On Thu, 2012-06-07 at 16:42 -0400, Ricky Beam wrote: > On Wed, 06 Jun 2012 17:17:37 -0400, Karl Auer wrote: > > a) DAD only happens when an IPv6 node is starting up. ARP happens > > whenever a node needs to talk to another node that it hasn't seen in > > while. > > DAD is a special case of ND. It happens every time the system selects > an address. (i.e. startup with non-SLAAC address, and when privacy > extensions generates an address.)
Er - OK. I should have said "happens when an address is assigned to an interface". It is still, however, way less traffic than ARP, which was my point. Possible exception - a network where everyone is using privacy addresses. > > b) DAD only goes to solicited node multicast addresses > > This assumes a network of devices that do multicast filtering, > correctly. Yes, it does. It assumes a properly provisioned and configured IPv6 network. While that may not be common now, it will become more common. And it is a self-correcting problem - people who don't want lots of noise will implement their networks correctly, those who don't care will do as they wish. No change there :-) BTW, I'm assuming here that by "multicast filtering" you mean "switching that properly snoops on MLD and sends multicast packets only to the correct listeners". > > c) Similarly, ND (the direct equivalent of ARP) goes only to > solicited node multicast addresses, ARP goes to every node on the > link. > > Effectively the same as broadcast in the IPv6 world. If everyone is > running IPv6, then everyone will see the packet. (things not running > ipv6 can filter it out, but odds are it'll be put on the cable.) On this point I think you are wrong. Except for router advertisements, most NDP packets are sent to a solicited node multicast address, and so do NOT go to all nodes. It is "the same as broadcast" only in a network with switches that do not do MLD snooping. > > So I'm not sure how DAD traffic would exceed ARP traffic. > > I wouldn't expect it to. Nor would I - which was the point of my response to an original poster who said it might. Regards, K. -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Karl Auer (ka...@biplane.com.au) http://www.biplane.com.au/kauer GPG fingerprint: AE1D 4868 6420 AD9A A698 5251 1699 7B78 4EEE 6017 Old fingerprint: DA41 51B1 1481 16E1 F7E2 B2E9 3007 14ED 5736 F687
