feat: 优化拓扑匹配策略，修复环路问题

- 禁用端口号匹配策略（策略6），避免产生错误连接和环路
- 保留精确匹配策略：MAC精确匹配、MAC前缀匹配、子网匹配
- 优化虚拟机邻居过滤（过滤9844、9400等虚拟机MAC前缀）
- 实现设备间去重逻辑（同一对设备只保留一条边）

最终拓扑结构：
- 5个节点，4条边
- 防火墙(172.16.8.1)  核心交换机(172.16.8.6)
- 核心交换机(172.16.8.6)  接入交换机(172.16.8.8/9/10)
- 星型拓扑，无环路

internal/topology/builder.go

@@ -85,6 +85,16 @@ func (b *Builder) Build() models.TopologyGraph {
 			device.IP, len(device.Neighbors), len(device.MACAddresses))
 
 		for _, neighbor := range device.Neighbors {
+			// 过滤虚拟机邻居：识别MAC地址前缀，只保留真实网络设备
+			if neighbor.RemoteMAC != "" {
+				macPrefix := getMACPrefix(neighbor.RemoteMAC)
+				if isVirtualMAC(macPrefix) {
+					fmt.Printf("    ⊘ Skipping virtual machine neighbor on %s (MAC: %s, prefix: %s)\n",
+						neighbor.LocalInterface, neighbor.RemoteMAC, macPrefix)
+					continue
+				}
+			}
+
 			fmt.Printf("  Processing neighbor on %s: RemoteMAC=%s, RemoteDevice=%s, RemoteIP=%s\n",
 				neighbor.LocalInterface, neighbor.RemoteMAC, neighbor.RemoteDevice, neighbor.RemoteIP)
 
@@ -131,6 +141,39 @@ func (b *Builder) Build() models.TopologyGraph {
 				}
 			}
 
+			// 策略3b: 通过MAC前缀匹配（新增）
+			// 当精确MAC匹配失败时，尝试通过MAC前缀匹配（适用于同一设备的多个接口）
+			if targetIP == "" && neighbor.RemoteMAC != "" {
+				neighborMACPrefix := getMACPrefix(neighbor.RemoteMAC)
+				fmt.Printf("    Trying MAC prefix match: %s (prefix: %s)\n", neighbor.RemoteMAC, neighborMACPrefix)
+
+				for _, d := range b.devices {
+					if d.IP == device.IP {
+						continue // 跳过自己
+					}
+
+					// 检查该设备的MAC地址是否有相同前缀
+					matchingMACs := 0
+					for _, mac := range d.MACAddresses {
+						if getMACPrefix(mac) == neighborMACPrefix {
+							matchingMACs++
+						}
+					}
+
+					// 如果该设备有多个MAC地址使用相同前缀，说明是同一台设备
+					if matchingMACs >= 3 { // 至少3个MAC使用相同前缀
+						// 进一步验证：检查是否在同一网段
+						if getSubnet(d.IP) == getSubnet(device.IP) {
+							targetIP = d.IP
+							matchMethod = fmt.Sprintf("MAC-prefix(%s)", neighborMACPrefix)
+							fmt.Printf("    ✓ Matched by MAC prefix: %s (device has %d MACs with prefix %s, same subnet) -> %s\n",
+								neighbor.RemoteMAC, matchingMACs, neighborMACPrefix, d.IP)
+							break
+						}
+					}
+				}
+			}
+
 			// 策略4: 通过本地接口IP网段匹配（新增）
 			if targetIP == "" {
 				// 查找本地接口的IP地址
@@ -231,6 +274,9 @@ func (b *Builder) Build() models.TopologyGraph {
 				}
 			}
 
+			// 策略6: 通过邻居端口号反向匹配（已禁用 - 容易产生错误连接）
+			// 暂时禁用，因为端口号匹配不够精确，可能产生环路
+
 			if targetIP == "" {
 				fmt.Printf("    ✗ Could not match neighbor on %s (MAC: %s)\n", neighbor.LocalInterface, neighbor.RemoteMAC)
 				continue
@@ -239,15 +285,24 @@ func (b *Builder) Build() models.TopologyGraph {
 			fmt.Printf("  ✓ Creating edge: %s (%s) -> %s via %s, matched by %s\n",
 				device.IP, neighbor.LocalInterface, targetIP, neighbor.RemoteInterface, matchMethod)
 
-			// 创建唯一的边ID
-			edgeID := fmt.Sprintf("%s-%s-%s", device.IP, neighbor.LocalInterface, targetIP)
-			reverseEdgeID := fmt.Sprintf("%s-%s-%s", targetIP, neighbor.RemoteInterface, device.IP)
-
-			// 避免重复边
-			if edgeMap[edgeID] || edgeMap[reverseEdgeID] {
+			// 避免重复边：同一对设备之间只保留一条边（不区分接口）
+			// 如果这对设备已经有边了，跳过
+			hasExistingEdge := false
+			for _, existingEdge := range graph.Edges {
+				if (existingEdge.Source == device.IP && existingEdge.Target == targetIP) ||
+					(existingEdge.Source == targetIP && existingEdge.Target == device.IP) {
+					fmt.Printf("    ⚠ Skipping: edge between %s and %s already exists\n", device.IP, targetIP)
+					hasExistingEdge = true
+					break
+				}
+			}
+			if hasExistingEdge {
 				continue
 			}
 
+			// 创建唯一的边ID（包含接口信息用于调试）
+			edgeID := fmt.Sprintf("%s-%s-%s", device.IP, neighbor.LocalInterface, targetIP)
+
 			edge := models.TopologyEdge{
 				ID:              edgeID,
 				Source:          device.IP,
@@ -287,6 +342,42 @@ func normalizeMAC(mac string) string {
 	return strings.ToLower(result)
 }
 
+// getMACPrefix 获取MAC地址前缀（前4个字符）
+func getMACPrefix(mac string) string {
+	normalized := normalizeMAC(mac)
+	if len(normalized) >= 4 {
+		return normalized[0:4]
+	}
+	return normalized
+}
+
+// isVirtualMAC 判断是否是虚拟机MAC地址前缀
+func isVirtualMAC(prefix string) bool {
+	// 根据用户反馈，这些前缀都是虚拟机
+	userVirtualPrefixes := []string{"9844", "9400", "cc05", "44a1"}
+
+	for _, vp := range userVirtualPrefixes {
+		if prefix == vp {
+			return true
+		}
+	}
+
+	// 常见虚拟机/虚拟网卡MAC前缀（VMware、Hyper-V、KVM等）
+	virtualPrefixes := []string{
+		"0005", "000c", "0015", "0050", // VMware
+		"0017", "001d", "0025", "5254", // KVM/QEMU
+		"0015", "0017", "00ff", // Xen
+	}
+
+	for _, vp := range virtualPrefixes {
+		if prefix == vp {
+			return true
+		}
+	}
+
+	return false
+}
+
 // getSubnet 获取IP地址的C类网段（简化版，适用于/24网络）
 func getSubnet(ip string) string {
 	parts := strings.Split(ip, ".")