Anyone have a clue to what this is? On a sup720 6500
The static mac-address you are refering to is programmed in hardware automatically by the supervisor software. This is normal. That's reserved for IPv6's all-nodes multicast.
Have a look at
http://www.faqs.org/rfcs/rfc2464.html for more information.
To stop these from being learned, use
"no ipv6 mld snooping" in global configuration mode.
The learned entries should age out once that is configured and won't be relearned.
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