Re: WG ACTION: 1 week continued discussion [LL70] DNAv4 normative or informative?

I agree with Philip on every point.

Thanks,

	MikaL

On Wed, 2004-05-26 at 13:42, Philip Nye wrote:
> I support the principle that DNAv4 should become informative rather than normative - espescially as recent discussions here have shown that the reachability test of DNAv4 is a guide rather than a final and decisive test of the useability of an address.
> 
> I do not support the resolution text as it stands for several reasons:
> 
> 1. (editorial) an extra meaningless paragraph has appeared which is a combination of two others:
> 
> >    When an interface has a routable address configured on an interface,
> >    is based solely on the state of the interface, and is independent of
> >    any other protocols such as DHCP.  A host MUST NOT alter its behavior
> >    and use of other protocols such as DHCP because the host has assigned
> >    an IPv4 Link-Local address to an interface.
> 
> 2. (editorial) "When an interface has a routable address configured on an interface" needs to be changed. The paragraph should read:
> 
>    When a routable address is configured on an interface,
>    the host SHOULD NOT also assign an IPv4 Link-Local address to that
>    interface.
> 
> 3. (substantive) as I have said in previous discussion, the term "valid" carries meaning that is lost when it is simply dropped as here. I would rather keep the term "valid" (or "working" or "useable") and leave its definition fuzzy if necessary. I don't believe the proposed text adequately resolves this issue.
> 
>     If a host finds that an interface that was previous[ly] configured
>     with an IPv4 Link-Local address is now configured with a routable 
>     address, the host MUST use the routable address when initiating new 
>     communications...
> 
> I would interpret this text as a firm injunction preventing me from using IPv4LL on any interface which has a routable address however wrong and unuseable that address is. The only get out is weasle words about the meaning of "configured".
> 
> Philip
> 
> 
> ----- Original Message ----- 
> From: "Erik Guttman" <[email protected]>
> To: <[email protected]>
> Sent: Tuesday, May 25, 2004 4:56 PM
> Subject: WG ACTION: 1 week continued discussion [LL70] DNAv4 normative or informative?
> 
> 
> > LL70
> > 
> > This issue will remain open for comment until June 2, 2004.
> > After that point, if no comments are received, the issue will be
> > resolved by making DNAv4 normative and leaving the text as it currently
> > stands.
> > 
> > Bernard suggests the following resolution, which should allow DNAv4 to
> > remain an informative reference.
> > 
> > Was:
> > 1.9.  When to configure a Link-Local IPv4 address
> > 
> >    Having addresses of multiple different scopes assigned to an
> >    interface, with no adequate way to determine in what circumstances
> >    each address should be used, leads to complexity for applications and
> >    confusion for users.  A host with an address on a link can
> >    communicate with all other devices on that link, whether those
> >    devices use Link-Local addresses, or routable addresses.  For these
> >    reasons, a host SHOULD NOT have both a valid routable address and a
> >    Link-Local IPv4 address configured on the same interface.
> > 
> > 
> >    A routable address is any address that is:
> > 
> >    * a unicast address (see Section 1.2)
> >    * not a loopback address
> >    * not contained within the 169.254/16 prefix reserved for Link-Local
> >       IPv4 addresses
> > 
> >    A "valid routable address" is a routable address that passes the
> >    reachability test described in section 2 of "Detection of Network
> >    Attachment (DNA) in IPv4" [DNAv4].
> > 
> >    The assignment and use of a Link-Local IPv4 address on an interface
> >    is based solely on the state of the interface, and is independent of
> >    any other protocols such as DHCP.  A host MUST NOT alter its behavior
> >    and use of other protocols such as DHCP because the host has assigned
> >    a Link-Local IPv4 address to an interface.
> > 
> >    When an interface has a valid routable address configured on an
> >    interface, the host SHOULD NOT also assign a Link-Local IPv4 address
> >    to that interface.
> > 
> >    If a host finds that an interface that was previous configured with a
> >    Link-Local IPv4 address is now configured with a valid routable
> >    address, the host MUST always use the routable address when
> >    initiating new communications, and MUST cease advertising the
> >    availability of the Link-Local IPv4 address through whatever
> >    mechanisms that address had been made known to others.  The host
> >    SHOULD continue to use the Link-Local IPv4 address for communications
> >    underway when the routable address was configured, and MAY continue
> >    to accept new communications addressed to the Link-Local IPv4
> >    address.  Ways in which a valid routable address might be configured
> >    for the interface include:
> > 
> >    * Manual configuration
> >    * Address assignment through DHCP
> >    * Roaming of the host to a network on which a routable address
> >       assigned to the interface is valid
> > 
> >    If a host finds that an interface that was previously configured with
> >    a valid routable address no longer has a valid routable address, the
> >    host MAY identify a usable Link-Local IPv4 address (as described in
> >    section 2) and assign that address to the interface.  Ways in which a
> >    valid routable address might no longer be assigned to an interface
> >    include:
> > 
> >    * Removal of the address from the interface through manual
> >       configuration
> >    * Expiration of the lease on the address assigned through DHCP
> >    * Roaming of the host to a new network on which the address is no
> >      longer valid.
> > 
> >    Further discussion of the issues in detection of transient failures
> >    and the use of DHCP in response to network attachment failure is
> >    provided in "Detection of Network Attachment (DNA) in IPv4". [DNAv4]
> > 
> > 
> > 
> > Becomes:
> > 
> > 1.9.  When to configure an IPv4 Link-Local address
> > 
> >    Having addresses of multiple different scopes assigned to an
> >    interface, with no adequate way to determine in what circumstances
> >    each address should be used, leads to complexity for applications and
> >    confusion for users.  A host with an address on a link can
> >    communicate with all other devices on that link, whether those
> >    devices use Link-Local addresses, or routable addresses.  For these
> >    reasons, a host SHOULD NOT have both a routable address and an IPv4
> >    Link-Local address configured on the same interface.
> > 
> >    The assignment and use of an IPv4 Link-Local address on an interface
> >    is based solely on the state of the interface, and is independent of
> >    any other protocols such as DHCP.  A host MUST NOT alter its behavior
> >    and use of other protocols such as DHCP because the host has assigned
> >    an IPv4 Link-Local address to an interface.
> > 
> >    When an interface has a routable address configured on an interface,
> >    is based solely on the state of the interface, and is independent of
> >    any other protocols such as DHCP.  A host MUST NOT alter its behavior
> >    and use of other protocols such as DHCP because the host has assigned
> >    an IPv4 Link-Local address to an interface.
> > 
> >    When an interface has a routable address configured on an interface,
> >    the host SHOULD NOT also assign an IPv4 Link-Local address to that
> >    interface.
> > 
> >    If a host finds that an interface that was previous configured with
> >    an IPv4 Link-Local address is now configured with a routable address,
> >    the host MUST use the routable address when initiating new
> >    communications, and MUST cease advertising the availability of the
> >    IPv4 Link-Local address through whatever mechanisms that address had
> >    been made known to others.  The host SHOULD continue to use the IPv4
> >    Link-Local address for communications underway when the routable
> >    address was configured, and MAY continue to accept new communications
> >    addressed to the IPv4 Link-Local address.  Ways in which a routable
> >    address might be configured for the interface include:
> > 
> >    * Manual configuration
> >    * Address assignment through DHCP
> >   * Roaming of the host to a network on which the host has a
> >         valid routable address
> > 
> >    If a host finds that a routable address is no longer assigned to an
> >    interface, the host MAY identify a usable IPv4 Link-Local address (as
> >    described in section 2) and assign that address to the interface.
> >    Ways in which a routable address might no longer be assigned to an
> >    interface include:
> > 
> >    * Removal of the address from the interface through manual
> >       configuration
> >    * Expiration of the lease on the address assigned through DHCP
> >    * Roaming of the host to a new network on which the address is no
> >         longer valid.
> > 
> >    Further discussion of address assignment and the detection of network
> >    attachment is provided in [DNAv4].
> > 
> > Erik Guttman
> > ZEROCONF WG Chair
> > 
> >