XenServer Networking Configuration

Keeping in mind this diagram:

{{http://wiki.openstack.org/XenServer/XenXCPAndXenServer?action=AttachFile&do=get&target=XenServer-dom0-domU.png}}

Key Points

We are assuming the XenServer has three physical interfaces: eth0, eth1, eth2
This means Dom0 has the following bridges: xenbr0, xenbr1, xenbr2
The Dom0 also has the host local xenapi network, usually the XenServer has the address 169.254.0.1

DomU config:

The DomU is a PV virtual machine (has a kernel with the para-virtualization extensions)
It generally has four interfaces

    eth0 -> connected to xenapi (xapi trafic)
    eth1 -> xenbr2 Tenant network traffic
    eth2 -> xenbr0 Management traffic (MySQL, RabbitMQ, Glance, etc)
    eth3 -> xenbr1 Public traffic (floating ip, api endpoints)

Flags you probably want to know about

Each have the DevStack setting and the nova.conf entry

Public Interface

The interface on ""DomU"" that connects to the public network. Used by nova-network so it sends the floating ip traffic on the correct network.

PUBLIC_INTERFACE=eth3 # DevStack
public_interface=eth3 # nova.conf

Guest Interfaces

The interface on ""XenServer"" that has Tenant (also called VM instance or Guest) traffic.

It should be the same interface as the (trunk) bridge your DomU's tenant network is attached to.

GUEST_INTERFACE=eth2

This changes the following two flags:

vlan_interface=eth2

This is the XenServer interface on which a bridge on the correct VLAN will be created, and then the VM will be attached to that bridge

flat_interface=eth2

This is the XenServer interface the bridge on which the instance traffic will sit on

Flat Network Bridge

Only needed if you are using Flat or FlatDHCP.

This is the XenServer bridge on which the VM instances will have their VIFs attached. This should be the same has the bridge your DomU's Guest Interface is attached to.

FLAT_NETWORK_BRIDGE=xenbr2
flat_network_bridge=xenbr2

Networking Modes

Flat Networking

This requires the Network address to be injected into the VM image. This is currently quite error prone (needs appropriate guest agent software, or injects files into an ubuntu file system)

FlatDHCP Networking

This used DHCP to hand out IP address to the guest VMs.

Most details are covered in the manual:

http://docs.openstack.org/trunk/openstack-compute/admin/content/configuring-flat-dhcp-networking.html

It should look a bit like this:

File:XenServer$$NetworkingFlags$flatdhcp.png

VLAN Networking

Most details are covered in the manual:

http://docs.openstack.org/trunk/openstack-compute/admin/content/configuring-flat-networking.html

Some more pointers are given here:

XenServer/VLANManager

There are extra flags for the compute network driver, (so the VLAN network bridges are correctly created on the XenServer):

network_driver=nova.virt.xenapi.vif.XenAPIBridgeDriver
or
network_driver=nova.virt.xenapi.vif.XenAPIOpenVswitchDriver

It could look at bit like this (notice the bridges that are automatically created by nova are in dotted lines):

File:XenServer$$NetworkingFlags$vlan.png

Network HA

This works the same on XenServer as any other hypervisor: nova-network must be run on every compute host, and the following flag must be set:

multi_host=True

It is know to work well with FlatDHCP, but should work with the over modes too (TODO - get confirmation)

XenServer/NetworkingFlags