ID Allocator

Manage numeric ID allocation in NSO.

The NSO Resource Manager ID Allocator allocates integer numbers. These numbers can serve as various identifiers, such as VLAN IDs, either directly or through some mapping transformation.

Additional features:

• Supports odd and even parity for allocation, which produces an odd or even number, as requested.

Pool Definition

Each ID pool is a named configuration item under /resource-pools/id-pool and is defined by the range start and range end parameters. The two parameters specify the first and the last available value in the pool. The pool may consist of a single value, when the two parameters are the same.

admin@ncs(config)# resource-pools id-pool some-pool range start 1 end 1000
admin@ncs(config)# commit

Additionally, non-overlapping exclusion ranges may be defined for a pool. The values from the exclusion ranges are not available for allocation.

admin@ncs(config)# resource-pools id-pool some-pool exclude range 110 120
admin@ncs(config)# resource-pools id-pool some-pool exclude range 170 170
admin@ncs(config)# commit

resource-pools id-pool some-pool
 range start 100
 range end 199
 exclude 110 120
 exclude 170 170

Allocate Action

Manual allocation or pre-allocation is possible with the use of the /resource-pools/find-id action. If allocate parameter is specified, the allocation is persisted right away. Otherwise, a free resource is returned if found, however, it is not allocated.

admin@ncs# resource-pools find-id allocation-name my-value pool [ some-pool ]

See Allocation Options for more options.

Allocate by API

Python

For service use, Resource Manager exposes the resource_manager.service.Allocator class.

First, import and create an instance of the Allocator, supplying the service object as provided by the service callback (e.g. cb_create):

from resource_manager.service import Allocator

rm_allocator = Allocator(service)

Then, create a new ID allocator request by calling Allocator.id():

my_value_request = rm_allocator.id()

If you wish to allocate a specific value (if it is still available), you need to call the id() function with the request_id parameter instead:

my_value_request = rm_allocator.id(request_id=5)

You must also select at least one resource pool to assign the value from:

my_value_request = rm_allocator.id().pool('some-pool')
# or
my_value_request = rm_allocator.id().pool(['some-pool'])

You can further configure the request using a fluent interface, e.g.:

my_value_request = my_value_request.even()

Finally, allocate an actual value by calling allocate() with the allocation name:

my_value = my_value_request.allocate('my-value') # Returns e.g. 5

Java

Odd/Even Allocation

ID Allocator supports an additional parity allocation option that ensures the assigned value is odd or even. This feature caters to environments that require greater control of the ID assignment.

To enable this functionality, provide the parity odd or parity even option to the find-id action, or select the odd() or even() function when creating a request programmatically. For example:

odd_value = rm_allocator.id().pool("some-pool").odd().allocate("my-odd")

This type of allocation also supports additional alarms in case pool resources are running low (if alarms are enabled for the pool):

• id-pool-odd-exhausted and id-pool-even-exhausted: Raised when no more odd or even resources are available in the pool.

• id-pool-odd-low-threshold-reached and id-pool-even-low-threshold-reached: Raised when available odd or even resources fall below configured percentage.

The low threshold percentage can be configured per resource pool, under alarms.

resource-pools id-pool some-pool
 range start 100
 range end 199
 alarms low-threshold-odd-alarm 20
 alarms low-threshold-even-alarm 20