Cisco 1242-AG multicast and IPv6 weirdness

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This relates to at least IOS Version 12.4(10b)JDA3, RELEASE SOFTWARE (fc1) and Version 12.2(44)SE2, RELEASE SOFTWARE (fc2)

I had weird problems where Bonjour, Zeroconf, mDNS or whatever you'd like to call it doesn't work. I noticed the problem when things like Airplay would work for a few minutes when the device first associated, but would then disappear. Additionally, wireless hosts can acquire an IPv6 through SLAAC, yet no traffic is passed. However, a ping6 foo.bar.baz succeeds.

There are loads of people suggesting that disabling IGMP snooping would work:

$ en
# conf t
(config)# no ip igmp snooping 

But it doesn't.

The problem seems to be that the access point can only bridge multicast traffic to the native VLAN of its wired interface. Put everything in bridge-group 1 and it works fine, for example on my 1242 with both 802.11bg and 802.11a radios:

bridge 1 route ip
!
dot11 ssid whargarbl
 vlan 2
!
bridge irb
interface Dot11Radio0
 ssid whargarbl
!
interface Dot11Radio0.2
 encapsulation dot1Q 2
 bridge-group 1
!
interface Dot11Radio1
 ssid whargarbl
!
interface Dot11Radio1.2
 encapsulation dot1Q 2
 bridge-group 1
!
interface FastEthernet0.2
 encapsulation dot1Q 2 native 
 bridge-group 1
!
interface BVI1
 ip address w.x.y.z p.q.r.s
!

This works, but it's a bit disappointing. It means that the management IP address must be in line with the host traffic, and also that multicast bridging is only possible for one VLAN. Boo.