I have a core switch 4500 connected to 7 sites using fiber cables, I have configured my vlans for the 7 sites, I started latey getting some trunk ports disabled in the 7 sites, show log was showing that I have some loop pack, for example
loopback error detected on Fa0/11, putting Fa0/11 in err-disable state.
can someone advise me what could be the reasons, is it some vkan configurations issues.
Core switch trunk example for one site
switchport access vlan 4
switchport trunk encapsulation dot1q
switchport mode trunk
also in my core switch i get this messages host is flapping between port G2/6 and G1/3
kindly advise if i miss any commands.