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Networking
This chapter discusses how physical network interface cards (NICs) in XenServer hosts are used to enable
networking within Virtual Machines (VMs). XenServer supports up to 16 physical network interfaces (or up
to 16 of bonded network interfaces) per XenServer host and up to 7 virtual network interfaces per VM.
Note:
XenServer provides automated configuration and management of NICs using the xe command line interface
(CLI). Unlike previous XenServer versions, the host networking configuration files should not be edited
directly in most cases; where a CLI command is available, do not edit the underlying files.
If you are already familiar with XenServer networking concepts, you may want to skip ahead to one of the
following sections:
• For procedures on how to create networks for standalone XenServer hosts, see the section called
“Creating networks in a standalone server”.
• For procedures on how to create networks for XenServer hosts that are configured in a resource pool,
see the section called “Creating networks in resource pools”.
• For procedures on how to create VLANs for XenServer hosts, either standalone or part of a resource
pool, see the section called “Creating VLANs”.
• For procedures on how to create bonds for standalone XenServer hosts, see the section called “Creating
NIC bonds on a standalone host”.
• For procedures on how to create bonds for XenServer hosts that are configured in a resource pool, see
the section called “Creating NIC bonds in resource pools”.
XenServer networking overview
This section describes the general concepts of networking in the XenServer environment.
One network is created for each physical network interface card during XenServer installation. When you
add a server to a resource pool, these default networks are merged so that all physical NICs with the same
device name are attached to the same network.
Typically you would only add a new network if you wished to create an internal network, set up a new VLAN
using an existing NIC, or create a NIC bond.
You can configure three different types of physical (server) networks in XenServer:
• Internal networks have no association to a physical network interface, and can be used to provide
connectivity only between the virtual machines on a given server, with no connection to the outside world.
• External networks have an association with a physical network interface and provide a bridge between
a virtual machine and the physical network interface connected to the network, enabling a virtual machine
to connect to resources available through the server's physical network interface card.
• Bonded networks create a bond between two NICs to create a single, high-performing channel between
the virtual machine and the network.
Note:
Some networking options have different behaviors when used with standalone XenServer hosts compared
to resource pools. This chapter contains sections on general information that applies to both standalone
hosts and pools, followed by specific information and procedures for each.
