The exhibited network is stable and operating properly:
Assuming that default STP configurations are running on both switches, which port will be in blocking mode?
A.
Port Fa0/2 on Switch1
B.
Port Fa0/1 on Switch2
C.
Port Fa0/1 on Switch1
D.
Port Fa0/2 on Switch2
I think the C answer is not correct. A is correct. because the port f0/1 of switch 1 is lower port ! and STP will be block port f0/2 !
PLS comment???
Port Fa0/2 on Switch1 will be the root port, because of lower cost (100Mb/s – 19; 10Mb/s – 100).
@manh : you are wrong, due to F0/2 on both switches has higher bandwidth so they cannot blocked in this case, port with lower bandwidth will be considered for blocking, due to mac add of switch1 is higher than sw2 so F0/1 of switch2 will be actived ==> F0/1 of switch1 will be block, so C is correct answer
sw1
interface FastEthernet0/23
duplex half
speed 10
!
interface FastEthernet0/24
!
sw2
interface FastEthernet0/23
duplex half
speed 10
interface FastEthernet0/24
!
sw1#
Fa0/23 Altn BLK 100 128.23 Shr
Fa0/24 Root FWD 19 128.24 P2p
sw2#
Fa0/24 Desg FWD 19 128.24 P2p
Fa0/23 Desg FWD 100 128.23 Shr
sw2#
interface FastEthernet0/23
duplex half
speed 10
!
interface FastEthernet0/24
!
interface GigabitEthernet1/1
duplex full
speed 10
!
interface GigabitEthernet1/2
duplex full
speed 100
!
just for the heck of it
Interface Role Sts Cost Prio.Nbr Type
—————- —- — ——— ——– ——————————–
Gi1/1 Desg FWD 100 128.25 P2p
Gi1/2 Desg FWD 19 128.26 P2p
Fa0/24 Desg FWD 19 128.24 P2p
Fa0/23 Desg FWD 100 128.23 Shr
sw1#
interface FastEthernet0/23
duplex half
speed 10
!
interface FastEthernet0/24
!
interface GigabitEthernet1/1
duplex full
speed 10
!
interface GigabitEthernet1/2
duplex full
speed 100
!
Fa0/23 Altn BLK 100 128.23 Shr
Fa0/24 Root FWD 19 128.24 P2p
Gi1/1 Altn BLK 100 128.25 P2p
Gi1/2 Altn BLK 19 128.26 P2p
switch 2 has lowest mac address so it will be root bridge , all ports on root bridge will be in forward state, switch 1 fa0/2 has got low cost to reach switch 2 so it will be in forward state so fa0/1 in switch 1 will be in blocked state, ans is c
C.
Port Fa0/1 on Switch1
What Baswaraj is saying is correct. Pay attention to the link speeds. First is 10Mbps, second is 100Mbps.