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Catalyst 2900 XL

Hi ,

I'm testing in a lab environnement a Cat 4006 with supp eng III with 2 switch 3550 and one 2900 xl connect to it .. I've configured the stp load balancing between the Giga port and a Fa port .. as follow

spanning tree Vlan 1 port-priority 100 ( Giga)

Spanning tree vlan 1 cost 4 (Giga)

Spanning tree clan 1 port-priority 125 (FA)

spanning tree vlan 1 cost 10 ( fa )

So like that I've got a failover ..

My question is when I do a Sh spanning-tree int ... on the 3550 switch I can see the port FA as BLOKED but on the 2900 XL switch both port are forwarding .. '?? So I do not know if the failover can work ..

Thank for your Help

Marc Chbaloz


Re: Catalyst 2900 XL


1) you can't do STP load balancing in one VLAN. STP load balancing is always meant as load balancing between trunks. Example: VLAN1 traffic sent on int fa 0/1 while VLAN2 traffic sent on fa 0/2. The only one port per switch is a root port for each VLAN.

See for details.

2) What is your network exact topology? Who's the root? Without knowing it it's impossible to say why on the 2900 XL switch both port are forwarding.



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