Cisco 交换机利用CDP数据自动绘制网络拓扑图[drawio]-实践

来源：cnblogs　　作者：颜天高佑　　时间：2023/12/26 9:52:37　　对本文有异议

进行网络运维，必须对网络拓扑情况进行详细的掌握，但是网络改动后，更新网络拓扑比较繁琐，维护人员容易懈怠，久而久之，通过人工绘制的网络拓扑很容易与现有网络出现偏差。

现在，可以通过python 丰富的库，结合CDP邻居信息，自动绘制网络拓扑信息，以下是实现思路：

1、登录设备，获取邻居信息；

　　工具：python（telnetlib、paramiko、netmiko库）

2、筛选需要的信息，设备本地IP，本地名称，本地接口，对端设备名称，对端接口，对端IP

　　工具:python（textfsm、json库）

3、根据获取进行进行画图

　　工具：python（N2G库）

　　文档说明：https://n2g.readthedocs.io/en/latest/diagram_plugins/DrawIo%20Module.html

4、调整图形。

一、通过python登录交换机设备的案例很多，在此不再赘述，各位可以在网上找到通过telnet、ssh的方式登录交换机，根据实际情况进行调整；这里后续通过telnet方式登录设备，输入show cdp nei detali 获取信息。

二、邻居信息处理

　　2.1获取邻居信息

　　　　输入命令后，获取交换机邻居信息如下：

 1 QIA.JSJZX.JKS>show cdp nei
 2 -------------------------
 3 Device ID: qia.b3.net.test.sw01
 4 Entry address(es):
 5   IP address: 192.17.190.225
 6 Platform: cisco WS-C2960X-24TS-L,  Capabilities: Switch IGMP
 7 Interface: GigabitEthernet1/0/24,  Port ID (outgoing port): GigabitEthernet1/0/23
 8 Holdtime : 126 sec
 9 
10 Version :
11 Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.2(2)E6, RELEASE SOFTWARE (fc1)
12 Technical Support: http://www.cisco.com/techsupport
13 Copyright (c) 1986-2016 by Cisco Systems, Inc.
14 Compiled Fri 16-Dec-16 21:27 by prod_rel_team
15 
16 advertisement version: 2
17 Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF000000000000F87B20311580FF0000
18 VTP Management Domain: ''
19 Native VLAN: 1
20 Duplex: full
21 Power Available TLV:
22 
23     Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
24 Management address(es):
25   IP address: 192.17.190.225
26 
27 -------------------------
28 Device ID: qia.b3.net.test.sw03
29 Entry address(es):
30   IP address: 192.17.191.132
31 Platform: cisco WS-C2960S-48TD-L,  Capabilities: Switch IGMP
32 Interface: GigabitEthernet1/0/23,  Port ID (outgoing port): GigabitEthernet1/0/48
33 Holdtime : 134 sec
34 
35 Version :
36 Cisco IOS Software, C2960S Software (C2960S-UNIVERSALK9-M), Version 12.2(55)SE7, RELEASE SOFTWARE (fc1)
37 Technical Support: http://www.cisco.com/techsupport
38 Copyright (c) 1986-2013 by Cisco Systems, Inc.
39 Compiled Mon 28-Jan-13 10:28 by prod_rel_team
40 
41 advertisement version: 2
42 Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF000000000000B000B4865F80FF0000
43 VTP Management Domain: 'default'
44 Native VLAN: 1
45 Duplex: full
46 Power Available TLV:
47 
48     Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
49 Management address(es):
50   IP address: 192.19.191.132

上述为邻居信息字段，标红部分为需要提取的信息内容，下面通过textfsm工具进行提取，获取到信息内容分别为：本机名称，邻居主机名称、邻居主机IP、本机接口、邻居接口；以下是自定义的textfsm模板，文件保存为cisco_tfm.template。

 1 Value Local_hostname (\S+)
 2 Value Key Local_port (\S+)
 3 Value Device_name (\S+)
 4 Value Device_module (\S+)
 5 Value Device_IP (\S+)
 6 Value Required Device_port (\S+)
 7 
 8 
 9 Start
10  ^${Local_hostname}>
11  ^Device ID: ${Device_name}
12  ^\s+IP\saddress: ${Device_IP}
13  ^Platform: cisco ${Device_module},
14  ^Interface: ${Local_port},\s+Port\sID\s\(outgoing\sport\):\s${Device_port} -> Record

代码实现：

 1 import textfsm
 2 
 3 
 4 #cisco :show cdp nei detail
 5 data = """
 6 QIA.JSJZX.JKS>show cdp nei
 7 -------------------------
 8 Device ID: qia.b3.net.test.sw01
 9 Entry address(es):
10   IP address: 192.17.190.225
11 Platform: cisco WS-C2960X-24TS-L,  Capabilities: Switch IGMP
12 Interface: GigabitEthernet1/0/24,  Port ID (outgoing port): GigabitEthernet1/0/23
13 Holdtime : 126 sec
14 
15 Version :
16 Cisco IOS Software, C2960X Software (C2960X-UNIVERSALK9-M), Version 15.2(2)E6, RELEASE SOFTWARE (fc1)
17 Technical Support: http://www.cisco.com/techsupport
18 Copyright (c) 1986-2016 by Cisco Systems, Inc.
19 Compiled Fri 16-Dec-16 21:27 by prod_rel_team
20 
21 advertisement version: 2
22 Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF000000000000F87B20311580FF0000
23 VTP Management Domain: ''
24 Native VLAN: 1
25 Duplex: full
26 Power Available TLV:
27 
28     Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
29 Management address(es):
30   IP address: 192.17.190.225
31 
32 -------------------------
33 Device ID: qia.b3.net.test.sw03
34 Entry address(es):
35   IP address: 192.17.191.132
36 Platform: cisco WS-C2960S-48TD-L,  Capabilities: Switch IGMP
37 Interface: GigabitEthernet1/0/23,  Port ID (outgoing port): GigabitEthernet1/0/48
38 Holdtime : 134 sec
39 
40 Version :
41 Cisco IOS Software, C2960S Software (C2960S-UNIVERSALK9-M), Version 12.2(55)SE7, RELEASE SOFTWARE (fc1)
42 Technical Support: http://www.cisco.com/techsupport
43 Copyright (c) 1986-2013 by Cisco Systems, Inc.
44 Compiled Mon 28-Jan-13 10:28 by prod_rel_team
45 
46 advertisement version: 2
47 Protocol Hello:  OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF000000000000B000B4865F80FF0000
48 VTP Management Domain: 'default'
49 Native VLAN: 1
50 Duplex: full
51 Power Available TLV:
52 
53     Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
54 Management address(es):
55   IP address: 192.17.191.132
56 """
57 
58 template_file = ".\cisco_tfm.template"
59 
60 with open(template_file) as template:
61     fsm = textfsm.TextFSM(template)
62     result = fsm.ParseText(data)
63     # print(fsm.header)
64     print(result)
65     # print(len(result))

输出内容：

['Local_hostname', 'Local_port', 'Device_name', 'Device_module', 'Device_IP', 'Device_port']
[['QIA.JSJZX.JKS', 'GigabitEthernet1/0/24', 'qia.b3.net.test.sw01', 'WS-C2960X-24TS-L', '192.17.190.225', 'GigabitEthernet1/0/23'], 
 ['', 'GigabitEthernet1/0/23', 'qia.b3.net.test.sw03', 'WS-C2960S-48TD-L', '192.17.191.132', 'GigabitEthernet1/0/48']]

注意：以上内容中，本地主机名仅在第一个邻居信息表中显示，所以需要当前设备邻居进行数据进行格式化，因此就需要用到json库。
2.2 邻居信息数据格式化
通过数据格式转换，可以得到当前主机IP、主机名称、主机接口；邻居IP、邻居名称、邻居接口信息；
代码实现：

 1 import json
 2 
 3 ip_address = '192.168.1.1'
 4 # hostname = 'zh_cisco_2960'
 5 
 6 cdp_data = [
 7     ['9QI.JSJZX.JKS', 'GigabitEthernet1/0/24', '9qi.b3.net.test.sw01', 'WS-C2960X-24TS-L', '172.17.190.225', 'GigabitEthernet1/0/23'],
 8     ['', 'GigabitEthernet1/0/23', '9qi.b3.net.test.sw03', 'WS-C2960S-48TD-L', '172.17.191.132', 'GigabitEthernet1/0/48']
 9 ]
10 
11 def data_format(ip_address,cdp_data):
12     
13     hostname = cdp_data[0][0]#二层列表格式，获取主机名
14     result_data = {
15         ip_address: {
16             hostname: {item[1]: item[2:] for item in cdp_data}
17         }
18     }
19     json_data = json.dumps(result_data, indent=2)
20 
21     return json_data
22 # return the JSON formatted string
23 
24 if __name__ == "__main__":
25     json_data1 = data_format(ip_address,cdp_data)
26     print(json_data1)

Json_CDPInfo

输出信息：

 1 {
 2   "192.168.1.1": {#当前设备IP
 3     "QI.JSJZX.JKS": {#当前设备名称
 4       "GigabitEthernet1/0/24": [#本地接口，
 5         "qia.b3.net.test.sw01",#邻居信息
 6         "WS-C2960X-24TS-L",
 7         "192.17.190.225",
 8         "GigabitEthernet1/0/23"
 9       ],
10       "GigabitEthernet1/0/23": [
11         "qia.b3.net.test.sw03",
12         "WS-C2960S-48TD-L",
13         "192.17.191.132",
14         "GigabitEthernet1/0/48"
15       ]
16     }
17   }
18 }

View Code

格式化以上邻居数据后，便于后续对数据进行遍历，在第三步进行读取数据进行增加节点。

遍历数据：

 1 import json
 2 
 3 # 读取 JSON 数据
 4 json_data = '''
 5 {
 6   "192.168.1.1": {
 7     "QIA.JSJZX.JKS": {
 8       "GigabitEthernet1/0/24": [
 9         "qia.b3.net.test.sw01",
10         "WS-C2960X-24TS-L",
11         "192.17.190.225",
12         "GigabitEthernet1/0/23"
13       ],
14       "GigabitEthernet1/0/23": [
15         "qia.b3.net.test.sw03",
16         "WS-C2960S-48TD-L",
17         "192.17.191.132",
18         "GigabitEthernet1/0/48"
19       ]
20     }
21   }
22 }
23 
24 '''
25 
26 # 解析 JSON 数据
27 parsed_data = json.loads(json_data)
28 
29 # 遍历数据
30 for ip_address, inner_data in parsed_data.items():
31     print(f"IP Address: {ip_address}")# 获取主机IP地址
32     # print(f"host: {inner_data}")
33 
34     for hostname, cdp_data in inner_data.items():
35       print(f"Hostname: {hostname}") #获取主机名称
36       # print(type(cdp_data))
37 
38       for key, values in cdp_data.items():
39         print(values)

View Code

这里在每个节点获取到邻居信息，就可以根据信息，在拓扑图中增加节点信息了。

三、进行画图、

3.1 小试牛刀

网络拓扑图中，最重要的信息就是节点和互联线路，其他都为辅助信息

在官方文档中，已经有详细的说明可以增加节点（addnode）、增加连线（addlink）；在这个两个功能中，还有其他的选项，可以补充增加，官方提供的方法，可以通过help 查看文档说明help（N2G.plugins.diagrams.N2G_DrawIO.drawio_diagram）

这里只需要重点查看Quick start部分增加节点和连接就可以了。

1 from N2G import drawio_diagram
2 
3 diagram = drawio_diagram()#
4 diagram.add_diagram("Page-1")
5 diagram.add_node(id="R1")#增加节点
6 diagram.add_node(id="R2")#增加节点
7 diagram.add_link("R1", "R2", label="DF", src_label="Gi1/1", trgt_label="GE23")#增加节点之间的连线，标签名称，src_lable和trgt_lable 可以用来标注端口
8 diagram.layout(algo="kk")#图层，不重要
9 diagram.dump_file(filename="Sample_graph.drawio", folder="./Output/")#保存拓扑图

以上示例是官方最简单的画图程序，自己可以多增加几个节点进行练习。

但是在网络情况里，对每个邻居节点都登录检测检查邻居信息时，会遇到同一个连接，在两台设备上都能发现，那么创建节点和连接时会出现什么情况呢？

这里官方有说明，如果发现节点已经存在就直接跳过（也可以自定义），这样我们再写程序上就简单很多，链接里有说明。

3.2 完成程序输出

  1 from N2G import drawio_diagram
  2 import textfsm
  3 import json
  4 import telnetlib
  5 import time
  6 
  7 
  8 file_path = './host_1218.txt'
  9 #主机IP清单，格式如下：
 10 #cisco 192.168.1.1 cisco cisco
 11 
 12 
 13 template_file = "./cisco_tfm.template"
 14 style_cisco = "verticalLabelPosition=bottom;html=1;verticalAlign=top;aspect=fixed;align=center;pointerEvents=1;shape=mxgraph.cisco19.rect;prIcon=l2_switch;fillColor=#FAFAFA;strokeColor=#005073;"
 15 # 图标格式
 16 
 17 def data_format(ip_address,cdp_data):
 18     
 19     hostname = cdp_data[0][0]#二层列表格式，获取主机名
 20     result_data = {
 21         ip_address: {
 22             hostname: {item[1]: item[2:] for item in cdp_data}
 23         }
 24     }
 25     json_data = json.dumps(result_data, indent=2)
 26 
 27     return json_data
 28 # return the JSON formatted string
 29 
 30 
 31 def cisco_telent(ip, username, password, cmd):
 32     # 创建Telnet连接
 33     tn = telnetlib.Telnet(ip)
 34     time.sleep(0.1)
 35 
 36     tn.read_until(b"Username:")
 37     tn.write(username.encode('ascii') + b"\n")
 38 
 39     tn.read_until(b"Password: ")
 40     tn.write(password.encode('ascii') + b"\n")
 41     tn.write(b"terminal length 0\n")
 42 
 43     tn.write(cmd.encode('ascii') + b"\n")
 44 
 45     time.sleep(0.5)
 46     tn.write(b"exit\n")
 47     # # 读取输出并打印
 48     output = tn.read_very_eager().decode('ascii')
 49 
 50     tn.close() # 关闭连接
 51     return output
 52 
 53 
 54 diagram = drawio_diagram()
 55 diagram.add_diagram("Page-1")
 56 
 57 host_info_dict = {}
 58 
 59 node_num = 0
 60 #节点计数
 61 # 打开文件进行读取
 62 with open(file_path, 'r') as file:
 63     for line in file:
 64         # 分割每一行以获取主机信息
 65         host_info = line.strip().split()
 66 
 67         # 检查是否有足够的信息
 68         if len(host_info) == 4:
 69             device_type, ip, username, password = host_info
 70 
 71             # 构建设备字典
 72             device = {
 73                 'device_type': device_type,
 74                 'ip': ip,
 75                 'username': username,
 76                 'password': password,
 77             }
 78 
 79             try:
 80                 # 执行telnet
 81 
 82                 cmd = 'show cdp neighbors detail'
 83 
 84                 command_output = cisco_telent(ip, username, password, cmd)
 85                 with open(template_file) as template:
 86                     #打开模板，进行数据提取
 87                     fsm = textfsm.TextFSM(template)
 88                     result = fsm.ParseText(command_output)
 89                     #列表格式数据，需要进行转换
 90 
 91                     nei_info_format = data_format(ip,result)
 92                     # print(nei_info_format)
 93                     parsed_data = json.loads(nei_info_format)
 94 
 95                     for ip_address, inner_data in parsed_data.items():
 96                         for local_hostname, cdp_data in inner_data.items():
 97                             if local_hostname not in host_info_dict:
 98                                 #节点不存在，进行创建节点并保存节点信息
 99                                 diagram.add_node(id=ip_address,name= local_hostname, style =style_cisco, width=60, height=60)
100                                 #增加本机节点
101                                 node_num += 1
102                                 # print(ip_address, local_hostname)
103                                 host_info_dict[local_hostname] = ip_address
104                                 # print(host_info_dict) 节点主机名和IP信息保存，后续进行校验节点是否已经存在
105 
106                                 for src_label, values in cdp_data.items():
107                                     nei_host_name, nei_host_module, nei_host_id, trgt_label = values
108                                     #如果邻居节点不存在，直接创建；如果节点已经存在，则邻居ID信息要更新，更换成已经存在节点的IP地址（）
109                                     if nei_host_name not in host_info_dict:
110                                         diagram.add_node(id=nei_host_id,name=nei_host_name,style=style_cisco, width=60, height=60)
111                                         #根据邻居信息，增加邻居节点
112                                         host_info_dict[nei_host_name] = nei_host_id
113                                         print("Add node " + nei_host_id + "secuessed.")
114                                         node_num += 1
115                                         diagram.add_link(ip_address, nei_host_id, src_label=src_label, trgt_label=trgt_label)
116                                     else:
117                                         nei_host_id = host_info_dict[nei_host_name]
118                                         diagram.add_link(ip_address, nei_host_id, src_label=src_label, trgt_label=trgt_label)
119                             else:
120                                 print('节点已存在：' + local_hostname + ip_address)
121                                 #节点存在，检查邻居信息，根据邻居信息进行判断，是否添加邻居节点
122                                 for src_label, values in cdp_data.items():
123                                     nei_host_name, nei_host_module, nei_host_id, trgt_label = values
124                                     if nei_host_name not in host_info_dict:
125                                         diagram.add_node(id=nei_host_id, name=nei_host_name, style=style_cisco, width=60, height=60)
126                                         #根据邻居信息，增加邻居节点
127                                         host_info_dict[nei_host_name] = nei_host_id
128                                         print("Add node " + nei_host_id + "secuessed.")
129                                         node_num += 1
130                                         diagram.add_link(ip_address, nei_host_id, src_label=src_label, trgt_label=trgt_label)
131                                     else:
132                                         nei_host_id = host_info_dict[nei_host_name]
133                                         diagram.add_link(ip_address, nei_host_id, src_label=src_label, trgt_label=trgt_label)
134 
135                             # print("Add node " + ip_address + " sucessed.")        
136 
137             except Exception as e:
138                 print(f"Failed to connect to {ip}: {e}")
139 
140         else:
141             print(f"Invalid line in the file: {line.strip()}")
142 print(node_num)
143 print(host_info_dict,len(host_info_dict))
144 diagram.dump_file(filename="Sample_campus_00.drawio", folder="./Output/")