3com 2928 sfp vlans on fiber uplinks

[zeuxnet]

Hi to everybody...

I have a 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, all ports are set as hybrid

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
All ports are set as hybrid


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
All ports are set as hybrid

The port 25 of switch n.1 is connected to port 25 of switch n.3
The port 26 of switch n.1 is connected 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 correctly!

Please help me....

 

[VinceWhirlwind]

As VLAN400 isn't extended to Switch 3, this would appear to be a complete mystery.

Assuming the VLAN config is definitely all there as you describe, I would start with Switch1 config, in full, and go through it line by line to make sure I understand everything it is configured with.

What if you put Switch1, port23 in VLAN400 and put your host in that port instead - does the connection of Switch3 to the network still affect the ability of those hosts to ping each other?

 

[zeuxnet]

The problem was the MSTP. I disable it and now ping works...

Now I added a vlan (1800) on switch n.1 and n.3. On switch n.3 I added also a Vlan-interface for vlan 1800. The ip of the Vlan-interface1800 is 192.168.80.1.

So the switch n.3 has 3 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)
1800 tagged for port 25 (fiber) (192.168.80.0)
Vlan-Interface200 with ip 192.168.2.1
Vlan-interface1800 with ip 192.168.80.1
All ports are set as hybrid


The switch n.1 has 3 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)
1800 tagged AND PVID for port 22 and only tagged for port 25 (fiber) (192.168.80.0)
No Vlan-interface, all ports are set as hybrid


Now I can ping from client plugged on port of vlan 200 (192.168.2.0) of switch n.3 to client plugged on port 22 (vlan 1800) of the switch n.1 and viceversa.
But I can't ping from client plugged on port of vlan 200 of switch n.1 to client plugged on port 22 (vlan 1800) of the same switch.

Traceroute shows:
1. 1ms 1ms 1ms 192.168.2.1
2. * * * and so on...

the switch n.3 doesn't route the packets....Why?

Thanks very much....

 

[VinceWhirlwind]

Start with the client on port 22 - can it ping its default GW?