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 Plug-in specific extensions

Each vendor can choose to implement additional API extensions to the core API. This section describes the extensions for each plug-in.

 VMware NSX extensions

These sections explain NSX plug-in extensions.

 VMware NSX QoS extension

The VMware NSX QoS extension rate-limits network ports to guarantee a specific amount of bandwidth for each port. This extension, by default, is only accessible by a tenant with an admin role but is configurable through the policy.json file. To use this extension, create a queue and specify the min/max bandwidth rates (kbps) and optionally set the QoS Marking and DSCP value (if your network fabric uses these values to make forwarding decisions). Once created, you can associate a queue with a network. Then, when ports are created on that network they are automatically created and associated with the specific queue size that was associated with the network. Because one size queue for a every port on a network might not be optimal, a scaling factor from the nova flavor 'rxtx_factor' is passed in from Compute when creating the port to scale the queue.

Lastly, if you want to set a specific baseline QoS policy for the amount of bandwidth a single port can use (unless a network queue is specified with the network a port is created on) a default queue can be created in Networking which then causes ports created to be associated with a queue of that size times the rxtx scaling factor. Note that after a network or default queue is specified, queues are added to ports that are subsequently created but are not added to existing ports.

 VMware NSX QoS API abstractions
Table 7.16. VMware NSX QoS attributes
Attribute name Type Default Value Description
id uuid-str generated UUID for the QoS queue.
default Boolean False by default If True, ports are created with this queue size unless the network port is created or associated with a queue at port creation time.
name String None Name for QoS queue.
min Integer 0 Minimum Bandwidth Rate (kbps).
max Integer N/A Maximum Bandwidth Rate (kbps).
qos_marking String untrusted by default Whether QoS marking should be trusted or untrusted.
dscp Integer 0 DSCP Marking value.
tenant_id uuid-str N/A The owner of the QoS queue.
 Basic VMware NSX QoS operations

This table shows example neutron commands that enable you to complete basic queue operations:

Table 7.17. Basic VMware NSX QoS operations
Operation Command

Creates QoS queue (admin-only).

$ neutron queue-create --min 10 --max 1000 myqueue

Associates a queue with a network.

$ neutron net-create network --queue_id QUEUE_ID

Creates a default system queue.

$ neutron queue-create --default True --min 10 --max 2000 default

Lists QoS queues.

$ neutron queue-list

Deletes a QoS queue.

$ neutron queue-delete QUEUE_ID_OR_NAME'
 VMware NSX provider networks extension

Provider networks can be implemented in different ways by the underlying NSX platform.

The FLAT and VLAN network types use bridged transport connectors. These network types enable the attachment of large number of ports. To handle the increased scale, the NSX plug-in can back a single OpenStack Network with a chain of NSX logical switches. You can specify the maximum number of ports on each logical switch in this chain on the max_lp_per_bridged_ls parameter, which has a default value of 5,000.

The recommended value for this parameter varies with the NSX version running in the back-end, as shown in the following table.

Table 7.18. Recommended values for max_lp_per_bridged_ls
NSX version Recommended Value
2.x 64
3.0.x 5,000
3.1.x 5,000
3.2.x 10,000

In addition to these network types, the NSX plug-in also supports a special l3_ext network type, which maps external networks to specific NSX gateway services as discussed in the next section.

 VMware NSX L3 extension

NSX exposes its L3 capabilities through gateway services which are usually configured out of band from OpenStack. To use NSX with L3 capabilities, first create an L3 gateway service in the NSX Manager. Next, in /etc/neutron/plugins/vmware/nsx.ini set default_l3_gw_service_uuid to this value. By default, routers are mapped to this gateway service.

 VMware NSX L3 extension operations

Create external network and map it to a specific NSX gateway service:

$ neutron net-create public --router:external True --provider:network_type l3_ext \
--provider:physical_network L3_GATEWAY_SERVICE_UUID

Terminate traffic on a specific VLAN from a NSX gateway service:

$ neutron net-create public --router:external True --provider:network_type l3_ext \
--provider:physical_network L3_GATEWAY_SERVICE_UUID --provider:segmentation_id VLAN_ID
 Operational status synchronization in the VMware NSX plug-in

Starting with the Havana release, the VMware NSX plug-in provides an asynchronous mechanism for retrieving the operational status for neutron resources from the NSX back-end; this applies to network, port and router resources.

The back-end is polled periodically and the status for every resource is retrieved; then the status in the Networking database is updated only for the resources for which a status change occurred. As operational status is now retrieved asynchronously, performance for GET operations is consistently improved.

Data to retrieve from the back-end are divided in chunks in order to avoid expensive API requests; this is achieved leveraging NSX APIs response paging capabilities. The minimum chunk size can be specified using a configuration option; the actual chunk size is then determined dynamically according to: total number of resources to retrieve, interval between two synchronization task runs, minimum delay between two subsequent requests to the NSX back-end.

The operational status synchronization can be tuned or disabled using the configuration options reported in this table; it is however worth noting that the default values work fine in most cases.

Table 7.19. Configuration options for tuning operational status synchronization in the NSX plug-in
Option name Group Default value Type and constraints Notes
state_sync_interval nsx_sync 120 seconds Integer; no constraint. Interval in seconds between two run of the synchronization task. If the synchronization task takes more than state_sync_interval seconds to execute, a new instance of the task is started as soon as the other is completed. Setting the value for this option to 0 will disable the synchronization task.
max_random_sync_delay nsx_sync 0 seconds Integer. Must not exceed min_sync_req_delay When different from zero, a random delay between 0 and max_random_sync_delay will be added before processing the next chunk.
min_sync_req_delay nsx_sync 10 seconds Integer. Must not exceed state_sync_interval. The value of this option can be tuned according to the observed load on the NSX controllers. Lower values will result in faster synchronization, but might increase the load on the controller cluster.
min_chunk_size nsx_sync 500 resources Integer; no constraint. Minimum number of resources to retrieve from the back-end for each synchronization chunk. The expected number of synchronization chunks is given by the ratio between state_sync_interval and min_sync_req_delay. This size of a chunk might increase if the total number of resources is such that more than min_chunk_size resources must be fetched in one chunk with the current number of chunks.
always_read_status nsx_sync False Boolean; no constraint. When this option is enabled, the operational status will always be retrieved from the NSX back-end ad every GET request. In this case it is advisable to disable the synchronization task.

When running multiple OpenStack Networking server instances, the status synchronization task should not run on every node; doing so sends unnecessary traffic to the NSX back-end and performs unnecessary DB operations. Set the state_sync_interval configuration option to a non-zero value exclusively on a node designated for back-end status synchronization.

The fields=status parameter in Networking API requests always triggers an explicit query to the NSX back end, even when you enable asynchronous state synchronization. For example, GET /v2.0/networks/NET_ID?fields=status&fields=name.

 Big Switch plug-in extensions

This section explains the Big Switch neutron plug-in-specific extension.

 Big Switch router rules

Big Switch allows router rules to be added to each tenant router. These rules can be used to enforce routing policies such as denying traffic between subnets or traffic to external networks. By enforcing these at the router level, network segmentation policies can be enforced across many VMs that have differing security groups.

 Router rule attributes

Each tenant router has a set of router rules associated with it. Each router rule has the attributes in this table. Router rules and their attributes can be set using the neutron router-update command, through the horizon interface or the Networking API.

Table 7.20. Big Switch Router rule attributes
Attribute name Required Input Type Description
source Yes A valid CIDR or one of the keywords 'any' or 'external' The network that a packet's source IP must match for the rule to be applied
destination Yes A valid CIDR or one of the keywords 'any' or 'external' The network that a packet's destination IP must match for the rule to be applied
action Yes 'permit' or 'deny' Determines whether or not the matched packets will allowed to cross the router
nexthop No A plus-separated (+) list of next-hop IP addresses. For example, Overrides the default virtual router used to handle traffic for packets that match the rule
 Order of rule processing

The order of router rules has no effect. Overlapping rules are evaluated using longest prefix matching on the source and destination fields. The source field is matched first so it always takes higher precedence over the destination field. In other words, longest prefix matching is used on the destination field only if there are multiple matching rules with the same source.

 Big Switch router rules operations

Router rules are configured with a router update operation in OpenStack Networking. The update overrides any previous rules so all rules must be provided at the same time.

Update a router with rules to permit traffic by default but block traffic from external networks to the subnet:

$ neutron router-update ROUTER_UUID --router_rules type=dict list=true\
source=any,destination=any,action=permit \

Specify alternate next-hop addresses for a specific subnet:

$ neutron router-update ROUTER_UUID --router_rules type=dict list=true\
source=any,destination=any,action=permit \

Block traffic between two subnets while allowing everything else:

$ neutron router-update ROUTER_UUID --router_rules type=dict list=true\
source=any,destination=any,action=permit \
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