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====== XenServer Networking Notes ======

See also **[[virtualization:xenserver:xenserver_add_nic|Xenserver - Add or Replace a NIC]]**

See also **[[networking:mtu_test|Testing MTU, Jumbo Frames and Packet Fragmentation]]**

http://support.citrix.com/servlet/KbServlet/download/17424-102-671540/Xen_Networking_in_Linux_final.pdf

===== Management Network =====

  * No Jumbo Frames
  * No VLANs

===== Storage Networks =====

Jumbo Frames are enabled by setting MTU to 9000 on all Storage network interfaces:

  * ZFS Storage Server
  * Virtualization Hosts

Something like:

  - Shutdown all VM's
  - Remove the bond
  - Set the MTU to 9000 on the NIC's
  - Re-create the bond with MTU 9000
  - Start the VM's back up making sure the new bond is listed under the VM's networking

===== Helpful Commands =====

<file>
brctl show

arp -a

ifconfig xenbr0
</file>

==== ''xe'' CLI Examples ====

^XenServer “xe” Command                     ^Comment                                ^
|''xe network-list''                            |List the networks and attributes       |
|''xe pif-list''                                |List interface attributes (UUID values)|
|''xe vif-list''                                |                                       |
|''xe pif-forget uuid=''                        |Forgetting an interface means the Xen host no longer has control. Configure through Linux. |
|''xe pif introduce hostuuid= mac= device=''    |Introducing an interface means all configuration should go through Xen. |
|''xe pif-reconfigure-ip ip=xx.xx.xx.xx uuid='' |Change the IP attributes of management interface. |
|''xe pif-uuid=''                               |                                       |
|''xe vif-uuid=''                               |There are several pif and vif commands for network setup. |
|''xe pif-param-set other-config:ethtool-duplex="full" uuid='' |Usually used to set adapter specific attributes. |
|''xe host-set-hostname-live host-name=<fqdn> host-uuid='' |Change the FQDN of the host. |
|''xe vm-list params=name-label,dom-id''        |Shows VMs and their dom-id to associate with VIF names |

===== VLANs =====

http://discussions.citrix.com/topic/246981-how-to-pass-a-trunked-interface-to-a-vm/

http://support.citrix.com/article/CTX123489

  * VLANs allow a single physical network to support multiple logical networks.
  * To use VLANs with XenServer, the host's NIC must be connected to a VLAN trunk port (switch or router).
  * Creating a VLAN in XenServer is done through the process of creating additional virtual interfaces that correspond to a specific VLAN tag. This is done through the XenCenter Host Network tab by adding an External network name and assigning an NIC with a VLAN number.
  * XenServer VLANs are represented by additional PIF objects representing VLAN interfaces corresponding to a specified VLAN tag.
  * XenServer networks can then be connected to the PIF representing the physical NIC to see all traffic on the NIC, or to a PIF representing a VLAN to see only the traffic with the specified VLAN tag.
  * When using VLANs the XenServer host handles all interpretation of the VLAN tags and strips the VLAN tags before routing packets to VMs.
  * If the XenServer host has one or more VLAN networks configured on an interface or bond, it will perform the VLAN tag/untag operations for all packets that enter/leave that interface/bond.
  * However, if no VLAN networks/bridges/whatever-the-term-may-be are configured on the interface/bond, then XenServer leaves 802.1q VLAN tags alone and passes the packets straight to the VM.
  * If there are **any** VLAN interfaces configured on top of the base interface (either a simple physical interface or a non-tagged bond), XenServer strips off the tags, as it is responsible for both tagging and untagging of packets on that base interface.
  * XenServer will leave 802.1q VLAN tags alone if there are no VLAN networks configured **on top of** your base interface, be that a single physical interface or a logical interface such as a bond.

===== Bonding =====

http://support.citrix.com/article/CTX137599

http://support.citrix.com/servlet/KbServlet/download/34969-102-704897/reference.pdf

Whenever possible, create NIC bonds as part of initial resource pool creation prior to joining additional hosts to the pool or creating VMs. Doing so allows the bond configuration to be automatically replicated to hosts as they are joined to the pool and reduces the number of steps required.

Adding a NIC bond to an existing pool requires **one** of the following:

  * Use the CLI to configure the bonds on the master and then each member of the pool.
  * Use the CLI to configure the bonds on the master and then restarting each member of the pool so that it inherits its settings from the pool master.
  * Use XenCenter to configure the bonds on the master. XenCenter automatically synchronizes the networking settings on the member servers with the master, so you do not need to reboot the member servers.

If you are not using XenCenter for NIC bonding, the quickest way to create pool-wide NIC bonds is to create the bond on the master, and then restart the other pool members. Alternatively, you can use the service xapi restart command. This causes the bond and VLAN settings on the master to be inherited by each host. The management interface of each host must, however, be manually reconfigured.

==== XenCenter ====

**Select Host -> NICs (tab) -> Create Bond**

==== CLI ====

<file>
xe network-list

xe network-create name-label="Pool-wide network associated with bond0"

xe pif-list

xe bond-create network-uuid=<UUID> pif-uuids=<PIF-UUID-1>,<PIF-UUID-2>

reboot
</file>

==== Storage ====

If you are using bonding for resiliency for your storage traffic, you may want to consider using LACP instead of the Linux bridge bonding. To use LACP bonding, you must configure the vSwitch as your networking stack. For more information, see Section 4.2, “vSwitch Networks”.
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