, for example:

• Public VLAN (only one per region)
  • Public Subnet
• Private VLAN
  • Private Subnet

A Public Subnet is the quickest and simplest way to connect to a IBM Power Virtual Server instance. The public network is protected by a firewall and only the following network protocols are allowed:

• SSH (port 22)
• HTTPS (port 443)
• Ping (ICMP)
• IBM i 5250 console emulation with SSL (port 992)

For the public network, other ports are blocked and can be routed through SSH.

A Private Subnet is required for the connection of your virtual instances with systems outside of the IBM data centers and for communication between multiple instances in an SAP three-tier system. This subnet is an internal network that can be used to connect individual IBM Power Virtual Servers with each other.

If you want to separate different types of network traffic in your landscape, you can order more subnets (and their respective VLANs).

Keep in mind that the additional VLANs and subnets lead to traffic segregation, not increased performance; the increased performance is gained when additional VLANs and Subnets are associated to a host. When multiple network interfaces are used, two performance increases are possible depending on the use case:

• Bonding of the network interfaces, creating a network path with the network throughput of both interfaces
• Traffic segregation using two networks, then isolating high volumes of traffic to a specific network which avoids a single network becoming a bottleneck. For example, a network for storage I/O only

With IBM Power Virtual Server as an example, a single threaded Linux network interface may reach 100% CPU Thread utilization even though the performance limits of the network path itself are still not reached. Additional network interfaces attached to another VLAN and Subnet will therefore increase performance

By default, your server has a Private IP address. If you use public subnets, a public IP address is assigned in addition.

Networking connectivity

Issues with network connectivity can cause delays for your project if you do not plan properly, regardless of how you plan to use your system.

If you need to connect to your virtual server through the public internet, in other words, inbound to a virtual server, you can order Public IPs and attach them to the virtual server per vNIC.

Various interconnectivity options available, for example:

• IBM Power Systems Infrastructure bridged to IBM Cloud Classic Infrastructure
• IBM Power Systems Infrastructure bridged to IBM Cloud VPC Infrastructure
• IBM Power Systems Infrastructure bridged to on-premises data centers by using IBM Direct Link

IBM Cloud Direct Link on Classic must be used to connect your IBM Power Virtual Servers with your IBM Cloud Classic Infrastructure and VPC Infrastructure resources.

After you configure Direct Link on Classic, you must configure routing on your virtual server instance. For more information, see Adding routes on your instance for the jump server.

Direct Link on Classic is also used for closer integration into your backbone infrastructure, for more information, see Connectivity to your SAP system landscape.

For more explanation information about IBM Power Systems Infrastructure, see IBM Power Virtual Servers.

Have your networking department contact the IBM Power Virtual Servers Support Team, handled by using IBM Cloud Support after you determine the layout of your landscape and the connectivity that is required on the SAP application layer.