Spanning-tree uplink fast

[Ech]

Tôi có hai con switch kết nối qua 2 cổng Etherrnet. Liệu tôi có thể enable uplink fast được ko? Tôi test thử nhưng có vể nó ko hoạt động theo ý mình.


Cat3560#sh run | in uplink
spanning-tree uplinkfast

Cat3560#sh spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 20481
Address 000b.4610.e380
Cost 19
Port 8 (FastEthernet0/7)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 20481 (priority 20480 sys-id-ext 1)
Address 001c.b0d9.0280
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/7 Root FWD 19 128.8 P2p
Fa0/8 Altn BLK 19 128.9 P2p

Cat3560#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Cat3560(config)#int fa0/7
Cat3560(config-if)#shut
Cat3560(config-if)#
02:58:23: STP: VLAN0001 new root port Fa0/8, cost 19
02:58:23: STP: VLAN0001 Fa0/8 -> listening
02:58:24: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down
02:58:25: %LINK-5-CHANGED: Interface FastEthernet0/7, changed state to administratively down
02:58:25: STP: VLAN0001 sent Topology Change Notice on Fa0/8
02:58:26: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/7, changed state to down
02:58:38: STP: VLAN0001 Fa0/8 -> learning
02:58:53: STP: VLAN0001 Fa0/8 -> forwarding
02:58:54: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up

[Ech]

Theo quyen CCNP BCMSN Official Exam Certification Guide, Fourth Edition David Hucaby thì tôi có thể enable uplink fast ngay cả đối với trường hợp 2 switch connected back to back via 2 Ethernet links như trường hợp của tôi, vậy mà ... hu hu :(

TIP Many Catalyst switches have two built-in, high-speed uplink ports (Gigabit Ethernet,
for example). You might get the idea that UplinkFast can only toggle between two leaf-node
uplink ports. This is entirely untrue. UplinkFast keeps a record of all parallel paths to the Root
Bridge. All uplink ports but one are kept in the Blocking state. If the Root Port fails, the uplink
with the next-lowest Root Path Cost is unblocked and used without delay.