Citrix Systems 6 manual Creating Networks in a Standalone Server

Creating cross-server private networks requires Citrix XenServer Advanced editions or higher. To learn more about XenServer editions, and to find out how to upgrade, visit the Citrix website here.

Previous versions of XenServer allowed you to create single-server private networks that allowed VMs running on the same host to communicate with each other. The cross-server private network feature, which extends the single-server private network concept to allow VMs on different hosts to communicate with each other. Cross- server private networks combine the same isolation properties of a single-server private network but with the additional ability to span hosts across a resource pool. This combination enables use of VM agility features such as XenMotion live migration and Workload Balancing (WLB) for VMs with connections to cross-server private networks.

Cross-server private networks are completely isolated. VMs that are not connected to the private network cannot sniff or inject traffic into the network, even when they are located on the same physical host with VIFs connected to a network on the same underlying physical network device (PIF). VLANs provide similar functionality, though unlike VLANs, cross-server private networks provide isolation without requiring configuration of a physical switch fabric, through the use of the Generic Routing Encapsulation (GRE) IP tunnelling protocol.

Private networks provide the following benefits without requiring a physical switch:

•the isolation properties of single-server private networks

•the ability to span a resource pool, enabling VMs connected to a private network to live on multiple hosts within the same pool

•compatibility with features such as XenMotion and Workload Balancing

Cross-Server Private Networks must be created on a management interface, as they require an IP addressable PIF. Any IP-enabled PIF (referred to as a 'Management Interface' in XenCenter) can be used as the underlying network transport. If you choose to put cross-server private network traffic on a second management interface, then this second management interface must be on a separate subnet.

If both management interfaces are on the same subnet, traffic will be routed incorrectly.

Note:

To create a cross-server private network, the following conditions must be met:

•All of the hosts in the pool must be using XenServer 6.0 or greater

•All of the hosts in the pool must be using the vSwitch for the networking stack

•The vSwitch Controller must be running and you must have added the pool to it (The pool must have a vSwitch Controller configured that handles the initialization and configuration tasks required for the vSwitch connection)

•The cross-server private network must be created on a NIC configured as a management interface. This can be the primary management interface or another management interface (IP-enabled PIF) you configure specifically for this purpose, provided it is on a separate subnet.

For more information on configuring the vSwitch, see the XenServer vSwitch Controller User Guide. For UI-based procedures for configuring private networks, see the XenCenter Help.

Creating Networks in a Standalone Server

Because external networks are created for each PIF during host installation, creating additional networks is typically only required to:

•use a private network

•support advanced operations such as VLANs or NIC bonding

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