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Move the spanning-tree blocked ports

Posted on 2008-10-22
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Last Modified: 2008-10-24
Hello,

I have actually a loop of 2950 Series Switch (7 switchs in the loop), I implement spanning-tree pvst on each swith.
Then 1 port is blocked by spanning-tree, on the switch 5.
Whereas, I want to block the port 24 of the switch number 7. How can I do this, I suppose I can fix a cost. They have all 19 as cost  on FastEthernet and 4 for the Giga interface. (show spanning-tree)

Which procedure or command line can I use to fix the blocked port on a port I want.

Thanks in advance for your answer to my issue, it's urgent.
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Question by:croustimiel
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Expert Comment

by:from_exp
ID: 22784241
hi!
take a look here:
http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_example09186a00807b0670.shtml

specifically:
spanning-tree vlan 20,40,200 port-priority 64


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Expert Comment

by:rexxus
ID: 22785286
On switch 7, port 24 (if this is the uplink you want to block on) you want to increase the spanning tree port cost so that it blocks on that uplink, use:

spanning-tree cost 200
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harbor235 earned 500 total points
ID: 22785971


Port cost will change the port cost for all vlans, remember, PVST is a seperate spanning tree for each vlan.
If you want to manipulate the spanning tree on a per vlan basis then you can use the following;

Also rememeber, that all costs are configured from interface config mode;

switch# config t
switch#(conf) int X
switch#(conf-int) spanning-tree vlan X cost Y

There are default costs for each port type;


100 Mbit/s 19
155 Mbit/s 14
200 Mbit/s 12
622 Mbit/s 6
1 Gbit/s 4
2 Gbit/s 3
10 Gbit/s 2

harbor235 ;}
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