v6 & DSL / Cable modems

Jack Bates jbates at brightok.net
Fri Feb 6 20:37:00 UTC 2009

David W. Hankins wrote:
> What most people do of course is VRRP.

I agree, and I have done this in the past. However, I am very happy with 
the support of IPv6 to do away with requiring VRRP.

> Barring that, you just specify multiple default routers, and the
> client will select the router that still responds to ARP.  But
> support for this is not universal, so.

Always a problem, though arp doesn't timeout when a end node disappears 
in a reasonable fashion.

> When that isn't available, what I have done in the past here is to use
> the DHCP server to give out a default router option that is sorted
> according to the DHCP relay agent that was used to reach the server
> (keyed on giaddr contents).

This is a nice method as well, though limited by the half life of the 
DHCP lease. It also doesn't address the fact that you might be handing 
out IP addresses from *both* DHCP relay agents with cross redundancy for 

> No need to take on 'routed -q' in the client, it can stay a simple
> dumb host, with all configuration complexity in the DHCP server or
> negotiated in HA by the routers.

Dumb hosts is exactly what makes life infuriating. I want smart hosts. 
The network should be relatively dumb. Perhaps I'm mistaken, but the 
premise of IP was that hosts are smart and networks are dumb. Then we 
started making smart networks to break things.

I want built in multiple IP bindings on my hosts. I'd like (Windows 7 
without having to call netsh, perhaps?) support for static and dynamic 
addresses (privacy extensions are beautiful). I especially want support 
for multiple dynamic addresses with communication to the host that it 
should start using a newer address for future requests, yet finish up 
what it's doing with the old address before unbonding it.

Please don't get me wrong. I don't run a corporate network. I have my 
own little server farm and I have support to edge customers. What 
customer's do with the prefixes I give them is up to them. DHCP/SLAAC, 
it's all good. I'd rather not run DHCP for my servers or my little 
helpdesk network. On a standard ISP edge, I expect to see hybrid 
solutions; depending on the layout.


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