nanog mailing list archives

Re: Big Temporary Networks


From: Masataka Ohta <mohta () necom830 hpcl titech ac jp>
Date: Sat, 22 Sep 2012 11:42:08 +0900

William Herrin wrote:

You miss multicast storm caused by DAD.

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

As you stated

: I think Masataka meant to say (and said previously) that the DHCP
: request from the wifi station is, like all packets from the wifi
: station to the AP, subject to wifi's layer 2 error recovery.

that is not a problem for IPv4 ARP and DHCP.

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.

You are saying to disable DAD, which is a violation of SLAAC.

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

Tell it to IETF to modify SLAAC to exclude DAD.

                                                Masataka Ohta



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