два коммутатора (5505 и 2912) повязаны по оптике через конвертеры (FO-TP).
на 5505:
set port speed 4/11 100
set port duplex 4/11 full
set trunk 4/11 on dot1q 1-1005
на 2912
interface FastEthernet0/2
duplex full
speed 100
switchport trunk encapsulation dot1q
switchport mode trunk
spanning-tree portfast
и на 2912 происходит то ,что написано ниже
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 21 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 23 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 23 times per min
10w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 23 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 23 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 22 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 22 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to down
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 23 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 22 times per min
10w1d: %LINK-3-UPDOWN: Interface FastEthernet0/2, changed state to up
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 21 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 20 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 18 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 17 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 15 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 12 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 10 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 8 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 6 times per min
10w1d: %RTD-1-LINK_FLAP: FastEthernet0/2 link down/up 5 times per min
В чем может быть косяк?