The stupidity of trying to "fix" DHCPv6

Ray Soucy rps at
Thu Jun 16 19:08:37 UTC 2011

Are you not using managed switches?

It takes me about 1 second to find exactly which device and which port
a device is connected to.  Once you know that; you have a pretty nice
collection of statistics and log messages that usually tell you
exactly what is wrong.

Or am I missing something?

On Thu, Jun 16, 2011 at 2:37 PM,  <sthaug at> wrote:
>> "Ethernet doesn't scale because of large amounts of broadcast traffic."
>> We started to introduce multicast, and multicast-aware switches in
>> IPv4; in IPv6 there is no broadcast traffic.  We won't be able to
>> scale networks up until we can turn off IPv4,
> In other words, probably not for another decade at least?
>> but once we can IPv6
>> will be able to grow much larger in terms of per-LAN.   The best
>> practice of no more than 512 per broadcast domain will seem very
>> outdated at that point; especially when you add in multicast flood
>> protection, the available bandwidth goes up, and performance of
>> network interfaces improves.
> Yes and no. If you remove the broadcast traffic you can *in theory*
> scale higher. However, this does nothing for the difficulty of L2
> troubleshooting, which is a real problem in large flat L2 networks.
>> The link you pointed to is talking about flat networks of tens of
>> thousands of hosts; that might be excessive right now...  But I can
>> certainly see an IPv6-only LAN (with some filtering to make sure ARP
>> and IPv4 traffic is dropped at the port) scaling easily to thousands
>> of hosts with today's hardware.
> I'm afraid I remain sceptical, unless we come up with significantly
> improved methods for L2 troubleshooting.
> Steinar Haug, Nethelp consulting, sthaug at

Ray Soucy

Epic Communications Specialist

Phone: +1 (207) 561-3526

Networkmaine, a Unit of the University of Maine System

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