Ran into something I've never seen before in a production network I'm new to supporting and wanted to get the communities take on it.
I have an EIGRP network that interconnects about 60 sites across a Metro-E network. The sites use a /24 network and use VLAN 95 for communication. The EIGRP endpoints are mix of routers with sub-interfaces and switches with SVI's.
What I noticed is that some of the sites with switches have spanning-tree turned off for VLAN 95 (EIGRP VLAN) and some sites do. Further, I found an old 6000 series switch that has elected itself as the root bridge for VLAN 95.
What are the ramifications for this being off? I've never worked on any network where spanning-tree has been turned off. As far as I'm aware, spanning-tree being off causes MAC and broadcast instability but again, never seen this in production.
Should I turn it back on everywhere since it's essentially a connected Layer 2 VLAN EIGRP is using for L3 EIGRP transport or turn it off everywhere. Scratching my head here...