crate vlan10 & vlan20 on 2 6509,connect one 2950 switch on Gi2/1(I use command "switchport access vlan 10") and Gi2/2 for another(swicthport access vlan 20)
Gi2/3 & Gi2/4 is EtherChannel to connect another 6509.
about spaining tree,I use "spaining-tree mode mst" on 6509 and I also use this command in 2 2950 switch
fastethernet port use spaining-tree portfast command,but I got a problem,when I disconnect EtherChannel link on cat6509,one 6509 switch's vlan 20 always done,and Gi2/2 spaining tree status is block,why??
what are the VLAN STP priorities for you VLANs ? Which switch is the root switch for which VLAN ? In general, when a port is blocked there is another one forwarding for the same VLAN. Can you post the configuration of your switches ?
two 2950 switch is not set priority so it is 32768,
normally,the spaining tree will blocked Gi0/2(connect to 6509-B),when I disconnect EtherChannel,it should be forwarding status for all link,right?I can see all switch port LED is green,but when I show vlan,the vlan 20 is down,and when show spaining-tree,6509-B's Gi2/2 is blocked,would you provide any experience to me?thank you