公司负责某城市轨道交通设备维护，其中某车站网络架构为若干个二层交换机连接终端设备，二层交换机分主备路与车站三层交换机（主备机）进行连接，车站三层交换机主备机（各一路）分别与中心网络设备连接（通过专业通信传输设备，可以理解成透明的网线），最近发现当三层交换机主机、备机与中心因sla协议切换主备路时，三层交换机与二层交换机之间发生usld和loop guard报警，三层交换机不切换主备路时无此告警。请教如何解决，硬件链路（网线、尾纤、水晶头已更换个变，无效果）。
三层交换机主要配置：
interface GigabitEthernet1/0/21
description to-'L3SWB-G1/0/21'
switchport trunk allowed vlan 1,118
switchport mode trunk
storm-control broadcast level 40.00
spanning-tree guard root
!
interface GigabitEthernet1/0/23
description to-'L2SW2-G0/23'
switchport trunk allowed vlan 1,118
switchport mode trunk
udld port aggressive
spanning-tree guard root
!
interface GigabitEthernet1/0/24
description to-'ChuanShu1'
no switchport
ip address 10.1.98.118 255.255.255.0
!
interface Vlan1
no ip address
shutdown
!
interface Vlan118
ip address 10.1.118.252 255.255.255.0
standby 118 ip 10.1.118.254
standby 118 priority 150
standby 118 preempt
standby 118 track 1 decrement 100
!
router eigrp 1
network 10.1.98.0 0.0.0.255
network 10.1.118.0 0.0.0.255
eigrp stub connected summary
!
ip sla 10
icmp-echo 10.1.98.1 source-interface GigabitEthernet1/0/24
threshold 3
timeout 1000
frequency 5
二层交换机主要配置：
interface GigabitEthernet0/23
description to-'L3SWM-G1/0/23'
switchport mode trunk
udld port aggressive
storm-control broadcast level 40.00
storm-control action shutdown
spanning-tree guard loop
spanning-tree vlan 118 cost 11
!
interface GigabitEthernet0/24
description to-'L3SWB-G1/0/23'
switchport mode trunk
udld port aggressive
storm-control broadcast level 40.00
spanning-tree guard loop
!
interface Vlan1
no ip address
shutdown
!
interface Vlan118
ip address 10.1.118.2 255.255.255.0
no ip route-cache
三层交换机日志：
Nov 8 18:20:21: %TRACK-6-STATE: 1 ip sla 10 reachability Up -> Down
Nov 8 18:20:23: %HSRP-5-STATECHANGE: Vlan118 Grp 118 state Active -> Speak
Nov 8 18:20:26: %TRACK-6-STATE: 1 ip sla 10 reachability Down -> Up
Nov 8 18:20:26: %HSRP-5-STATECHANGE: Vlan118 Grp 118 state Speak -> Active
Nov 8 18:21:35: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/0/23, aggressive mode failure detected
Nov 8 18:21:35: %PM-4-ERR_DISABLE: udld error detected on Gi1/0/23, putting Gi1/0/23 in err-disable state
Nov 8 18:21:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/23, changed state to down
Nov 8 18:21:37: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/23, changed state to down
Nov 8 21:21:35: %PM-4-ERR_RECOVER: Attempting to recover from udld err-disable state on Gi1/0/23
Nov 8 21:21:40: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/23, changed state to up
Nov 8 21:21:42: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/23, changed state to up
Nov 8 21:23:10: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/1/4, aggressive mode failure detected
Nov 8 21:23:10: %PM-4-ERR_DISABLE: udld error detected on Gi1/1/4, putting Gi1/1/4 in err-disable state
Nov 8 21:23:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/1/4, changed state to down
Nov 8 21:23:12: %UDLD-4-UDLD_PORT_DISABLED: UDLD disabled interface Gi1/0/22, aggressive mode failure detected
Nov 8 21:23:12: %PM-4-ERR_DISABLE: udld error detected on Gi1/0/22, putting Gi1/0/22 in err-disable state
Nov 8 21:23:12: %LINK-3-UPDOWN: Interface GigabitEthernet1/1/4, changed state to down
Nov 8 21:23:13: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/22, changed state to down
Nov 8 21:23:14: %LINK-3-UPDOWN: Interface GigabitEthernet1/0/22, changed state to down
二层交换机日志：
Nov 8 18:20:28: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/23 on VLAN0118.
Nov 8 18:20:28: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/23 on VLAN0118.
Nov 8 18:20:29: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/23 on VLAN0001.
Nov 8 18:20:29: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:20:34: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/23 on VLAN0118.
Nov 8 18:20:36: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/23 on VLAN0118.
Nov 8 18:20:37: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:20:40: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:20:46: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:20:47: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:20:49: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:20:55: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:20:57: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:20:57: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:20:59: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:21:01: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/23 on VLAN0001.
Nov 8 18:21:05: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/23 on VLAN0001.
Nov 8 18:21:07: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:09: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:21:13: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:18: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/23 on VLAN0118.
Nov 8 18:21:21: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:21: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:21:23: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:29: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:31: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/23 on VLAN0001.
Nov 8 18:21:31: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/23 on VLAN0001.
Nov 8 18:21:35: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:21:35: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:21:36: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:21:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/23, changed state to down
Nov 8 18:21:37: %LINK-3-UPDOWN: Interface GigabitEthernet0/23, changed state to down
Nov 8 18:22:25: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:22:27: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:22:34: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:22:35: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0118.
Nov 8 18:22:57: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet0/24 on VLAN0001.
Nov 8 18:22:57: %SPANTREE-2-LOOPGUARD_UNBLOCK: Loop guard unblocking port GigabitEthernet0/24 on VLAN0001.