Big Temporary Networks

Mon Sep 17 01:03:29 UTC 2012


Masataka Ohta <mohta at necom830.hpcl.titech.ac.jp>: 

>Nick Hilliard wrote:
>
>>> Thus, protocols heavily depending on broadcast/multicast, such
>>> as ND, will suffer.
>> 
>> ok, you've trolled me enough to ask why ND is worse than ARP on a wavelan
>> network - in your humble opinion?
>
>Because, with IPv4:
>
>	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.
>
>	2) the AP knows MAC and IP addresses of STAs
>
>	3) ARP and DHCP replies are usually unicast
>
>ARP and DHCP usually work.
>
>For an unusual case of ARP for other STAs, collisions do
>increase initial latencies, but as refreshes are attempted
>several times, there will be no latter latencies.
>
>OTOH, IPv6 requires many multicast received by STAs: RA and NS
>for DAD, for example.
>
>Worse, minimum intervals of ND messages are often very large,
>which means a lot of delay occurs when a message is lost.
>
>							Masataka Ohta
>