出现此错误的任何原因？在查看 ryu 拓扑查看器时遇到问题

如何解决出现此错误的任何原因？在查看 ryu 拓扑查看器时遇到问题

集线器：未捕获的异常：

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/ryu/lib/hub.py",line 60,in _launch
    return func(*args,**kwargs)
  File "/usr/local/lib/python3.8/dist-packages/ryu/controller/controller.py",line 211,in server_loop
    server = StreamServer((CONF.ofp_listen_host,File "/usr/local/lib/python3.8/dist-packages/ryu/lib/hub.py",line 127,in __init__
    self.server = eventlet.listen(listen_info)
  File "/usr/local/lib/python3.8/dist-packages/eventlet/convenience.py",line 78,in listen
    sock.bind(addr)
OSError: [Errno 98] Address already in use