The stupidity of trying to "fix" DHCPv6
jfbeam at gmail.com
Tue Jun 14 19:50:11 CDT 2011
On Tue, 14 Jun 2011 18:16:10 -0400, Owen DeLong <owen at delong.com> wrote:
> The point of /64 is to support automatic configuration and incredibly
> sparse host addressing.
> It is not intended to create stupidly large broadcast domains.
Several IETF (and NANOG) discussions say otherwise. While current
hardware doesn't handle thousands of hosts, the protocol was designed for
a future where that's not true. (there's a future where *everything* is
network enabled... microwave oven, doorbell, weed whacker, everything.)
> A /22 is probably about the upper limit of a sane broadcast domain, but,
> even with a /22
> or 1022 nodes max, each sending a packet every 10 seconds you don't get
> to 100s of PPS,
> you get 102.2pps.
As I said, DHCP isn't the only source of traffic. Setup a 1000 node
network today (just IPv4), and you will see a great deal of broadcast
traffic (unless those nodes aren't doing anything.) With IPv6, it's all
multicast (v6 doesn't have a "broadcast address") hinged on switches
filtering the traffic away from where it doesn't need to be. The
all-too-common Best Buy $20 white box ethernet switch does no multicast
filtering at all. Pretty much all wireless hardware sucks at multicast -
period. These are not things that can be fixed with a simple software
update... if the silicon doesn't do it, *it doesn't do it*.
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