Nic emulation supported by xen

The following emulated network interface cards are available for Xen HVM guests in Xen 3.4:

• e100
• e1000
• rtl8139
• ne2k_pci
• pcnet

Emulation is done by Qemu-dm running for each Xen HVM guest. Intel e1000 is known to be the best performing emulated NIC. Even faster is to use PV-on-HVM drivers, which totally bypasses emulation.

Xen - Adding Multiple Network Interface

You can add multiple Network Interfaces for each guest machines


Example : XEN with 3 Network interfaces :

Create a script   :     /etc/xen/scripts/multi-network-script



add following lines to it


#!/bin/sh
dir=$(dirname "$0")
"$dir/network-bridge" "$@" vifnum=0 netdev=eth0 bridge=xenbr0
"$dir/network-bridge" "$@" vifnum=1 netdev=eth1 bridge=xenbr1
"$dir/network-bridge" "$@" vifnum=2 netdev=eth2 bridge=xenbr2


It will create 3 vif and bridges and connect it with physical 3 interfaces


give permission to it

chmod +x /etc/xen/scripts/multi-network-script


add your new script in

xend-config.sxp

edit your  xend-config.sxp

 
replace (network-script network-bridge)  with   (network-script multi-network-bridge)

save it ...

Now Restart Xen Deamon


[root@vps scripts]# service xend restart
restart xend:                                                           [  OK  ]


Now you can see your 3 bridges by ifconfig command

You can configure network interfaces on each domu guests by adding this lines to their config files

vif = ['ip=ipaddress,mac=macaddress,bridge=bridgeinterfaceno']

In this example we are assigning ip address, mac address and binding it with bridge0 interface

# use eth0 for this DomU
vif = ['ip=10.0.1.1,mac=00:16:de:ad:fa:ce,bridge=xenbr0']
...

Installing HVM in xen

Use this command to confirm about your processor support for Virtulization

xm dmesg | grep -i hvm

if you are using intel processor with virtulization supoort you will get this result

(XEN) HVM: VMX enabled

Installing HVM Guest : 

> Create Harddisk image for guest 

dd if=/dev/zero of=/home/xen1.example.com.img bs=1024k count=4000

http://www.howtoforge.com/how-to-run-fully-virtualized-guests-hvm-with-xen-3.2-on-debian-lenny-x86_64

Default XEN xend-config.sxp file

# -*- sh -*-

#
# Xend configuration file.
#

# This example configuration is appropriate for an installation that
# utilizes a bridged network configuration. Access to xend via http
# is disabled. 

# Commented out entries show the default for that entry, unless otherwise
# specified.

#(logfile /var/log/xen/xend.log)
#(loglevel DEBUG)

#(xend-http-server no)
(xend-unix-server yes)
#(xend-tcp-xmlrpc-server no)
#(xend-unix-xmlrpc-server yes)
#(xend-relocation-server no)
# The relocation server should be kept desactivated unless using a trusted
# network, the domain virtual memory will be exchanged in raw form without
# encryption of the communication. See also xend-relocation-hosts-allow option

(xend-unix-path /var/lib/xend/xend-socket)

# Port xend should use for the HTTP interface, if xend-http-server is set.
#(xend-port            8000)

# Port xend should use for the relocation interface, if xend-relocation-server
# is set.
#(xend-relocation-port 8002)

# Address xend should listen on for HTTP connections, if xend-http-server is
# set.
# Specifying 'localhost' prevents remote connections.
# Specifying the empty string '' (the default) allows all connections.
#(xend-address '')
#(xend-address localhost)

# Address xend should listen on for relocation-socket connections, if
# xend-relocation-server is set.
# Meaning and default as for xend-address above.
#(xend-relocation-address '')

# The hosts allowed to talk to the relocation port.  If this is empty (the
# default), then all connections are allowed (assuming that the connection
# arrives on a port and interface on which we are listening; see
# xend-relocation-port and xend-relocation-address above).  Otherwise, this
# should be a space-separated sequence of regular expressions.  Any host with
# a fully-qualified domain name or an IP address that matches one of these
# regular expressions will be accepted.
#
# For example:
#  (xend-relocation-hosts-allow '^localhost$ ^.*\.example\.org$')
#
#(xend-relocation-hosts-allow '')
(xend-relocation-hosts-allow '^localhost$ ^localhost\\.localdomain$')

# The limit (in kilobytes) on the size of the console buffer
#(console-limit 1024)

##
# To bridge network traffic, like this:
#
# dom0: fake eth0 -> vif0.0 -+
#                            |
#                          bridge -> real eth0 -> the network
#                            |
# domU: fake eth0 -> vifN.0 -+
#
# use
#
# (network-script network-bridge)
#
# Your default ethernet device is used as the outgoing interface, by default.
# To use a different one (e.g. eth1) use
#
# (network-script 'network-bridge netdev=eth1')
#
# The bridge is named xenbr0, by default.  To rename the bridge, use
#
# (network-script 'network-bridge bridge=<name>')
#
# It is possible to use the network-bridge script in more complicated
# scenarios, such as having two outgoing interfaces, with two bridges, and
# two fake interfaces per guest domain.  To do things like this, write
# yourself a wrapper script, and call network-bridge from it, as appropriate.
#
(network-script network-bridge)

# The script used to control virtual interfaces.  This can be overridden on a
# per-vif basis when creating a domain or a configuring a new vif.  The
# vif-bridge script is designed for use with the network-bridge script, or
# similar configurations.
#
# If you have overridden the bridge name using
# (network-script 'network-bridge bridge=<name>') then you may wish to do the
# same here.  The bridge name can also be set when creating a domain or
# configuring a new vif, but a value specified here would act as a default.
#
# If you are using only one bridge, the vif-bridge script will discover that,
# so there is no need to specify it explicitly.
#
(vif-script vif-bridge)


## Use the following if network traffic is routed, as an alternative to the
# settings for bridged networking given above.
#(network-script network-route)
#(vif-script     vif-route)


## Use the following if network traffic is routed with NAT, as an alternative
# to the settings for bridged networking given above.
#(network-script network-nat)
#(vif-script     vif-nat)


# Dom0 will balloon out when needed to free memory for domU.
# dom0-min-mem is the lowest memory level (in MB) dom0 will get down to.
# If dom0-min-mem=0, dom0 will never balloon out.
(dom0-min-mem 256)

# In SMP system, dom0 will use dom0-cpus # of CPUS
# If dom0-cpus = 0, dom0 will take all cpus available
(dom0-cpus 0)

# Whether to enable core-dumps when domains crash.
#(enable-dump no)

# The tool used for initiating virtual TPM migration
#(external-migration-tool '')

# The interface for VNC servers to listen on. Defaults
# to 127.0.0.1  To restore old 'listen everywhere' behaviour
# set this to 0.0.0.0
#(vnc-listen '127.0.0.1')
 
# The default password for VNC console on HVM domain.
# Empty string is no authentication.
(vncpasswd '')

# The default keymap to use for the VM's virtual keyboard
# when not specified in VM's configuration
(keymap 'en-us')

# The VNC server can be told to negotiate a TLS session
# to encryption all traffic, and provide x509 cert to
# clients enalbing them to verify server identity. The
# GTK-VNC widget, virt-viewer, virt-manager and VeNCrypt
# all support the VNC extension for TLS used in QEMU. The
# TightVNC/RealVNC/UltraVNC clients do not.
#
# To enable this create x509 certificates / keys in the
# directory /etc/xen/vnc
#
#  ca-cert.pem       - The CA certificate
#  server-cert.pem   - The Server certificate signed by the CA
#  server-key.pem    - The server private key
#
# and then uncomment this next line
# (vnc-tls 1)
#
# The certificate dir can be pointed elsewhere..
#
# (vnc-x509-cert-dir /etc/xen/vnc)
#
# The server can be told to request & validate an x509
# certificate from the client. Only clients with a cert
# signed by the trusted CA will be able to connect. This
# is more secure the password auth alone. Passwd auth can
# used at the same time if desired. To enable client cert
# checking uncomment this:
#
# (vnc-x509-verify 1)

# Allow probing of disk image file format.  This is insecure!  It lets
# a malicious domU read any file in dom0.  Applies only to fully
# virtual domUs.  Required for using formats other than raw.
#(enable-image-format-probing no)

# Number of seconds xend will wait for device creation
#(device-create-timeout 100)

# Strict checking when doing PCI passthrough; enabled by default
#(pci-dev-assign-strict-check yes)

Xen HVM

check HVM capabilities : 

[root@localhost]# xm info|grep xen_caps
xen_caps               : xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p

[root@localhost]# xm dmesg | grep -i hvm
(XEN) HVM: VMX enabled

VNC on HVM guests

Enable following options in configuration file /etc/xen/xen-config.sxp

(network-script network-bridge)
(vnc-listen '127.0.0.1')
(vncpasswd '...')

VNC password is created with /usr/bin/vncpasswd


 virsh # dumpxml firewall
<domain type='xen' id='1'>
  <name>firewall</name>
  <uuid>e816f20f-1ada-0c43-5323-91fbed2a1c27</uuid>
  <memory>524288</memory>
  <currentMemory>524288</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type>hvm</type>
    <loader>/usr/lib/xen/boot/hvmloader</loader>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/lib/xen/bin/qemu-dm</emulator>
    <disk type='file' device='disk'>
      <driver name='file'/>
      <source file='/vm/firewall.img'/>
      <target dev='hda' bus='ide'/>
    </disk>
    <disk type='file' device='cdrom'>
      <target dev='hdc' bus='ide'/>
      <readonly/>
    </disk>
    <interface type='bridge'>
      <mac address='00:16:36:1d:26:bf'/>
      <source bridge='xenbr0'/>
      <script path='vif-bridge'/>
      <target dev='vif1.0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/1'/>
      <target port='0'/>
    </serial>
    <console type='pty' tty='/dev/pts/1'>
      <source path='/dev/pts/1'/>
      <target port='0'/>
    </console>
  </devices>
</domain>

sample : 

name = "rhel4u4-x86_64"
builder = "hvm"
memory = "500"
disk = [ 'file:/var/lib/xen/images/rhel4u4-x86_64.dsk,hda,w', ]
vif = [ 'type=ioemu, mac=00:16:3e:09:f0:12, bridge=xenbr0', 'type=ioemu, 
mac=00:16:3e:09:f0:13, bridge=xenbr1' ]
uuid = "b10372f9-91d7-a05f-12ff-372100c99af5"
device_model = "/usr/lib64/xen/bin/qemu-dm"
kernel = "/usr/lib/xen/boot/hvmloader"
vnc=1
vncunused=1
apic=1
acpi=1
pae=1
vcpus=1
serial = "pty" # enable serial console
on_reboot   = 'restart'