def calculate_adjacent_jitter(graph, u):
"""计算一个节点的jitter"""
jitter_sum = 0
for v in range(graph.number_of_nodes()):
if u == v:
pass
else:
path = Network.k_shortest_path(graph, u, v, 1)[0]
jitter_sum += Evaluation.calculate_jitter(graph, path)
return jitter_sum / (graph.number_of_nodes() - 1)
def cut_then_map(sub, req, node_map, algorithm_name):
"""求解链路映射问题"""
link_map = {}
sub_copy = copy.deepcopy(sub)
for vLink in req.edges:
vn_from, vn_to = vLink[0], vLink[1]
resource = req[vn_from][vn_to]['bw']
# 剪枝操作，先暂时将那些不满足当前待映射虚拟链路资源需求的底层链路删除
sub_tmp = copy.deepcopy(sub_copy)
sub_edges = []
for sLink in sub_tmp.edges:
sub_edges.append(sLink)
for edge in sub_edges:
sn_from, sn_to = edge[0], edge[1]
if sub_tmp[sn_from][sn_to]['bw_remain'] <= resource:
sub_tmp.remove_edge(sn_from, sn_to)
vdl = req.graph['delay']
vjt = req.graph['jitter']
vpl = req.graph['packetloss']
k = Network.get_qos_class(req)
# 在剪枝后的底层网络上寻找一条可映射的最短路径
sn_from, sn_to = node_map[vn_from], node_map[vn_to]
if nx.has_path(sub_tmp, source=sn_from, target=sn_to):
for path in Network.k_shortest_path(sub_tmp, sn_from, sn_to,
1):
if algorithm_name == "MC":
sdl = Evaluation.calculate_delay(sub, path)
if sdl <= req.graph['delay']:
link_map.update({vLink: path})
# 这里的资源分配是暂时的
start = path[0]
for end in path[1:]:
bw_tmp = sub_copy[start][end][
'bw_remain'] - resource
sub_copy[start][end]['bw_remain'] = round(
bw_tmp, 6)
start = end
break
else:
continue
elif algorithm_name == "RLD":
sdl = Evaluation.calculate_delay(sub, path)
if sdl <= k * vdl:
link_map.update({vLink: path})
# 这里的资源分配是暂时的
start = path[0]
for end in path[1:]:
bw_tmp = sub_copy[start][end][
'bw_remain'] - resource
sub_copy[start][end]['bw_remain'] = round(
bw_tmp, 6)
start = end
break
else:
continue
elif algorithm_name == "RLJ":
sdl = Evaluation.calculate_delay(sub, path)
sjt = Evaluation.calculate_jitter(sub, path)
if sdl <= k * vdl and sjt <= k * vjt:
link_map.update({vLink: path})
# 这里的资源分配是暂时的
start = path[0]
for end in path[1:]:
bw_tmp = sub_copy[start][end][
'bw_remain'] - resource
sub_copy[start][end]['bw_remain'] = round(
bw_tmp, 6)
start = end
break
else:
continue
elif algorithm_name == "RLQ":
sdl = Evaluation.calculate_delay(sub, path)
sjt = Evaluation.calculate_jitter(sub, path)
spl = Evaluation.calculate_packet_loss(sub, path)
if sdl <= k * vdl and sjt <= k * vjt and spl <= k * vpl:
link_map.update({vLink: path})
# 这里的资源分配是暂时的
start = path[0]
for end in path[1:]:
bw_tmp = sub_copy[start][end][
'bw_remain'] - resource
sub_copy[start][end]['bw_remain'] = round(
bw_tmp, 6)
start = end
break
else:
continue
else:
break
# 返回链路映射集合
return link_map
