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Obsolete:ConfigureOpenvswitch

Revision as of 21:39, 28 August 2012 by Rkukura (talk)

Configuring the Quantum openvswitch Plugin

Support for provider networks being added via https://review.openstack.org/#/c/11388/ significantly changes the configuration of the Quantum openvswitch plugin. In addition to supporting the provider extension (see https://blueprints.launchpad.net/quantum/+spec/provider-networks), the openvswitch plugin now also can use multiple physical networks for VLAN tenant networks. This page is intended to provide guidance for testing and using this plugin until the admin guide and content on openvswitch.org has been updated.

Terminology

A number of terms will be used with very specific meanings:

  • virtual network - A Quantum L2 network (identified by a UUID and optional name) whose ports can be attached as vNICS to Nova instances and to various Quantum agents. The openvswitch plugin supports several different mechanisms to realize virtual networks.
  • physical network - A network connecting virtualization hosts (Nova compute nodes) and other network resources. Each physical network may support multiple virtual networks. The provider extension and the openvswitch plugin configuration identify physical networks using names.
  • tenant network - A "normal" virtual network created by/for a tenant. The tenant is not aware of how that network is physically realized.
  • provider network - A virtual network administratively created to map to a specific physical network in the data center, typically to enable direct access to non-OpenStack resources on that network. Tenants can be given access to provider networks.
  • VLAN network - A virtual network realized as packets on a specific physical network containing IEEE 802.1Q headers with a specific VID field value. VLAN networks sharing the same physical network are isolated from each other at L2, and can even have overlapping IP address spaces. Each distinct physical network is assumed to be a separate VLAN trunk, with a distinct space of VID values. Valid VID values are 1 through 4094.
  • flat network - A virtual network realized as packets on a specific physical network containing no IEEE 802.1Q header.
  • GRE tunnel - A virtual network realized as packets encapsulated using GRE. GRE tunnel packets are routed by the compute node hosts, so GRE tunnels are not associated by the openvswitch plugin with specific physical networks.

Provider Extension

The openvswitch plugin supports the provider extension. This means users of the quantum client with administrative privileges will see additional provider attributes on all virtual networks, and will be able to specify these attributes in order to create provider networks.

Provider Attributes

  • provider:network_type - Specifies the physical mechanism by which the virtual network is realized. Possible values with the openvswitch plugin are "flat", "vlan", and "gre", corresponding to flat networks, VLAN networks, and GRE tunnels as defined above. Note that "flat" and "vlan" type provider networks can be created with administrative privileges, while tenant networks can be realized as either "vlan" or "gre" network types.
  • provider:physical_network - Specifies the name of the physical network over which the virtual network is realized for flat and VLAN networks. It is not applicable to the "gre" network type because GRE tunnels are routed according the the host's routing table rather than over a specific physical network.
  • provider:vlan_id - For VLAN networks, specifies the VLAN VID on the physical network that realizes the virtual network. Note that each physical network has a separate independent space of VIDs, so more than 4094 VLAN virtual networks can be supported by using multiple physical networks.

Provider CLI Examples

TBD

Openvswitch Plugin and Agent Configuration

Configuring the openvswitch plugin and agent involves setting configuration variables used by the plugin on the Quantum server node and by the openvswitch agent on all the nodes on which it runs, as well as configuring OVS bridges on the nodes where the openvswitch agent runs.

Configuration Variables

The openvswitch plugin and agent are configured by editing the file typically installed as /etc/quantum/plugins/openvswitch/ovs_quantum_plugin.ini. The following configuration variables are relevant:

  • OVS.integration_bridge - default: "br-int" - Specifies the name of the OVS integration bridge used by the agent for all virtual networks.
  • OVS.tunnel_bridge - default: "br-tun" - Specifies the name of the OVS tunnel bridge used by the agent for GRE tunnels.
  • OVS.local_ip - default: "10.0.0.3" - Specifies the IP address for the local endpoint on which GRE tunnel packets are received by the agent.
  • OVS.bridge_mappings - default: "default:br-eth1" - List of <physical_network>:<bridge> tuples, each specifying the OVS bridge used by the agent for a physical network to which it is connected.
  • OVS.network_vlan_ranges - default: "default:2000:3999" - List of <physical_network>:<vlan_min>:<vlan_max> or <physical_network> tuples on the server, each specifying the name of an available physical network and, optionally, a range of VIDs on that network available for allocation to tenant networks. All physical networks available for provider network creation must be listed at least once, even if no tenant networks will be allocated on that physical network. A physical network can be listed multiple times to make multiple ranges of VIDs on that physical network available for tenant network creation.
  • OVS.tunnel_id_ranges - default: "" - List of <tun_min>:<tun_max> tuples on the server, each specifying a range of tunnel IDs available for tenant network creation.
  • DATABASE.sql_connection - default: "sqlite://" - URL for database connection used by the plugin, and if AGENT.rpc is false, also by the agent.
  • DATABASE.sql_max_retries - default: -1 -
  • DATABASE.reconnect_interval - default: 2 -
  • AGENT.polling_interval - default: 2 -
  • AGENT.root_helper - default: "sudo" -
  • AGENT.log_file - default: None -
  • AGENT.rpc - default: True - Specifies whether the agent uses the RPC mechanism to communicate with the plugin. If False, the agent connects via the database instead.

The RPC, logging, and notification configuration variables defined in /etc/quantum/quantum.conf also apply to the plugin, and the RPC and logging variables apply to the agent.

The physical_network names and bridge names in the above variable should not contain embedded spaces.

Tenant Network Pool Configuration

The openvswitch plugin supports realizing tenant networks as either VLAN networks or GRE tunnels. Each mechanism allows configuration in the server of a pool of physical resources available for allocation to tenant networks. If pools for both mechanisms are configured, when a new tenant network is created, a VLAN network will be used if one is available, and if not, a GRE tunnel will be used. If no pools are configured, or if the supply is exhausted, no new tenant networks can be created, but it still may be possible to create provider networks.

To configure a pool of VLANs that can be allocated as tenant networks, use the OVS.network_vlan_ranges configuration variable in the server: 


[OVS]
network_vlan_ranges = physnet1:1:4094,physnet2:1000:1999,physnet2:3000:3999


The above example makes VIDs 1 through 4094 on the physical network named "physnet1" available for tenant networks, along with VIDs 1000 through 1999 and 3000 through 3999 on the physical network named "physnet2".

Since VLANs on a physical network named "default" are specified in the default value of OVS.network_vlan_ranges, override it to disable the pool of VLANs for tenant networks: 


[OVS]
network_vlan_ranges =


To configure a pool of GRE tunnels that can be allocated as tenant networks, use the OVS.tunnel_id_ranges configuration variable in the server: 


[OVS]
tunnel_id_ranges = 0:999,2000:2999


This example makes tunnel IDs 0 through 999 and 2000 through 2999 available for allocation. Note that, unlike VIDs, tunnel IDs are not specific to a physical network.

The allocation states of the items in each pool are maintained in the openvswitch plugin's database. Each time the quantum server starts, the plugin synchronizes the contents of the database with the current values for the configuration variables. If the configuration variable changes, items may be added to the pool, and unused items may be removed. If a VLAN or tunnel currently allocated to a network is no longer in the specified range, it will continue to be used until the network is deleted, but will not be returned to the pool on deletion.

Provider Network Configuration

When creating a provider network using the provider extension API as described above, the openvswitch plugin validates that the supplied provider:physical_network value is the name of a known physical network. The set of known physical networks is configured on the server using the OVS.network_vlan_ranges variable. Any physical networks for which tenant network VLAN ranges are specified are also available for provider networks. Physical networks can also be made available without ranges of VLANs for tenant networks. 


[OVS]
network_vlan_ranges = physnet1:1:4094,physnet2,physnet3:3000:3999


In this example, the physical networks named "physnet1", "physnet2", and "physnet3" are all available for allocation of flat or VLAN provider networks.

Agent Integration Bridge Configuration

A well-known OVS integration bridge connects entities such Nova instance vNICs and the Quantum DHCP and L3 agents with virtual networks. The name of this bridge can be configured using the OVS.integration_bridge variable, but overriding the default value of "br-int" is not recommended as all entities need to agree on the bridge name.

The integration bridge must be administratively created before first running the quantum agent: 


sudo ovs-vsctl add-br br-int


Note that OVS bridges are persistent, so this only needs to be created once.

Agent Tunneling Configuration

If GRE tunnels are used for tenant networks, each agent must be configured with the local IP address for its tunnel endpoint: 


[OVS]
local_ip = 10.1.2.3


An OVS bridge is used for GRE tunnels, and its name can be configured via the OVS.tunnel_bridge variable. The default value of "br-tun" should be fine for most deployments. This bridge is created automatically by the openvswitch agent, and should not be accessed by any other entities.

Agent Physical Network Bridge Configuration

TBD

Complete Examples

TBD

Using Devstack

TBD

Known Limitations and Issues

  • GRE tunneling with the openvswitch plugin requires OVS kernel modules that not part of the Linux kernel source tree. These modules are not available in certain Linux distributions, including Fedora, so tunneling must not be configured on these systems.

Possible Enhancements

TBD

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