v6 subnet size for DSL & leased line customers

Stephen Sprunk stephen at sprunk.org
Wed Dec 26 02:05:12 UTC 2007

Thus spake <sthaug at nethelp.no>
>> In places where you need tighter control over the usage of various
>> gateways on a common L2 segment, VRRP probably makes more
>> sense.  However, as things currently stand, that means static routing
>> configuration on the host since for reasons passing understanding,
>> DHCP6 specifically won't do gateway assignment.
> For those of us with lots of IPv4 customers dependent on DHCP, it
> would be good to know more detail about this point. What is the
> problem, and are there plans to do anything about it in DHCPv6?

For most hosts, there is no need for anything like VRRP or getting a default 
gateway via DHCP in v6 because all hosts are required to implement RA/RS. 
The vast majority of hosts either have one default gateway or two-plus 
equivalent ones, so that works fine.  For hosts with multiple gateways that 
are unequal, VRRP+DHCP doesn't solve the problem any better than RA/RS; you 
have to fiddle with the hosts' routing tables to get things set up right.


Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking 

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