We have a network consisting of 30+ 3550 and 3750 switches which each connect back to 2 6509's, both with MSFC's.
Each wiring closet has it's own L2 VLAN with routing taking place on the 6509 MSFC. Some VLAN's are trunked to all the Wiring Closets for various reasons (most noteably the LWAPP vlan's for our LWAPP WLAN)
Earlier today multiple switches were disconnected from the network because their GBE uplink ports went into error disable. We can't pinpoint the reason for this (there were no changes made to the network) and the only clue I can find is that around the same time one of the 6509's sent the message "IGMPV3: Disabling IGMPV3 processing since MMLS was enabled on MSFC" to the syslog server.
My initial reaction is that there's a spanning tree problem or possibly a loop on the network. This was further backed up by the fact that many devices also complained about duplicate IP Addresses being identified.
Can anyone explain what the IGMPV3 message is and why it might occur?