All,

Since our student body have returned, we've been seeing a trickle of:

%IPV6_ND-6-DUPLICATE_INFO: DAD attempt detected for FE80::5:73FF:FEA0:1 on VlanNNN

...on our Cisco 6500s. The vlan points to a bunch of Cisco WLC controllers running 7.4 and with all the IPv6 FHS turned on.

When I capture the packets (thanks for not logging the source MAC, Cisco!) I see it's coming from the MAC address of a couple of Android devices.

Source IP is :: dest is ff02::1:ffa0:1 (obviously) and the IP is a HSRPv2 virtual IP on the router itself.

So, two things:

1. Should the Cisco WLC IPv6 FHS stuff be blocking these, given the target IP is the HSRP VIP and is obviously not on a client? Do I need to be worried about them?

2. Where are they coming from? Is the client buggy and actually emitting the packet, or is it relaying these somehow from another network?

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