在我们的主楼和街对面一座建筑物中的这个交换机之间设置了一个无线 Ubiquity 网桥。Ubiquity 连接似乎从来没有任何问题，只是 cisco。每隔几天，Cisco 就会离线（因此整个建筑物都会离线），恢复它的唯一方法是拔下/重新插入中继端口。我们更换了所有电缆并尝试了不同的交换机端口。我们每隔几分钟就会在 cisco 日志中输出一个重复出现的问题，如下所示：
Feb 19 14:12:31.200 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 2
Feb 19 14:12:32.191 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to up
Feb 19 14:14:55.700 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to down
Feb 19 14:14:56.644 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/48, changed state to down
Feb 19 14:14:57.666 Pacific: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/48, changed state to down
Feb 19 14:15:00.162 Pacific: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/48, changed state to up
Feb 19 14:15:01.164 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/48, changed state to up
Feb 19 14:15:16.217 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 19 14:15:16.223 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 10
Feb 19 14:15:17.250 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 2: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 19 14:15:17.256 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 2
Feb 19 14:15:17.303 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to up
Feb 19 14:26:48.075 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 20: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 19 14:26:53.569 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 20: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 19 14:36:43.014 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to down
Feb 19 14:36:43.958 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/48, changed state to down
Feb 19 14:36:44.980 Pacific: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/48, changed state to down
Feb 19 14:36:47.476 Pacific: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/48, changed state to up
Feb 19 14:36:48.477 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/48, changed state to up
Feb 19 14:37:15.505 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 2
Feb 19 14:37:15.532 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to up
Feb 19 14:37:18.122 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 10
Feb 19 14:37:18.122 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 19 14:37:19.165 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 7
Feb 19 14:37:19.165 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 7: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
端口配置如下：
interface GigabitEthernet1/0/48
switchport trunk native vlan 10
switchport trunk allowed vlan 2-1088
switchport mode trunk
switchport nonegotiate
mls qos trust dscp
更新
图：
生成树对我来说仍然是一个新概念，所以我希望有人能够提供帮助。如果您需要更多信息，请告诉我。
更新： 我今天刚刚在我们主楼 (Cisco 3750) 交换机的日志中发现了这些消息，当时街对面的交换机已关闭：
Feb 20 02:29:42.386 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:30:42.420 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:31:42.412 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:32:42.421 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:33:42.430 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:34:42.431 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
Feb 20 02:35:42.440 Pacific: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/45 (not half duplex), with 222-core-2960 GigabitEthernet1/0/48 (half duplex).
更新 2/24 我们对配置进行了一些更改并测试/更换了所有物理硬件和电缆（无线网桥上的端口除外......），但仍然存在问题。似乎 LOOPGUARD_BLOCK 经常发生在我们遇到的短暂中断之前。这是日志中的另一个示例
Feb 24 10:13:22.819 Pacific: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/48 on VLAN0002.
Feb 24 10:13:22.867 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to down
Feb 24 10:13:23.852 Pacific: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/48 on VLAN0010.
Feb 24 10:13:37.291 Pacific: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet1/0/48 on VLAN0002.
Feb 24 10:13:37.291 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 2: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 24 10:13:37.296 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 2
Feb 24 10:13:37.348 Pacific: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1088, changed state to up
Feb 24 10:13:38.334 Pacific: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet1/0/48 on VLAN0010.
Feb 24 10:13:38.339 Pacific: %SPANTREE-5-ROOTCHANGE: Root Changed for vlan 10: New Root Port is GigabitEthernet1/0/48. New Root Mac Address is 442b.0387.5180
Feb 24 10:13:38.339 Pacific: %SPANTREE-5-TOPOTRAP: Topology Change Trap for vlan 10