Re: [mif] Review requested: draft-ietf-mif-dhcpv6-route-option

[Ted Lemon <[e-mail]>]

On Oct 30, 2011, at 1:02 PM, Alexandru Petrescu wrote:
The question one raised on 6man is about coexistence with RA about
default route.  One is aware that a similar situation (alternate
mechanism DHCP-vs-RA for default route) appeared recently when DNS-in-RA
was proposed (DHCP existed doing DNS).  RFC6106 proposes to  do
DNS-in-RA but has a section explaining coexistence with DHCP about DNS
address - and gives the latter precedence over.

This is a very good point, which should be addressed in the route option draft.   I think the right thing is to give RA precedence over DHCP for routing information, but am curious to know if others disagree.

In some cases this recommendation may be inappropriate - there may exist
cases where routing protocol software _and_ DHCP software should be used
on the same machine (e.g. use DHCP to get DNS address, and use OSPF to
do routing).  At that point it may be hard to prevent some particular
option of DHCP (route-option) being physically available on the machine.
Accidentally misconfiguration may happen.

Fortunately, this is not a very serious problem: the router and the DHCP server are both under control of the administrator, so they can simply configure them correctly, and the right thing will happen.   It is always possible, if the network administrator sets things up wrong, for the network to not work, and there is nothing the IETF can do to eliminate this risk.   Since the default case is for the network administrator not to configure DHCP, I think it's pretty safe to assume that we won't get a bad route configuration without some kind of positive action on the part of the administrator.