动态源路由自组网实现全解析

实现 Ad hoc DSR（动态源路由）自组网需要处理路由发现、路由维护、数据包转发等核心功能。以下是一个详细实现示例，包含关键函数和逻辑：

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网络节点类

定义一个节点类，包含地址、邻居、路由表等属性：

class Node:
    def __init__(self, address):
        self.address = address
        self.neighbors = set()  # 存储邻居节点地址
        self.routing_table = {}  # 格式: {dest: [path], ...}
        self.route_cache = {}    # 缓存路由请求
        self.seq_num = 0         # 序列号用于路由请求

邻居发现

定期广播心跳消息以维护邻居列表：

def discover_neighbors(self, network):
    for node in network.nodes:
        if node.address != self.address and self._is_in_range(node):
            self.neighbors.add(node.address)
    # 超时处理（需另实现）

路由请求（RREQ）

发起路由发现过程：

def send_route_request(self, dest, network):
    self.seq_num += 1
    rreq = {
        'src': self.address,
        'dest': dest,
        'seq_num': self.seq_num,
        'path': [self.address]
    }
    self.route_cache[(self.address, dest, self.seq_num)] = rreq
    self._broadcast(rreq, network)

广播路由请求

def _broadcast(self, packet, network):
    for neighbor_addr in self.neighbors:
        neighbor = network.get_node(neighbor_addr)
        if neighbor:
            neighbor.process_packet(packet.copy())

处理路由请求

中间节点处理RREQ：

def process_route_request(self, rreq):
    # 检查是否已处理过该请求
    key = (rreq['src'], rreq['dest'], rreq['seq_num'])
    if key in self.route_cache:
        return
    
    self.route_cache[key] = rreq
    rreq['path'].append(self.address)
    
    # 如果是目标节点则回复，否则继续广播
    if rreq['dest'] == self.address:
        self._send_route_reply(rreq)
    else:
        self._broadcast(rreq)

路由回复（RREP）

目标节点生成回复：

def _send_route_reply(self, rreq):
    rrep = {
        'src': rreq['dest'],
        'dest': rreq['src'],
        'path': list(reversed(rreq['path']))
    }
    next_hop = rrep['path'][1]  # 路径的下一跳
    self._unicast(rrep, next_hop)

单播转发

def _unicast(self, packet, next_hop):
    neighbor = network.get_node(next_hop)
    if neighbor:
        neighbor.process_packet(packet)

路由维护

检测链路断裂并触发错误处理：

def check_link_status(self):
    for neighbor in list(self.neighbors):
        if not self._is_link_active(neighbor):
            self._handle_link_break(neighbor)

def _handle_link_break(self, neighbor):
    # 查找使用该邻居的路由并触发RERR
    for dest, path in self.routing_table.items():
        if neighbor in path:
            self._send_route_error(dest)
            del self.routing_table[dest]

数据包转发

def forward_data(self, packet):
    if packet['dest'] in self.routing_table:
        path = self.routing_table[packet['dest']]
        next_hop = path[path.index(self.address) + 1]
        self._unicast(packet, next_hop)
    else:
        self.send_route_request(packet['dest'])

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关键点说明

1. 路由发现：通过RREQ洪泛和RREP反向路径建立路由
2. 路由缓存：节点缓存路由请求以避免重复处理
3. 序列号：防止路由请求循环
4. 链路维护：定期检测邻居存活状态

完整实现还需要添加网络模拟环境、计时器、日志记录等辅助功能。实际部署时需考虑无线信号衰减、移动性管理等现实问题。