oopt-gnpy/gnpy/core/network.py

#!/usr/bin/env python3

'''
gnpy.core.network
=================

This module contains functions for constructing networks of network elements.
'''

from gnpy.core.convert import convert_file
from networkx import DiGraph
from logging import getLogger
from operator import itemgetter
from gnpy.core import elements
from gnpy.core.elements import Fiber, Edfa, Transceiver, Roadm, Fused
from gnpy.core.equipment import edfa_nf
from gnpy.core.units import UNITS
from gnpy.core.utils import load_json

logger = getLogger(__name__)

def load_network(filename, equipment):
    json_filename = ''
    if filename.suffix.lower() == '.xls':
        logger.info('Automatically generating topology JSON file')        
        json_filename = convert_file(filename)
    elif filename.suffix.lower() == '.json':
        json_filename = filename
    else:
        raise ValueError(f'unsuported topology filename extension {filename.suffix.lower()}')
    json_data = load_json(json_filename)
    return network_from_json(json_data, equipment)

def network_from_json(json_data, equipment):
    # NOTE|dutc: we could use the following, but it would tie our data format
    #            too closely to the graph library
    # from networkx import node_link_graph
    g = DiGraph()
    for el_config in json_data['elements']:
        typ = el_config.pop('type')
        variety = el_config.pop('type_variety', 'default')
        if typ in equipment and variety in equipment[typ]:
            extra_params = equipment[typ][variety]
            el_config.setdefault('params', {}).update(extra_params._asdict())
        cls = getattr(elements, typ)
        el = cls(**el_config)
        g.add_node(el)

    nodes = {k.uid: k for k in g.nodes()}

    for cx in json_data['connections']:
        from_node, to_node = cx['from_node'], cx['to_node']
        g.add_edge(nodes[from_node], nodes[to_node])

    return g

def select_edfa(ingress_span_loss, equipment):
    """amplifer selection algorithm
    @Orange Jean-Luc Augé
    """
    #TODO |jla add power requirement in the selection criteria
    TARGET_EXTENDED_GAIN = 2.1
    #MAX_EXTENDED_GAIN = 5
    edfa_dict = equipment['Edfa']
    edfa_list = [(edfa_variety, 
                edfa_dict[edfa_variety].gain_flatmax-ingress_span_loss,
                edfa_nf(ingress_span_loss, edfa_variety, equipment)) \
                for edfa_variety in edfa_dict]
    acceptable_edfa_list = list(filter(lambda x : x[1]>-TARGET_EXTENDED_GAIN, edfa_list))
    #print(acceptable_edfa_list)
    #print(ingress_span_loss)
    if len(acceptable_edfa_list) < 1: 
        #no amplifier satisfies the required gain, so pick the highest gain one:
        return max(edfa_list, key=itemgetter(1))[0]
    else:
        #chose the amp with the best NF among the acceptable ones:
        return min(acceptable_edfa_list, key=itemgetter(2))[0]

def set_roadm_loss(path_roadms, roadm_loss):
    for roadm in path_roadms:
        roadm.loss = roadm_loss

def set_edfa_dp(network, amps):
    prev_dp = 0
    for amp in amps:
        next_node = [n for n in network.successors(amp)][0]
        prev_node = [n for n in network.predecessors(amp)][0]
        prev_node_loss = span_loss(network, prev_node)
        if isinstance(next_node, Roadm): #ingress amp: set dp = 0
            dp = 0
        else:
            dp = prev_dp + amp.operational.gain_target - prev_node_loss
            #print('prev_node', prev_node, prev_node_loss)
            #print('amp',amp)
            #print('next node', next_node)
            #print('gain', amp.operational.gain_target)
            #print('edfa dp',prev_dp,dp)
        amp.dp_db = dp
        prev_dp = dp

def prev_fiber_node_generator(network, node):
    """fused spans interest:
    iterate over all predecessors while they are Fiber type"""
    prev_node = [n for n in network.predecessors(node)]
    if len(prev_node) == 1:
        #fibers or fused spans so there is only 1 predecessor
        if isinstance(prev_node[0], Fused) or isinstance(node, Fused):
            # yield and re-iterate
            yield prev_node[0]
            yield from prev_fiber_node_generator(network, prev_node[0])
        else:
            StopIteration

def span_loss(network, node):
    loss = node.loss if node.passive else 0
    return loss + sum(n.loss for n in prev_fiber_node_generator(network, node))

def add_egress_amplifier(network, node, equipment):
    if isinstance(node, Edfa):
        return

    next_nodes = [n for n in network.successors(node)
        if not (isinstance(n, Transceiver) or isinstance(n, Fused))]
        #no amplification for fused spans or TRX

    for i, next_node in enumerate(next_nodes):
        if isinstance(next_node, Edfa):
            if next_node.operational.gain_target == 0:
                total_loss = span_loss(network, node)
                next_node.operational.gain_target = total_loss
        else:
            network.remove_edge(node, next_node)
            total_loss = span_loss(network, node)
            edfa_variety = select_edfa(total_loss, equipment)
            extra_params = equipment['Edfa'][edfa_variety]
            amp = Edfa(
                        uid = f'Edfa{i}_{node.uid}',
                        params = extra_params._asdict(),
                        operational = {
                            'gain_target': total_loss,
                            'tilt_target': 0,
                        })            
            network.add_node(amp)
            network.add_edge(node,amp)
            network.add_edge(amp, next_node)


def calculate_new_length(fiber_length, bounds, target):
    if fiber_length < bounds.stop:
        return fiber_length, 1

    n_spans = int(fiber_length // target)

    length1 = fiber_length / (n_spans+1)
    delta1 = target-length1
    result1 = (length1, n_spans+1)

    length2 = fiber_length / n_spans
    delta2 = length2-target
    result2 = (length2, n_spans)

    if length1 in bounds and length2 not in bounds:
        result = result1
    elif length2 in bounds and length1 not in bounds:
        result = result2
    else:
        result = result1 if delta1 < delta2 else result2

    return result


def split_fiber(network, fiber, bounds, target, equipment):
    new_length, n_spans = calculate_new_length(fiber.length, bounds, target)
    if n_spans == 1:
        add_egress_amplifier(network, fiber, equipment)
        return

    next_node = [n for n in network.successors(fiber)][0]
    prev_node = [n for n in network.predecessors(fiber)][0]
    network.remove_edge(fiber, next_node)
    network.remove_edge(prev_node, fiber)
    new_spans = [
        Fiber(
            uid =      f'{fiber.uid}_({span}/{n_spans})',
            metadata = fiber.metadata,
            params = fiber.params._asdict()
        ) for span in range(n_spans)
    ]
    for new_span in new_spans:
        network.add_node(new_span)
        network.add_edge(prev_node, new_span)
        add_egress_amplifier(network, new_span, equipment)
        prev_node = new_span
    network.add_edge(prev_node, next_node)

def build_network(network, equipment, bounds=range(75_000, 150_000), target=100_000):
    fibers = [f for f in network.nodes() if isinstance(f, Fiber)]
    for fiber in fibers:
        split_fiber(network, fiber, bounds, target, equipment)

    roadms = [r for r in network.nodes() if isinstance(r, Roadm)]
    for roadm in roadms:
        add_egress_amplifier(network, roadm, equipment)