All I'm saying is that it's generally a bad idea to have different standards for "accidental" and "malicious" traffic. Say you were using DHCPv6 for routing; a malicious user could still inject traffic on the network to disrupt service. People get all uppity about RA because vendors have been painfully slow to implement RA Guard. To be fair, RA Guard probably should have been an early RFC as it was an obvious concern even at the time ICMPv6 was being drafted. I for one look forward to the day where things like RA Guard and MLD Snooping are standard on every switch. Just IPv6 growing pains. Also agree that I want flexibility to use RA or DHCPv6; the disagreement is that RA needs to be removed or changed from IPv6. Don't go breaking my IPv6 stack for your own ambitions, please. On Fri, Jun 10, 2011 at 10:28 AM, Leo Bicknell <bicknell@ufp.org> wrote:
In a message written on Fri, Jun 10, 2011 at 04:08:06PM +0200, Iljitsch van Beijnum wrote:
Ok, so now we've identified the problem.
How exactly does adding default gateway information to DHCPv6 solve this problem?
Please go back and re-read my original scenario and think about it.
The difference here is that if a client gets a DHCP address it generally won't be broken until it tries to renew, and then often won't be broken at renewal because it sends a directed request back.
In specific technical terms: DHCP relies on broadcast _ONCE_ at boot, and then uses static unicast config to verify that is still the correct config. RA's use broadcast every few seconds to broadcast new information that everyone is supposed to "trust" instantly.
Turn up a Rogue DHCP server on one of your subnets. It won't affect anyone who's already up and running. It may grab newly booted machines, depending on a race condition, but it won't break anything that is already working.
Turn up rogue RA's, and everyone instantly fails.
The behavior of these protocols is different, which leads to different failure modes. My assertion is that in every failure mode you can come up with RA's lead to more clients being down faster and for longer periods of time.
-- Leo Bicknell - bicknell@ufp.org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/
-- Ray Soucy Epic Communications Specialist Phone: +1 (207) 561-3526 Networkmaine, a Unit of the University of Maine System http://www.networkmaine.net/