[156558] in North American Network Operators' Group
Re: Big Temporary Networks
daemon@ATHENA.MIT.EDU (Masataka Ohta)
Wed Sep 19 21:25:43 2012
Date: Thu, 20 Sep 2012 10:24:03 +0900
From: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
To: William Herrin <bill@herrin.us>
In-Reply-To: <CAP-guGUq4Pvh-wjo+piX5wOgMEsTXndTQJFRdm+zEHYR_78CZA@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
William Herrin wrote:
> 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. It's not
> unicast but its subject to error recovery anyway.
Mostly correct.
But, as I already wrote:
1) broadcast/multicast from a STA attacked to an AP is
actually unicast to the AP and reliably received by the
AP (and relayed unreliably to other STAs). That is, a
broadcast ARP request from the STA to the AP is reliably
received by the AP.
Because of hidden terminals, L2 broadcast/multicast is transmitted
only from AP.
>> However, at WiFi L2, it is first unicast to AP and then broadcast
>> by the AP.
>
> Your use of nomenclature is incorrect. It'd be like saying my ethernet
Ethernet?
> card unicasts a packet to the switch and then the switch broadcasts it
> out all ports. Or like saying that a packet with an explicit MAC
> destination
Do you know MAC header of 802.11 contains four, not just source
and destination, MAC addresses?
Because of hidden terminals and because of impossibility of
collision detection, WLAN is a little more complex than your
guess.
> No offense, but it is not for you or I or Owen Delong to declare that
> IPv6 is or isn't operational.
A single counter example is enough to deny IPv6 operational.
> whether and when IPv6 is sufficiently
> operational for their use.
The scope is not "their use" but "as a protocol for the entire
Internet".
Masataka Ohta
