STP root bridge and Layer 2 Switch

[mahesh18]

Hi Everyone,

I have quick question about STP Root bridge

The device is not Cisco device

Sw1 is layer 2 switch with data vlan 10

Sw2 is layer 2 switch with multiple vlans

Sw3 is Core Layer 3 switch with Layer 3 interfaces for all  the vlan.

(Vlan 10 --- 10.10.10.20)

User PC IP 

10.10.10.21/24

GW 10.10.10.20

Topology

Sw1--------------trunk----sw2--------trunk-------sw3

if for some reason Sw1 becomes root bridge for vlan 10 instead of Sw3 will User PC able to ping the gateway?

We had issue today where Sw1 become root bridge with lower priority then SW3 and users were unable to ping the default gateway.

Regards

Mahesh

[Larry Sullivan]

Hi,

Sounds like you answered your own question, or at least the situation did.  Does SW1 have a default GW?  Also, why not prevent SW1 from ever becoming the root in the future? 

[mahesh18]

SW1 has default route to managment network only.

Topology change happened as someone from server team connected the server/switch to one of the ports on the SW1

[rais]

There aren't any loops in your L2 diagram. I wonder how would the topology change even if any of the switches becomes root.

Thanks.