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oopt-gnpy/gnpy/topology/spectrum_assignment.py
EstherLerouzic 7a1b15a916 chore: make sure all python files have the correct header 
Signed-off-by: EstherLerouzic <esther.lerouzic@orange.com>
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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# SPDX-License-Identifier: BSD-3-Clause
# gnpy.topology.spectrum_assignment: spectrum assignment functionality
# Copyright (C) 2025 Telecom Infra Project and GNPy contributors
# see AUTHORS.rst for a list of contributors
"""
gnpy.topology.spectrum_assignment
=================================
This module contains the :class:`Oms` and :class:`Bitmap` classes and methods to
select and assign spectrum. The :func:`spectrum_selection` function identifies the free
slots and :func:`select_candidate` selects the candidate spectrum according to
strategy: for example first fit
oms records its elements, and elements are updated with an oms to have
element/oms correspondace
"""
from collections import namedtuple
from logging import getLogger
from gnpy.core.elements import Roadm, Transceiver, Edfa, Multiband_amplifier
from gnpy.core.exceptions import ServiceError, SpectrumError
from gnpy.core.utils import order_slots, restore_order
from gnpy.topology.request import compute_spectrum_slot_vs_bandwidth, find_elements_common_range
LOGGER = getLogger(__name__)
GUARDBAND = 25e9
class Bitmap:
"""records the spectrum occupation"""
def __init__(self, f_min, f_max, grid, guardband=GUARDBAND, bitmap=None):
# n is the min index including guardband. Guardband is required to be sure
# that a channel can be assigned with center frequency fmin (means that its
# slot occupation goes below freq_index_min
n_min = frequency_to_n(f_min, grid)
n_max = frequency_to_n(f_max, grid)
self.n_min = n_min
self.n_max = n_max
self.freq_index_min = frequency_to_n(f_min + guardband)
self.freq_index_max = frequency_to_n(f_max - guardband)
self.freq_index = list(range(n_min, n_max + 1))
self.guardband = guardband
if bitmap is None:
self.bitmap = [1] * (n_max - n_min + 1)
elif len(bitmap) == len(self.freq_index):
self.bitmap = bitmap
else:
raise SpectrumError(f'bitmap is not consistant with f_min{f_min} - n: {n_min} and f_max{f_max}- n :{n_max}')
def getn(self, i):
"""converts the n (itu grid) into a local index"""
return self.freq_index[i]
def geti(self, nvalue):
"""converts the local index into n (itu grid)"""
return self.freq_index.index(nvalue)
def insert_left(self, newbitmap):
"""insert bitmap on the left to align oms bitmaps if their start frequencies are different"""
self.bitmap = newbitmap + self.bitmap
temp = list(range(self.n_min - len(newbitmap), self.n_min))
self.freq_index = temp + self.freq_index
self.n_min = self.freq_index[0]
def insert_right(self, newbitmap):
"""insert bitmap on the right to align oms bitmaps if their stop frequencies are different"""
self.bitmap = self.bitmap + newbitmap
self.freq_index = self.freq_index + list(range(self.n_max, self.n_max + len(newbitmap)))
self.n_max = self.freq_index[-1]
# +'grid available_slots f_min f_max services_list')
OMSParams = namedtuple('OMSParams', 'oms_id el_id_list el_list')
class OMS:
"""OMS class is the logical container that represent a link between two adjacent ROADMs and
records the crossed elements and the occupied spectrum
"""
def __init__(self, *args, **params):
params = OMSParams(**params)
self.oms_id = params.oms_id
self.el_id_list = params.el_id_list
self.el_list = params.el_list
self.spectrum_bitmap = []
self.nb_channels = 0
self.service_list = []
def __str__(self):
return '\n\t'.join([f'{type(self).__name__} {self.oms_id}',
f'{self.el_id_list[0]} - {self.el_id_list[-1]}'])
def __repr__(self):
return '\n\t'.join([f'{type(self).__name__} {self.oms_id}',
f'{self.el_id_list[0]} - {self.el_id_list[-1]}', '\n'])
def add_element(self, elem):
"""records oms elements"""
self.el_id_list.append(elem.uid)
self.el_list.append(elem)
def update_spectrum(self, f_min, f_max, guardband=GUARDBAND, existing_spectrum=None, grid=0.00625e12):
"""Frequencies expressed in Hz.
Add 150 GHz margin to enable a center channel on f_min
Use ITU-T G694.1 Flexible DWDM grid definition
For the flexible DWDM grid, the allowed frequency slots have a nominal central frequency (in THz) defined by:
193.1 + n × 0.00625 where n is a positive or negative integer including 0
and 0.00625 is the nominal central frequency granularity in THz
and a slot width defined by:
12.5 × m where m is a positive integer and 12.5 is the slot width granularity in GHz.
Any combination of frequency slots is allowed as long as no two frequency slots overlap.
If bitmap is not None, then use it: Bitmap checks its consistency with f_min f_max
else a brand new bitmap is created
"""
self.spectrum_bitmap = Bitmap(f_min=f_min, f_max=f_max, grid=grid, guardband=guardband,
bitmap=existing_spectrum)
def assign_spectrum(self, nvalue, mvalue):
"""change oms spectrum to mark spectrum assigned"""
if not isinstance(nvalue, int):
raise SpectrumError(f'N must be a signed integer, got {nvalue}')
if not isinstance(mvalue, int):
raise SpectrumError(f'M must be an integer, got {mvalue}')
if mvalue <= 0:
raise SpectrumError(f'M must be positive, got {mvalue}')
if nvalue > self.spectrum_bitmap.freq_index_max:
raise SpectrumError(f'N {nvalue} over the upper spectrum boundary')
if nvalue < self.spectrum_bitmap.freq_index_min:
raise SpectrumError(f'N {nvalue} below the lower spectrum boundary')
startn, stopn = mvalue_to_slots(nvalue, mvalue)
if stopn > self.spectrum_bitmap.n_max:
raise SpectrumError(f'N {nvalue}, M {mvalue} over the N spectrum bitmap bounds')
if startn <= self.spectrum_bitmap.n_min:
raise SpectrumError(f'N {nvalue}, M {mvalue} below the N spectrum bitmap bounds')
self.spectrum_bitmap.bitmap[self.spectrum_bitmap.geti(startn):self.spectrum_bitmap.geti(stopn) + 1] = [0] * (stopn - startn + 1)
def add_service(self, service_id, nb_wl):
"""record service and mark spectrum as occupied"""
self.service_list.append(service_id)
self.nb_channels += nb_wl
def frequency_to_n(freq, grid=0.00625e12):
"""converts frequency into the n value (ITU grid)
reference to Recommendation G.694.1 (02/12), Figure I.3
https://www.itu.int/rec/T-REC-G.694.1-201202-I/en
>>> frequency_to_n(193.1375e12)
6
>>> frequency_to_n(193.225e12)
20
"""
return (int)((freq - 193.1e12) / grid)
def nvalue_to_frequency(nvalue, grid=0.00625e12):
"""converts n value into a frequency
reference to Recommendation G.694.1 (02/12), Table 1
https://www.itu.int/rec/T-REC-G.694.1-201202-I/en
>>> nvalue_to_frequency(6)
193137500000000.0
>>> nvalue_to_frequency(-1, 0.1e12)
193000000000000.0
"""
return 193.1e12 + nvalue * grid
def mvalue_to_slots(nvalue, mvalue):
"""convert center n an m into start and stop n"""
startn = nvalue - mvalue
stopn = nvalue + mvalue - 1
return startn, stopn
def slots_to_m(startn, stopn):
"""converts the start and stop n values to the center n and m value
reference to Recommendation G.694.1 (02/12), Figure I.3
https://www.itu.int/rec/T-REC-G.694.1-201202-I/en
>>> nval, mval = slots_to_m(6, 20)
>>> nval
13
>>> mval
7
"""
nvalue = (int)((startn + stopn + 1) / 2)
mvalue = (int)((stopn - startn + 1) / 2)
return nvalue, mvalue
def m_to_freq(nvalue, mvalue, grid=0.00625e12):
"""converts m into frequency range
spectrum(13,7) is (193137500000000.0, 193225000000000.0)
reference to Recommendation G.694.1 (02/12), Figure I.3
https://www.itu.int/rec/T-REC-G.694.1-201202-I/en
>>> fstart, fstop = m_to_freq(13, 7)
>>> fstart
193137500000000.0
>>> fstop
193225000000000.0
"""
startn, stopn = mvalue_to_slots(nvalue, mvalue)
fstart = nvalue_to_frequency(startn, grid)
fstop = nvalue_to_frequency(stopn + 1, grid)
return fstart, fstop
def align_grids(oms_list):
"""Used to apply same grid to all oms : same starting n, stop n and slot size. Out of grid slots are set to 0."""
n_min = min([o.spectrum_bitmap.n_min for o in oms_list])
n_max = max([o.spectrum_bitmap.n_max for o in oms_list])
for this_o in oms_list:
if (this_o.spectrum_bitmap.n_min - n_min) > 0:
this_o.spectrum_bitmap.insert_left([0] * (this_o.spectrum_bitmap.n_min - n_min))
if (n_max - this_o.spectrum_bitmap.n_max) > 0:
this_o.spectrum_bitmap.insert_right([0] * (n_max - this_o.spectrum_bitmap.n_max))
return oms_list
def find_network_freq_range(network, equipment):
"""Find the lowest freq from amps and highest freq among all amps to determine the resulting bitmap
"""
amp_bands = [band for n in network.nodes() if isinstance(n, (Edfa, Multiband_amplifier)) for band in n.params.bands]
min_frequencies = [a['f_min'] for a in amp_bands]
max_frequencies = [a['f_max'] for a in amp_bands]
return min(min_frequencies), max(max_frequencies)
def create_oms_bitmap(oms, equipment, f_min, f_max, guardband, grid):
"""Find the highest low freq from oms amps and lowest high freq among oms amps to determine
the possible bitmap window.
f_min and f_max represent the useable spectrum (not the useable center frequencies)
ie n smaller than frequency_to_n(min_freq, grid) are not useable
"""
n_min = frequency_to_n(f_min, grid)
n_max = frequency_to_n(f_max, grid) - 1
common_range = find_elements_common_range(oms.el_list, equipment)
band0 = common_range[0]
band0_n_min = frequency_to_n(band0['f_min'], grid)
band0_n_max = frequency_to_n(band0['f_max'], grid)
bitmap = [0] * (band0_n_min - n_min) + [1] * (band0_n_max - band0_n_min + 1)
i = 1
while i < len(common_range):
band = common_range[i]
band_n_min = frequency_to_n(band['f_min'], grid)
band_n_max = frequency_to_n(band['f_max'], grid)
bitmap = bitmap + [0] * (band_n_min - band0_n_max - 1) + [1] * (band_n_max - band_n_min + 1)
band0_n_max = band_n_max
i += 1
bitmap = bitmap + [0] * (n_max - band0_n_max)
return bitmap
def build_oms_list(network, equipment):
"""initialization of OMS list in the network
an oms is build reading all intermediate nodes between two adjacent ROADMs
each element within the list is being added an oms and oms_id to record the
oms it belongs to.
the function supports different spectrum width and supposes that the whole network
works with the min range among OMSs
"""
oms_id = 0
oms_list = []
# identify all vertices of OMS: of course ROADM, but aso links to external chassis transponders
oms_vertices = [n for n in network.nodes() if isinstance(n, Roadm)] +\
[n for n in network.nodes() if isinstance(n, Transceiver)
and not isinstance(next(network.successors(n)), Roadm)]
# determine the size of the bitmap common to all the omses: find min and max frequencies of all amps
# in the network. These gives the band not the center frequency. Thhen we use a reference channel
# slot width (50GHz) to set the f_min, f_max
f_min, f_max = find_network_freq_range(network, equipment)
for node in oms_vertices:
for edge in network.edges([node]):
if not isinstance(edge[1], Transceiver):
nd_in = edge[0] # nd_in is a Roadm
try:
nd_in.oms_list.append(oms_id)
except AttributeError:
nd_in.oms_list = []
nd_in.oms_list.append(oms_id)
nd_out = edge[1]
params = {}
params['oms_id'] = oms_id
params['el_id_list'] = []
params['el_list'] = []
oms = OMS(**params)
oms.add_element(nd_in)
while not isinstance(nd_out, Roadm):
oms.add_element(nd_out)
# add an oms_id in the element
nd_out.oms_id = oms_id
nd_out.oms = oms
n_temp = nd_out
nd_out = next(n[1] for n in network.edges([n_temp]) if n[1].uid != nd_in.uid)
nd_in = n_temp
oms.add_element(nd_out)
# nd_out is a Roadm
try:
nd_out.oms_list.append(oms_id)
except AttributeError:
nd_out.oms_list = []
nd_out.oms_list.append(oms_id)
bitmap = create_oms_bitmap(oms, equipment, f_min=f_min, f_max=f_max, guardband=GUARDBAND,
grid=0.00625e12)
oms.update_spectrum(f_min, f_max, guardband=GUARDBAND, grid=0.00625e12, existing_spectrum=bitmap)
# oms.assign_spectrum(13,7) gives back (193137500000000.0, 193225000000000.0)
# as in the example in the standard
# oms.assign_spectrum(13,7)
oms_list.append(oms)
oms_id += 1
oms_list = align_grids(oms_list)
reversed_oms(oms_list)
return oms_list
def reversed_oms(oms_list):
"""identifies reversed OMS
only applicable for non parallel OMS
"""
for oms in oms_list:
has_reversed = False
for this_o in oms_list:
if (oms.el_id_list[0] == this_o.el_id_list[-1] and
oms.el_id_list[-1] == this_o.el_id_list[0]):
oms.reversed_oms = this_o
has_reversed = True
break
if not has_reversed:
oms.reversed_oms = None
def bitmap_sum(band1, band2):
"""mark occupied bitmap by 0 if the slot is occupied in band1 or in band2"""
res = []
for i, elem in enumerate(band1):
if band2[i] * elem == 0:
res.append(0)
else:
res.append(1)
return res
def build_path_oms_id_list(pth):
path_oms = []
for elem in pth:
if not isinstance(elem, Roadm) and not isinstance(elem, Transceiver):
# only edfa, fused and fibers have oms_id attribute
path_oms.append(elem.oms_id)
# remove duplicate oms_id, order is not important
return list(set(path_oms))
def aggregate_oms_bitmap(path_oms, oms_list):
spectrum = oms_list[path_oms[0]].spectrum_bitmap
bitmap = spectrum.bitmap
# assuming all oms have same freq indices
for oms in path_oms[1:]:
bitmap = bitmap_sum(oms_list[oms].spectrum_bitmap.bitmap, bitmap)
params = {
'oms_id': 0,
'el_id_list': 0,
'el_list': []
}
freq_min = nvalue_to_frequency(spectrum.n_min)
freq_max = nvalue_to_frequency(spectrum.n_max)
aggregate_oms = OMS(**params)
aggregate_oms.update_spectrum(freq_min, freq_max, grid=0.00625e12, guardband=spectrum.guardband,
existing_spectrum=bitmap)
return aggregate_oms
def spectrum_selection(test_oms, requested_m, requested_n=None):
"""Collects spectrum availability and call the select_candidate function"""
freq_index = test_oms.spectrum_bitmap.freq_index
freq_index_min = test_oms.spectrum_bitmap.freq_index_min
freq_index_max = test_oms.spectrum_bitmap.freq_index_max
freq_availability = test_oms.spectrum_bitmap.bitmap
if requested_n is None:
# avoid slots reserved on the edge 0.15e-12 on both sides -> 24
candidates = [(freq_index[i] + requested_m, freq_index[i], freq_index[i] + 2 * requested_m - 1)
for i in range(len(freq_availability))
if freq_availability[i:i + 2 * requested_m] == [1] * (2 * requested_m)
and freq_index[i] >= freq_index_min
and freq_index[i + 2 * requested_m - 1] <= freq_index_max]
candidate = select_candidate(candidates, policy='first_fit')
else:
i = test_oms.spectrum_bitmap.geti(requested_n)
if (freq_availability[i - requested_m:i + requested_m] == [1] * (2 * requested_m)
and freq_index[i - requested_m] >= freq_index_min
and freq_index[i + requested_m - 1] <= freq_index_max):
# candidate is the triplet center_n, startn and stopn
candidate = (requested_n, requested_n - requested_m, requested_n + requested_m - 1)
else:
candidate = (None, None, None)
return candidate
def determine_slot_numbers(test_oms, requested_n, required_m, per_channel_m):
"""determines max availability around requested_n. requested_n should not be None"""
bitmap = test_oms.spectrum_bitmap
freq_index = bitmap.freq_index
freq_index_min = bitmap.freq_index_min
freq_index_max = bitmap.freq_index_max
freq_availability = bitmap.bitmap
center_i = bitmap.geti(requested_n)
i = per_channel_m
while (freq_availability[center_i - i:center_i + i] == [1] * (2 * i)
and freq_index[center_i - i] >= freq_index_min
and freq_index[center_i + i - 1] <= freq_index_max
and i <= required_m):
i += per_channel_m
return i - per_channel_m
def select_candidate(candidates, policy):
"""selects a candidate among all available spectrum"""
if policy == 'first_fit':
if candidates:
return candidates[0]
else:
return (None, None, None)
else:
raise ServiceError('Only first_fit spectrum assignment policy is implemented.')
def compute_n_m(required_m, rq, path_oms, oms_list, per_channel_m, policy='first_fit'):
""" based on requested path_bandwidth fill in M=None values with uint values, using per_channel_m
and center frequency, with first fit strategy. The function checks the available spectrum but check
consistencies among M values of the request, but not with other requests.
For example, if request is for 32 slots corresponding to 8 x 4 slots of 32Gbauds channels,
the following frequency slots will result in the following assignment
N = 0, 8, 16, 32 -> 0, 8, 16, 32
M = 8, None, 8, None -> 8, 8, 8, 8
N = 0, 8, 16, 32 -> 0, , 16
M = None, None, 8, None -> 24, , 8
"""
selected_m = []
selected_n = []
remaining_slots_to_serve = required_m
# order slots for the computation: assign biggest m first
rq_N, rq_M, order = order_slots([{'N': n, 'M': m} for n, m in zip(rq.N, rq.M)])
# Create an oms that represents current assignments of all oms listed in path_oms, and test N and M on it.
# If M is defined, checks that proposed N, M is free
test_oms = aggregate_oms_bitmap(path_oms, oms_list)
for n, m in zip(rq_N, rq_M):
if m is not None and n is not None:
# check availabilityfor this n, m
available_slots = determine_slot_numbers(test_oms, n, m, m)
if available_slots == 0:
# if n, m are not feasible, break at this point no have non zero remaining_slots_to_serve
# in order to blocks the request (even is other N,M where feasible)
break
elif m is not None and n is None:
# find a candidate n
n, _, _ = spectrum_selection(test_oms, m, None)
if n is None:
# if no n is feasible for the m, block the request
break
elif m is None and n is not None:
# find a feasible m for this n. If None is found, then block the request
m = determine_slot_numbers(test_oms, n, remaining_slots_to_serve, per_channel_m)
if m == 0 or remaining_slots_to_serve == 0:
break
else:
# if n and m are not defined, try to find a single assignment to fits the remaining slots to serve
# (first fit strategy)
n, _, _ = spectrum_selection(test_oms, remaining_slots_to_serve, None)
if n is None or remaining_slots_to_serve == 0:
break
else:
m = remaining_slots_to_serve
selected_m.append(m)
selected_n.append(n)
test_oms.assign_spectrum(n, m)
remaining_slots_to_serve = remaining_slots_to_serve - m
# re-order selected_m and selected_n according to initial request N, M order, ignoring None values
not_selected = [None for i in range(len(rq_N) - len(selected_n))]
selected_m = restore_order(selected_m + not_selected, order)
selected_n = restore_order(selected_n + not_selected, order)
return selected_n, selected_m, remaining_slots_to_serve
def pth_assign_spectrum(pths, rqs, oms_list, rpths):
"""basic first fit assignment
if reversed path are provided, means that occupation is bidir
"""
for pth, rq, rpth in zip(pths, rqs, rpths):
if hasattr(rq, 'blocking_reason'):
rq.N = None
rq.M = None
else:
# computes the number of channels required for path_bandwidth and the min required nb of slots
# for one channel (corresponds to the spacing)
nb_wl, required_m = compute_spectrum_slot_vs_bandwidth(rq.path_bandwidth,
rq.spacing, rq.bit_rate)
_, per_channel_m = compute_spectrum_slot_vs_bandwidth(rq.bit_rate,
rq.spacing, rq.bit_rate)
# find oms ids that are concerned both by pth and rpth
path_oms = build_path_oms_id_list(pth + rpth)
if getattr(rq, 'M', None) is not None and all(rq.M):
# if all M are well defined: Consistency check that the requested M are enough to carry the nb_wl:
# check that the integer number of per_channel_m carried in each M value is enough to carry nb_wl.
# if not, blocks the demand
nb_channels_of_request = sum([m // per_channel_m for m in rq.M])
# TODO: elaborate a more accurate estimate with nb_wl * min_spacing + possibly guardbands in case of
# superchannel closed packing.
if nb_wl > nb_channels_of_request:
rq.N = None
rq.M = None
rq.blocking_reason = 'NOT_ENOUGH_RESERVED_SPECTRUM'
# need to stop here for this request and not go though spectrum selection process
continue
# Use the req.M even if nb_wl and required_m are smaller.
# first fit strategy: assign as many lambda as possible in the None remaining N, M values
selected_n, selected_m, remaining_slots_to_serve = \
compute_n_m(required_m, rq, path_oms, oms_list, per_channel_m)
# if there are some remaining_slots_to_serve, this means that provided rq.M and rq.N values were
# not possible. Then do not go though spectrum assignment process and blocks the demand
if remaining_slots_to_serve > 0:
rq.N = None
rq.M = None
rq.blocking_reason = 'NO_SPECTRUM'
continue
for oms_elem in path_oms:
for this_n, this_m in zip(selected_n, selected_m):
if this_m is not None:
oms_list[oms_elem].assign_spectrum(this_n, this_m)
oms_list[oms_elem].add_service(rq.request_id, nb_wl)
rq.N = selected_n
rq.M = selected_m
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