[142022] in North American Network Operators' Group
Re: The stupidity of trying to "fix" DHCPv6
daemon@ATHENA.MIT.EDU (sthaug@nethelp.no)
Thu Jun 16 14:37:43 2011
Date: Thu, 16 Jun 2011 20:37:12 +0200 (CEST)
To: rps@maine.edu
From: sthaug@nethelp.no
In-Reply-To: <BANLkTimRC5s3bSPaH7cV_oVa1f+=fW7i7oP+xg_q_W+JE8ediQ@mail.gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> "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 outdated at that point; especially when you add in multicast flood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@nethelp.no
