3com 2928 and fiber uplinks

[zeux]

Hi again to everybody...

 

I have another problem with 3com switch (2928 sfp)

 

Switch n.1 (2928) : 2 Vlans:

200 tagged and PVID for port 1-8, 25 (fiber) (192.168.2.0)

400 tagged and PVID for port 24, 26 (fiber) (192.168.4.0)

No Vlan-interface

 

Switch n.2 (2928): 2 Vlans:

100 tagged and PVID for port 1-8 (192.168.1.1)

400 tagged and PVID for port 10, 25 (fiber) (192.168.4.0)

Vlan-interface100 with ip 192.168.1.1

Vlan-interface400 with ip 192.168.4.1

 

 

Switch n.3 (2928): 2 Vlans:

100 tagged and PVID for port 17-20 (192.168.1.0)

200 tagged and PVID for port 1-16, 25 (fiber) (192.168.2.0)

Vlan-Interface200 with ip 192.168.2.1

 

The port 25 of switch n.1 is linked to port 25 of switch n.3

The port 26 of switch n.1 is linked to port 25 of switch n.2

 

Now I can't ping from a client connected to port 10 on switch 2 (vlan 400) to a client connected to port 24 on switch 1 (vlan 400). But if i disconnect the link between port 25 on switch 1 and port 25 on switch 3, the ping works perfectly!!! Why?

 

Insted ping between clients on vlan 200 on switches 1 and 3 works perfectly!

 

Please help me....