{SPAM?} Re: IPv6 Deployment for the LAN

[cra at WPI.EDU (Chuck Anderson)]

On Thu, Oct 22, 2009 at 03:57:40PM -0400, Ray Soucy wrote:
> Really.  How do we deal with rouge DHCP on the wireless LAN, obviously
> this is such a complex issue that we couldn't possibly have a solution
> that could be applied to RA.

Rogue DHCP doesn't immedately take down the entire subnet of machines 
with existing DHCP leases.  It generally only affects new machines 
trying to get a lease, or RENEWing machines.  The impact of a rogue RA 
is to immediately break connectivity for every machine on the subnet.  
Differing impacts leads to different risk assessments of which 
protocol to use.

Regardless, modern wireless deployments use central controllers or 
smart APs that can filter DHCP.  They could be extended to filter RA 
as well.

And this whole point is rather moot because we have RAs and must deal 
with them.  It is too late to get rid of the RA behavior of clients.  
Even if you don't want to use RAs, your hosts are going to still 
listen to them which means a Rogue RA is going to take down your 
network.  We have this problem even on IPv4-only subnets, where a 
Rogue RA (usually a Windows box with routing turned on) breaks 
connectivity to dual-stack servers for machines on that subnet.  Since 
the hosts prefer native IPv6 connectivity over IPv4, the hosts end up 
preferring the Rogue RA as the route towards the dual-stack server.

We really just need to bug our vendors to implement Rogue RA 
protection for wired and wireless ASAP, wherever we are in our 
deployment of IPv6.