Durante um dos labs no gns3 deparei-me com este erro, e com um write mem resolvi o problema :-D
Client(config)#vtp mode c Setting device to VTP CLIENT mode. % not enough space on flash to store vlan database. trying squeeze... squeeze of flash complete % not enough space on flash to store vlan database even after squeeze Client(config)#do wr mem Building configuration... [OK] Client(config)#vtp mode c Device mode already VTP CLIENT. Client(config)#