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tech:network:cisco:stp:loopguard:loopguard

STP: Loop Guard

Topology

Log

  1. loopguard verification is difficult…
  2. loopguard, rootguard can configure exclusively. when loopguard enabled default, roop guard configuration works in Catalyst 2960 15.x.
SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#spa
SW1(config)#spann         
SW1(config)#spanning-tree loopgu
SW1(config)#spanning-tree loopguard defa
SW1(config)#spanning-tree loopguard default 
SW1(config)#^Z
SW1#
*Mar  1 09:01:55.258: %SYS-5-CONFIG_I: Configured from console by console
SW1#
*Mar  1 09:03:51.868: STP: VLAN0001 Topology Change rcvd on Fa1/0/1
*Mar  1 09:03:51.885: STP: VLAN0001 we are the spanning tree root
*Mar  1 09:03:51.885: STP[1]: Generating TC trap for port FastEthernet1/0/2
SW1#
*Mar  1 09:03:52.892: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/2, changed state to down
*Mar  1 09:03:53.898: %LINK-3-UPDOWN: Interface FastEthernet1/0/2, changed state to down
SW1#
*Mar  1 09:05:43.772: set portid: VLAN0001 Fa1/0/2: new port id 8004
*Mar  1 09:05:43.772: STP: VLAN0001 Fa1/0/2 -> listening
SW1#
*Mar  1 09:05:45.769: %LINK-3-UPDOWN: Interface FastEthernet1/0/2, changed state to up
*Mar  1 09:05:46.775: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/2, changed state to up
SW1#
*Mar  1 09:05:58.779: STP: VLAN0001 Fa1/0/2 -> learning
SW1#
*Mar  1 09:06:13.745: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
*Mar  1 09:06:13.770: STP: VLAN0001 Topology Change rcvd on Fa1/0/1
*Mar  1 09:06:13.787: STP[1]: Generating TC trap for port FastEthernet1/0/2
*Mar  1 09:06:13.787: STP: VLAN0001 Fa1/0/2 -> forwarding
*Mar  1 09:06:13.812: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1#
*Mar  1 09:06:37.770: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1#
*Mar  1 09:07:28.655: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1#
*Mar  1 09:08:47.810: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1#sh spa
SW1#sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    8193
             Address     e8ed.f315.9380
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    8193   (priority 8192 sys-id-ext 1)
             Address     e8ed.f315.9380
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1             Desg FWD 19        128.3    P2p 
Fa1/0/2             Desg FWD 19        128.4    P2p 


SW1#
*Mar  1 09:09:16.826: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#do sh ip int vlan 1
Vlan1 is up, line protocol is up
  Internet address is 172.16.0.11/24
  Broadcast address is 255.255.255.255
  Address determined by setup command
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Outgoing access list is not set
  Inbound  access list is not set
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF switching turbo vector
  IP Null turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
          
SW1(config)#
*Mar  1 09:11:23.377: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1(config)#
*Mar  1 09:13:10.591: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1(config)#
*Mar  1 09:13:39.608: STP: VLAN0001 Topology Change rcvd on Fa1/0/2
SW1(config)#
*Mar  1 09:15:30.245: STP: VLAN0001 heard root     1-0026.ca6b.e980 on Fa1/0/2
*Mar  1 09:15:30.245:     supersedes  8193-e8ed.f315.9380
*Mar  1 09:15:30.245: STP: VLAN0001 new root is 1, 0026.ca6b.e980 on port Fa1/0/2, cost 38
SW1(config)#
*Mar  1 09:16:59.475: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/2
SW1(config)#
*Mar  1 09:17:00.557: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/2
SW1(config)#
*Mar  1 09:17:02.562: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/2
SW1(config)#
*Mar  1 09:17:04.567: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/2
SW1(config)#
*Mar  1 09:17:06.571: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/2
SW1(config)#conf t
             ^
% Invalid input detected at '^' marker.

SW1(config)#spa
SW1(config)#spanning-tree loop
SW1(config)#spanning-tree loopguard defa
SW1(config)#no spanning-tree loopguard default 
SW1(config)#spa
SW1(config)#int range f1/0/1-2
SW1(config-if-range)#spa
SW1(config-if-range)#spanning-tree gu
SW1(config-if-range)#spanning-tree guard lo
SW1(config-if-range)#spanning-tree guard loop 
SW1(config-if-range)#^Z
SW1#
*Mar  1 09:21:01.947: %SYS-5-CONFIG_I: Configured from console by console
SW1#sh spa
SW1#sh spanning-tree vlan 1

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             Cost        38
             Port        4 (FastEthernet1/0/2)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    8193   (priority 8192 sys-id-ext 1)
             Address     e8ed.f315.9380
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1             Desg FWD 19        128.3    P2p 
Fa1/0/2             Root FWD 19        128.4    P2p 


SW1#
SW2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW2(config)#spa
SW2(config)#spanning-tree loo
SW2(config)#spanning-tree loopguard defa
SW2(config)#spanning-tree loopguard default 
SW2(config)#spa
SW2(config)#spanning-tree rootgu
SW2(config)#spanning-tree rootgua
SW2(config)#spanning-tree root   
SW2(config)#spanning-tree roo 
SW2(config)#spanning-tree roo
SW2(config)#spanning-tree gua
SW2(config)#spanning-tree por
SW2(config)#spanning-tree portfast gur
SW2(config)#spanning-tree portfast gua
SW2(config)#spanning-tree portfast roo
SW2(config)#spanning-tree portfast roogu
SW2(config)#spanning-tree portfast ?    
  bpdufilter  Enable portfast bpdu filter on this switch
  bpduguard   Enable portfast bpdu guard on this switch
  default     Enable portfast by default on all access ports

SW2(config)#spanning-tree gu       
SW2(config)#spanning-tree gur
SW2(config)#spanning-tree gua
SW2(config)#spanning-tree ro 
SW2(config)#spanning-tree lo
SW2(config)#spanning-tree lo
SW2(config)#spanning-tree l 
SW2(config)#spanning-tree loo
SW2(config)#spanning-tree rootgu    
SW2(config)#spanning-tree rootgu
SW2(config)#spanning-tree rootgu
SW2(config)#spanning-tree guard  
*Mar  1 08:58:10.553: set portid: VLAN0001 Fa1/0/1: new port id 8003
*Mar  1 08:58:10.553: STP: VLAN0001 Fa1/0/1 -> listening
SW2(config)#spanning-tree guard loot
*Mar  1 08:58:12.549: %LINK-3-UPDOWN: Interface FastEthernet1/0/1, changed state to up
*Mar  1 08:58:13.556: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/1, changed state to up
SW2(config)#spanning-tree guard root
                          ^
% Invalid input detected at '^' marker.

SW2(config)#
*Mar  1 08:58:25.560: STP: VLAN0001 Fa1/0/1 -> learning
SW2(config)#int f1/0/1
*Mar  1 08:58:40.567: STP[1]: Generating TC trap for port FastEthernet1/0/1
*Mar  1 08:58:40.567: STP: VLAN0001 sent Topology Change Notice on Fa1/0/2
*Mar  1 08:58:40.567: STP: VLAN0001 Fa1/0/1 -> forwarding
SW2(config)#int f1/0/3
SW2(config-if)#spa
SW2(config-if)#spanning-tree gu
SW2(config-if)#spanning-tree guard ro
SW2(config-if)#spanning-tree guard root 
SW2(config-if)#no spanning-tree guard root 
SW2(config-if)#exit
SW2(config)#no spa
SW2(config)#no spanning-tree loop
SW2(config)#no spanning-tree loopguard defau
SW2(config)#no spanning-tree loopguard default 
SW2(config)#int f1/0/3
SW2(config-if)#spa
SW2(config-if)#spanning-tree gu
SW2(config-if)#spanning-tree guard ro
SW2(config-if)#spanning-tree guard root 
SW2(config-if)#sp
SW2(config-if)#spa
SW2(config-if)#spanning-tree gua
SW2(config-if)#spanning-tree guard loo
SW2(config-if)#spanning-tree guard loop 
SW2(config-if)#no spanning-tree guard loop 
SW2(config-if)#^Z
SW2#
*Mar  1 09:01:11.788: %SYS-5-CONFIG_I: Configured from console by console
SW2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW2(config)#spa
SW2(config)#spa           
SW2(config)#spanning-tree loop
SW2(config)#spanning-tree loopguard defau
SW2(config)#spanning-tree loopguard default 
SW2(config)#^Z
SW2#
*Mar  1 09:01:54.419: %SYS-5-CONFIG_I: Configured from console by console
SW2#
*Mar  1 09:03:51.029: STP: VLAN0001 sent Topology Change Notice on Fa1/0/2
*Mar  1 09:03:51.029: STP[1]: Generating TC trap for port FastEthernet1/0/1
*Mar  1 09:03:52.036: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/1, changed state to down
SW2#
*Mar  1 09:03:53.043: %LINK-3-UPDOWN: Interface FastEthernet1/0/1, changed state to down
SW2#
*Mar  1 09:05:42.917: set portid: VLAN0001 Fa1/0/1: new port id 8003
*Mar  1 09:05:42.917: STP: VLAN0001 Fa1/0/1 -> listening
SW2#
*Mar  1 09:05:44.913: %LINK-3-UPDOWN: Interface FastEthernet1/0/1, changed state to up
*Mar  1 09:05:45.920: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet1/0/1, changed state to up
SW2#
*Mar  1 09:05:57.924: STP: VLAN0001 Fa1/0/1 -> learning
SW2#
*Mar  1 09:06:12.931: STP[1]: Generating TC trap for port FastEthernet1/0/1
*Mar  1 09:06:12.931: STP: VLAN0001 sent Topology Change Notice on Fa1/0/2
*Mar  1 09:06:12.931: STP: VLAN0001 Fa1/0/1 -> forwarding
SW2#
*Mar  1 09:15:29.406: STP: VLAN0001 heard root     1-0026.ca6b.e980 on Fa1/0/1
*Mar  1 09:15:29.406:     supersedes  8193-e8ed.f315.9380
*Mar  1 09:15:29.406: STP: VLAN0001 new root is 1, 0026.ca6b.e980 on port Fa1/0/1, cost 38
*Mar  1 09:15:29.842: STP: VLAN0001 sent Topology Change Notice on Fa1/0/1
*Mar  1 09:15:29.842: STP[1]: Generating TC trap for port FastEthernet1/0/2
*Mar  1 09:15:29.842: STP: VLAN0001 Fa1/0/2 -> blocking
SW2#
*Mar  1 09:16:58.636: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/1
SW2#
*Mar  1 09:16:59.718: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/1
SW2#
*Mar  1 09:17:01.723: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/1
SW2#
*Mar  1 09:17:03.728: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/1
SW2#
*Mar  1 09:17:05.733: STP: VLAN0001 heard root 32769-0022.bd89.2180 on Fa1/0/1
SW2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW2(config)#spa
SW2(config)#spanning-tree loop
SW2(config)#spanning-tree loopguard defau
SW2(config)#no spanning-tree loopguard default 
SW2(config)#int range f1/0/1-2
SW2(config-if-range)#spa
SW2(config-if-range)#spanning-tree gu
SW2(config-if-range)#spanning-tree guard lo
SW2(config-if-range)#spanning-tree guard loop 
SW2(config-if-range)#^Z
SW2#
*Mar  1 09:21:02.082: %SYS-5-CONFIG_I: Configured from console by console
SW2#
ASW1#sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    8193
             Address     e8ed.f315.9380
             Cost        19
             Port        1 (FastEthernet0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Root LRN 19        128.1    P2p 
Fa0/2               Altn BLK 19        128.2    P2p 
Fa0/3               Desg LIS 19        128.3    P2p 
Fa0/8               Desg LRN 19        128.8    P2p 


ASW1#sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    8193
             Address     e8ed.f315.9380
             Cost        19
             Port        1 (FastEthernet0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Root FWD 19        128.1    P2p 
Fa0/2               Altn BLK 19        128.2    P2p 
Fa0/3               Desg LIS 19        128.3    P2p 
Fa0/8               Desg FWD 19        128.8    P2p 


ASW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ASW1(config)#spa
ASW1(config)#spanning-tree loop
ASW1(config)#spanning-tree loopguard defa
ASW1(config)#spanning-tree loopguard default 
ASW1(config)#int f0/3
ASW1(config-if)#swi
ASW1(config-if)#spa        
ASW1(config-if)#spanning-tree guar
ASW1(config-if)#spanning-tree guard roo
ASW1(config-if)#spanning-tree guard root 
ASW1(config-if)#
*Mar  1 00:02:01.584: %SPANTREE-2-ROOTGUARD_CONFIG_CHANGE: Root guard enabled on port FastEthernet0/3.
ASW1(config-if)#
*Mar  1 00:02:27.631: %SPANTREE-2-ROOTGUARD_BLOCK: Root guard blocking port FastEthernet0/3 on VLAN0001.
ASW1(config-if)#sh sp
ASW1(config-if)#^Z   
ASW1#sh spa
ASW1#sh spanning-tree 
*Mar  1 00:03:39.764: %SYS-5-CONFIG_I: Configured from console by console
ASW1#sh spanning-tree inco
ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#
*Mar  1 00:03:45.787: %SPANTREE-2-ROOTGUARD_UNBLOCK: Root guard unblocking port FastEthernet0/3 on VLAN0001.
ASW1#                                   
*Mar  1 00:06:22.344: %SPANTREE-2-ROOTGUARD_BLOCK: Root guard blocking port FastEthernet0/3 on VLAN0001.
ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------
VLAN0001             FastEthernet0/3          Root Inconsistent

Number of inconsistent ports (segments) in the system : 1

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------

Number of inconsistent ports (segments) in the system : 0

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------

Number of inconsistent ports (segments) in the system : 0

ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------

Number of inconsistent ports (segments) in the system : 0

ASW1#
*Mar  1 00:08:08.569: %SPANTREE-2-ROOTGUARD_UNBLOCK: Root guard unblocking port FastEthernet0/3 on VLAN0001.
ASW1#sh spanning-tree inconsistentports 

Name                 Interface                Inconsistency
-------------------- ------------------------ ------------------

Number of inconsistent ports (segments) in the system : 0

ASW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ASW1(config)#int f0/3
ASW1(config-if)#no spa
ASW1(config-if)#no spanning-tree root
ASW1(config-if)#no spanning-tree gua 
ASW1(config-if)#no spanning-tree guard ro
ASW1(config-if)#no spanning-tree rootgu  
ASW1(config-if)#spa                    
ASW1(config-if)#spanning-tree roo
ASW1(config-if)#spanning-tree gua
ASW1(config-if)#spanning-tree guard ro
ASW1(config-if)#no spanning-tree guard root 
ASW1(config-if)#
*Mar  1 00:09:18.295: %SPANTREE-2-ROOTGUARD_CONFIG_CHANGE: Root guard disabled on port FastEthernet0/3.
ASW1(config-if)#do sh spa
ASW1(config-if)#do sh spanning-tree

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             Cost        19
             Port        3 (FastEthernet0/3)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 
Fa0/2               Desg LRN 19        128.2    P2p 
Fa0/3               Root FWD 19        128.3    P2p 
Fa0/8               Desg FWD 19        128.8    P2p 


ASW1(config-if)#do sh spanning-tree

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             Cost        19
             Port        3 (FastEthernet0/3)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 
Fa0/2               Desg LRN 19        128.2    P2p 
Fa0/3               Root FWD 19        128.3    P2p 
Fa0/8               Desg FWD 19        128.8    P2p 


ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 1, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 98
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 99
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 100
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 1, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 101
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 101
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 102
ASW1(config-if)#do sh spanning-tree int f0/3 detail
 Port 3 (FastEthernet0/3) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.3.
   Designated root has priority 1, address 0026.ca6b.e980
   Designated bridge has priority 1, address 0026.ca6b.e980
   Designated port id is 128.1, designated path cost 0
   Timers: message age 1, forward delay 0, hold 0
   Number of transitions to forwarding state: 3
   Link type is point-to-point by default
   Loop guard is enabled by default on the port
   BPDU: sent 201, received 103
ASW1(config-if)#do sh span

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             Cost        19
             Port        3 (FastEthernet0/3)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 
Fa0/2               Desg FWD 19        128.2    P2p 
Fa0/3               Root FWD 19        128.3    P2p 
Fa0/8               Desg FWD 19        128.8    P2p 


ASW1(config-if)#
*Mar  1 00:11:58.534: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
ASW1(config-if)#
*Mar  1 00:11:59.532: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to down
ASW1(config-if)#
*Mar  1 00:12:05.732: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
*Mar  1 00:12:06.738: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
ASW1(config-if)#do sh spann
ASW1(config-if)#do sh spann

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             Cost        19
             Port        3 (FastEthernet0/3)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0022.bd89.2180
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 
Fa0/2               Desg FWD 19        128.2    P2p 
Fa0/3               Root FWD 19        128.3    P2p 
Fa0/8               Desg FWD 19        128.8    P2p 


ASW1(config-if)#conf t
                 ^
% Invalid input detected at '^' marker.

ASW1(config-if)#exit
ASW1(config)#spa
ASW1(config)#spanning-tree loop
ASW1(config)#spanning-tree loopguard defau
ASW1(config)#spanning-tree loopguard default 
ASW1(config)#spa
ASW1(config)#spa           
ASW1(config)#int range f0/1-2 spa
ASW1(config)#int range f0/1-2    
ASW1(config-if-range)#spa
ASW1(config-if-range)#spanning-tree gu  
ASW1(config-if-range)#spanning-tree guard loo
ASW1(config-if-range)#spanning-tree guard loop 
ASW1(config-if-range)#^Z
ASW1#
*Mar  1 00:15:58.264: %SYS-5-CONFIG_I: Configured from console by console
ASW1#
ASW2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ASW2(config)#
ASW2(config)#
ASW2(config)#
ASW2(config)#
ASW2(config)#
ASW2(config)#
ASW2(config)#
ASW2(config)#spa
ASW2(config)#spanning-tree pri
ASW2(config)#spanning-tree vlan 1 pri
ASW2(config)#spanning-tree vlan 1 priority 0
ASW2(config)#int vlan 1
ASW2(config-if)#ip address 172.16.0.22 255.255.255.0
ASW2(config-if)#no shut
ASW2(config-if)#e
*Mar  1 00:03:04.205: %LINK-3-UPDOWN: Interface Vlan1, changed state to up
ASW2(config-if)#exit
ASW2(config)#
*Mar  1 00:03:04.213: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
ASW2(config)#spa
ASW2(config)#spanning-tree vla
ASW2(config)#spanning-tree vlan 1 pri
ASW2(config)#no spanning-tree vlan 1 priority 
ASW2(config)#do sh spa                        
ASW2(config)#do sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    8193
             Address     e8ed.f315.9380
             Cost        38
             Port        1 (FastEthernet0/1)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)
             Address     0026.ca6b.e980
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Root FWD 19        128.1    P2p 


ASW2(config)#do sh spanning-tree int f0/1

Vlan                Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
VLAN0001            Root FWD 19        128.1    P2p 
ASW2(config)#do sh spanning-tree int f0/1 deta
 Port 1 (FastEthernet0/1) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.1.
   Designated root has priority 8193, address e8ed.f315.9380
   Designated bridge has priority 32769, address 0022.bd89.2180
   Designated port id is 128.3, designated path cost 19
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type is point-to-point by default
   BPDU: sent 33, received 67
ASW2(config)#do sh spanning-tree int f0/1 deta
 Port 1 (FastEthernet0/1) of VLAN0001 is root forwarding 
   Port path cost 19, Port priority 128, Port Identifier 128.1.
   Designated root has priority 8193, address e8ed.f315.9380
   Designated bridge has priority 32769, address 0022.bd89.2180
   Designated port id is 128.3, designated path cost 19
   Timers: message age 2, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type is point-to-point by default
   BPDU: sent 33, received 68
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 33, received 71
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 33, received 71
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 33, received 71
ASW2(config)#do ping 172.16.0.11
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/2/8 ms
ASW2(config)#do ping 172.16.0.11
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/5/9 ms
ASW2(config)#do ping 172.16.0.11 repeat 1000000
Type escape sequence to abort.
Sending 1000000, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!.
Success rate is 99 percent (912/913), round-trip min/avg/max = 1/3/33 ms
ASW2(config)#spa
ASW2(config)#spanning-tree vla
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 33, received 117
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 33, received 119
ASW2(config)#spa                                       
ASW2(config)#spanning-tree vla
ASW2(config)#spanning-tree vlan 1 pri
ASW2(config)#spanning-tree vlan 1 priority 0
ASW2(config)#spanning-tree vlan 1 priority 0
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 34, received 125
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 35, received 125
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 35, received 125
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 49, received 125
ASW2(config)#do sh spanning-tree int f0/1 deta | i BPDU
   BPDU: sent 49, received 125
ASW2(config)#sh spa
ASW2(config)#sh spann
ASW2(config)#do sh spa
ASW2(config)#do sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    1      (priority 0 sys-id-ext 1)
             Address     0026.ca6b.e980
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 


ASW2(config)#do ping 172.16.0.11 repeat 1000000        
Type escape sequence to abort.
Sending 1000000, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
......
Success rate is 0 percent (0/6)
ASW2(config)#no spa
ASW2(config)#no spanning-tree vla
ASW2(config)#no spanning-tree vlan 1 pri
ASW2(config)#no spanning-tree vlan 1 priority 
ASW2(config)#do ping 172.16.0.11 repeat 1000000
Type escape sequence to abort.
Sending 1000000, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
........................!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.
Success rate is 95 percent (570/595), round-trip min/avg/max = 1/3/33 ms
ASW2(config)#do ping 172.16.0.11 repeat 1000000
Type escape sequence to abort.
Sending 1000000, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (804/804), round-trip min/avg/max = 1/4/42 ms
ASW2(config)#sh spa                            
ASW2(config)#spa   
ASW2(config)#spanning-tree vlan 1 pri
ASW2(config)#spanning-tree vlan 1 priority 0
ASW2(config)#
*Mar  1 00:11:41.027: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down
*Mar  1 00:11:42.025: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down
ASW2(config)#
*Mar  1 00:11:43.024: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to down
ASW2(config)#
*Mar  1 00:11:49.256: %LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
*Mar  1 00:11:50.263: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
ASW2(config)#^Z
ASW2#sh spa
ASW2#sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    1      (priority 0 sys-id-ext 1)
             Address     0026.ca6b.e980
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  15  sec

Interface           Role Sts Cost      Prio.Nbr Type
-------------------
*Mar  1 00:12:13.43 ---- --- --------- -------- --------------------------------
Fa0/1               Desg LRN 19        128.1    P2p 


ASW2#2: %SYS-5-CONFIG_I: Configured from console by console
ASW2#
*Mar  1 00:12:17.274: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
ASW2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ASW2(config)#do sh spa
ASW2(config)#do sh spanning-tree 

VLAN0001
  Spanning tree enabled protocol ieee
  Root ID    Priority    1
             Address     0026.ca6b.e980
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    1      (priority 0 sys-id-ext 1)
             Address     0026.ca6b.e980
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/1               Desg FWD 19        128.1    P2p 


ASW2(config)#do ping 172.16.0.11 repeat 10000
Type escape sequence to abort.
Sending 10000, 100-byte ICMP Echos to 172.16.0.11, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.
Success rate is 99 percent (893/894), round-trip min/avg/max = 1/5/1007 ms
ASW2(config)#

References

tech/network/cisco/stp/loopguard/loopguard.txt · Last modified: 2019/06/08 16:09 by wnoguchi