Big Temporary Networks

William Herrin bill at herrin.us
Fri Sep 21 15:54:21 UTC 2012


On Thu, Sep 20, 2012 at 11:54 PM, Masataka Ohta
<mohta at necom830.hpcl.titech.ac.jp> wrote:
> Tony Hain wrote:
>> where an IPv6 multicast RA allows all the devices to
>> configure based on reception of a single packet.
>
> You miss multicast storm caused by DAD.

This is a long solved issue.

First, it already occurs with ARP broadcasts which the AP in principle
resends out to everybody else on the wlan.

Second, in the hotspot scenarios where this is likely to be a problem
(in IPv4 -or- IPv6) it's addressed by the "AP isolation" feature
that's getting close to omnipresent even in the low end APs. With this
feature enabled, stations are not allowed to talk to each other over
the wlan; they can only talk to hosts on the wired side of the lan.
The DAD packets are simply never sent to the other stations.

In theory there are some problems with this. In practice, it's in wide
deployment and has been demonstrated to work just fine.

Regards,
Bill Herrin

-- 
William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
Falls Church, VA 22042-3004



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