写一个程序来模拟网桥功能

好的，我可以给你提供一个简单的 Python 程序来模拟网桥的基本功能：

class Bridge:
    def __init__(self, bridge_id):
        self.bridge_id = bridge_id
        self.port_states = {}
        self.mac_table = {}

    def receive_frame(self, port, frame):
        src_mac = frame['src_mac']
        dst_mac = frame['dst_mac']

        # Learn source MAC address
        self.mac_table[src_mac] = port

        # Check destination MAC address
        if dst_mac in self.mac_table:
            dst_port = self.mac_table[dst_mac]
            if dst_port != port:
                # Forward frame to destination port
                self.forward_frame(dst_port, frame)
        else:
            # Flood frame to all ports except source port
            for p in self.port_states:
                if p != port:
                    self.forward_frame(p, frame)

    def forward_frame(self, port, frame):
        print(f'Bridge {self.bridge_id} forwarding frame to port {port}: {frame}')
        self.port_states[port]['state'] = 'forwarding'

    def add_port(self, port_id, state):
        self.port_states[port_id] = {'state': state}

    def remove_port(self, port_id):
        del self.port_states[port_id]


# Example usage:
bridge1 = Bridge(1)
bridge1.add_port(1, 'forwarding')
bridge1.add_port(2, 'forwarding')

frame1 = {'src_mac': '00:11:22:33:44:55', 'dst_mac': 'aa:bb:cc:dd:ee:ff', 'data': 'Hello world!'}
bridge1.receive_frame(1, frame1)

frame2 = {'src_mac': 'aa:bb:cc:dd:ee:ff', 'dst_mac': '00:11:22:33:44:55', 'data': 'Goodbye!'}
bridge1.receive_frame(2, frame2)

这个程序定义了一个 `Bridge` 类来表示一个网桥，它可以添加/移除端口并接收/转发帧。网桥维护一个 MAC 地址表来学习每个源 MAC 地址对应的端口，并根据目的 MAC 地址将帧转发到正确的端口。如果目的 MAC 地址没有在表中找到，则将帧泛洪到所有端口（除源端口外）。