I have an situation that I need advice/input on.
There are 25 switches in a building all Cisco.
At the core of the network is a stack of 7 Catalyst 3750's which have EtherChannel uplinks to all the outer switches.
The core switch also serves as the default gateway for all servers and pc's via the Vlan1 SVI (ip routing is enabled), the 3750 only has a single SVI (the default Vlan1 interface).
Some of the edge switches also perform L3 routing between two SVI's (1 is the default Vlan1 interface the other is a SVI for a voice vlan, vlan xx).
All of the switches apart from 3 are in the same VTP domain and are running PVST (configuration is default, priorities are default).
The switches at the edge of the network are connected as below based on being grouped in seperate rooms/floors:
Switch 1 -> Core
Switch 1 -> Switch 2
Switch 2 -> Switch 3
Switch 3 -> Core
In terms of STP the Core switch is the STP Root Bridge for all VLAN's apart from Vlan1, the Vlan 1 root bridge is a switch hanging off the Core that is in a seperate VTP domain but has a lower mac-address among VLAN1 switches so naturally has been elected root bridge.
I had an issue the other day with a switch that was part of a configuration similar to my Room 1 description above, I rebooted the switch and during the reboot it seemed to cause an STP Loop as the entire network went offline for the best part of a few minutes.
Is this likely to be a symptom of the way the network is configured in terms of STP?
From what I understand the core switch should be the STP Root Bridge when all other switches link back to it, in terms of PVST is there a set criteria for designating a root bridge for each vlan or should it just be the core switch as root for every Vlan?
If any of the above doesn't make sense which is quite likely please ask me for clarification: