Optional-Spanning-tree-Features_3
STP BPDU Filter Default ・Filter BPDUs in and out
・If the port received BPDUs, immediately BPDU filter is disabled.
Verification Change interface e0/0 on SW2 to Routed Port. SW2
・e0/1 shut
・e0/0 L3 routed port IP address:169.254.24.2 /24
Set BPDU filter on global configuration mode
by using the command spanning-tree portfast bpdufilter default.
SW4(config)#spanning-tre portfast bpdufilter default SW4(config)#int e0/0 SW4(config-if)#shutdown SW4(config-if)#switchport mode access SW4(config-if)#switchport access vlan 10 SW4(config-if)#spanning-tree portfast SW4(config-if)#no shutdown SW4#sh spanning-tree summary Switch is in pvst mode Root bridge for: none Extended system ID is enabled Portfast Default is disabled Portfast Edge BPDU Guard Default is disabled Portfast Edge BPDU Filter Default is enabled Loopguard Default is disabled EtherChannel misconfig guard is enabled Configured Pathcost method used is short (omit)
SW4#sh span vlan 10 (omit) Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Et0/0 Desg FWD 100 128.1 Shr Et1/0 Root FWD 100 128.5 Shr Et1/1 Altn BLK 100 128.6 Shr SW4#sh span vlan 10 int e0/0 detail | i BPDU BPDU: sent 1, received 0 SW4#sh span vlan 10 int e0/0 detail | i BPDU BPDU: sent 5, received 0 SW4#sh span vlan 10 int e0/0 detail | i BPDU BPDU: sent 11, received 0 SW4#sh span vlan 10 int e0/0 detail | i BPDU BPDU: sent 11, received 0 SW4#sh span vlan 10 int e0/0 detail | i BPDU BPDU: sent 11, received 0 SW4#sh span vl 10 int e0/0 detail | i BPDU BPDU: sent 11, received 0 SW4#show spanning-tree vlan 10 int e0/0 detail Port 1 (Ethernet0/0) of VLAN0010 is designated forwarding Port path cost 100, Port priority 128, Port Identifier 128.1. Designated root has priority 4106, address aabb.cc00.0100 Designated bridge has priority 8202, address aabb.cc00.0400 Designated port id is 128.1, designated path cost 200 Timers: message age 0, forward delay 0, hold 0 Number of transitions to forwarding state: 1 The port is in the portfast edge mode Link type is shared by default Bpdu filter is enabled by default BPDU: sent 11, received 0
CCO describing "send a few BPDUs at link-up".
Specifically it seems to be 11 times. useful page ■Catalyst 3750-X and Catalyst 3560-X Switch Software Configuration Guide,
■Dive into CCIE
Changing e0/0 on SW2 to an access port . SW2(config)#default int e0/0 SW2(config)#int e0/0 SW2(config-if)#switchport access vlan 10 SW2(config-if)#switchport mode access SW2#clear spanning-tree counters SW2#sh spanning-tree int e0/0 detail Port 1 (Ethernet0/0) of VLAN0010 is designated forwarding Port path cost 100, Port priority 128, Port Identifier 128.1. Designated root has priority 4106, address aabb.cc00.0100 Designated bridge has priority 16394, address aabb.cc00.0200 Designated port id is 128.1, designated path cost 100 Timers: message age 0, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is shared by default BPDU: sent 7, received 0 SW2 sent BPDUs. SW4#sh span vl 10 int e0/0 detail Port 1 (Ethernet0/0) of VLAN0010 is root forwarding Port path cost 100, Port priority 128, Port Identifier 128.1. Designated root has priority 4106, address aabb.cc00.0100 Designated bridge has priority 16394, address aabb.cc00.0200 Designated port id is 128.1, designated path cost 100 Timers: message age 2, forward delay 0, hold 0 Number of transitions to forwarding state: 1 The port is in the portfast edge mode Link type is shared by default BPDU: sent 26, received 12 BPDU filter was disabled, so SW4 sent and recieved BDPUs. SW1#sh span vlan 10 (omit) Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Et0/0 Desg FWD 100 128.1 Shr Et0/1 Desg FWD 100 128.2 Shr Et1/0 Desg FWD 100 128.5 Shr Et1/1 Desg FWD 100 128.6 Shr Et1/3 Desg FWD 100 128.8 Shr SW2#sh spanning-tree vlan 10 (omit)
Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Et0/0 Desg FWD 100 128.1 Shr Et1/0 Root FWD 100 128.5 Shr Et1/1 Altn BLK 100 128.6 Shr SW3#sh spanning-tree vlan 10 (omit)
Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Et0/0 Root FWD 100 128.1 Shr Et0/1 Altn BLK 100 128.2 Shr Et1/0 Desg FWD 100 128.5 Shr Et1/1 Desg FWD 100 128.6 Shr SW4#sh spanning-tree vlan 10 (omit)
Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Et0/0 Root FWD 100 128.1 Shr Et1/0 Altn BLK 100 128.5 Shr Et1/1 Altn BLK 100 128.6 Shr This topology have not Loop.
