Hi Thomas,
The 2nd paragraph of the current node requirements draft says
For those IPv6 Nodes (acting as hosts) that implement DHCP, those
nodes MUST use DHCP upon the receipt of a Router Advertisement with
the 'O' flag set (see section 5.5.3 of RFC2462). In addition, in the
absence of a router, hosts that implement DHCP MUST attempt to use
DHCP. For IPv6 Nodes that do not implement DHCP, the 'O' flag of a
Router Advertisement can be ignored. Furthermore, in the absence of
a router, these types of node are not required to initiate DHCP.
You said:
> For my tastes, there is too much protocol specification above (use of
> MUST language). Better to just cite the existing standards.
and:
For those IPv6 Nodes (acting as hosts) that implement DHCP, those
nodes should use DHCP upon the receipt of a Router Advertisement with
the 'O' flag set (see section 5.5.3 of RFC2462). In addition, in the
absence of a router, hosts that implement DHCP MUST attempt to use
DHCP. For IPv6 Nodes that do not implement DHCP, the 'O' flag of a
Router Advertisement can be ignored. Furthermore, in the absence of
a router, these types of node are not required to initiate DHCP.
> Perhaps because folk have forgotten about existing text in 2461 &
> 2462? :-)
>
> From section RFC 2461 6.3.7:
>
> > If a host sends MAX_RTR_SOLICITATIONS solicitations, and receives no
> > Router Advertisements after having waited MAX_RTR_SOLICITATION_DELAY
> > seconds after sending the last solicitation, the host concludes that
> > there are no routers on the link for the purpose of [ADDRCONF].
> > However, the host continues to receive and process Router
> > Advertisements messages in the event that routers appear
> on the link.
>
> RFC 2462, Section 5.5.2 says:
>
> > 5.5.2. Absence of Router Advertisements
> >
> > If a link has no routers, a host MUST attempt to use stateful
> > autoconfiguration to obtain addresses and other configuration
> > information. An implementation MAY provide a way to disable the
> > invocation of stateful autoconfiguration in this case, but the
> > default SHOULD be enabled. From the perspective of
> > autoconfiguration, a link has no routers if no Router Advertisements
> > are received after having sent a small number of Router Solicitations
> > as described in [DISCOVERY].
>
> We can debate whether the current text makes sense, but it reflects
> the thinking at the time...
The text I have is this, let me know if anyone has problems with the text. I have
tried to stay true to 2461 & 2462.
John
5.3.1 Managed Address Configuration
An IPv6 node that does not include an implementation of DHCP will be
unable to obtain any IPv6 addresses aside from link-local addresses
when it is connected to a link over which it receives a router
advertisement with the 'M' flag (Managed address configuration) set
and which contains no prefixes advertised for Stateless Address
Autoconfiguration (see section 4.5.2). In this situation, the IPv6
Node will be unable to communicate with other off-link nodes unless a
global or site-local IPv6 address is manually configured.
An IPv6 node that receives a router advertisement with the 'M' flag
set and that contains advertised prefixes will configure interfaces
with both stateless autoconfiguration addresses and addresses
obtained through DHCP.
For those IPv6 nodes that implement DHCP, those nodes should use DHCP
upon the receipt of a Router Advertisement with the 'M' flag set (see
section 5.5.3 of RFC2462) for address configuration. In addition,
in the absence of a router, IPv6 Nodes that implement DHCP MUST attempt
to use DHCP for address configuration.
5.3.2 Other Stateful Configuration
DHCP provides the ability to provide other configuration information
to the node. An IPv6 node that does not include an implementation of
DHCP will be unable to obtain other configuration information such as
the addresses of DNS servers when it is connected to a link over
which the node receives a router advertisement in which the 'O' flag
("Other stateful configuration") is set.
For those IPv6 Nodes (acting as hosts) that implement DHCP, those
nodes should use DHCP upon the receipt of a Router Advertisement with
the 'O' flag set (see section 5.5.3 of RFC2462) to obtain other
configuration. In addition, in the absence of a router, hosts that implement
DHCP MUST attempt to use DHCP. For IPv6 Nodes that do not implement DHCP, the
'O' flag of a Router Advertisement can be ignored. Furthermore, in the absence
of a router, these types of node are not required to initiate DHCP.
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