Subject: [dhcwg] Proposed Resolution to DNA Issue 26

From: Bernard Aboba <[email-masked]>
Date: Wed, 1 Jun 2005 17:45:53 -0700 (PDT)

The text of DNA Issue 26 is enclosed below.  This comment was submitted
during IETF Last Call.  The proposed resolution is as follows:

1. Change the title to "Detecting Network Attachment"
2. No change. The goals of DNAv4 & DNAv6 are similar.
3. Include definition of "Point of Attachment", "Link Up" and "Link".
Change "Most Likely Point of Attachment" to "Most Likely Attachment
Network" to avoid confusion.  Also, change "valid address" to "operable
address for compatibility with RFC 3927 terminology.

Change Section 1.2 (Terminology) to the following:

"1.2.  Terminology

This document uses the following terms:

ar$sha
     ARP packet field: Source Hardware Address [RFC826]. The hardware
     (MAC) address of the originator of an ARP packet.

ar$spa
     ARP packet field: Source Protocol Address [RFC826].  For IP Address
     Resolution this is the IPv4 address of the sender of the ARP
     packet.

ar$tha
     ARP packet field: Target Hardware Address [RFC826].  The hardware
     (MAC) address of the target of an ARP packet.

ar$tpa
     ARP packet field: Target Protocol Address [RFC826].  For IPv4
     Address Resolution, the IPv4 address for which one desires to know
     the hardware address.

ARP Probe
     An ARP Request packet, broadcast on the local link, with an all-
     zero 'sender IP address' (ar$spa).  The 'sender hardware address'
     (ar$sha) MUST contain the hardware address of the interface sending
     the packet.  The 'target hardware address' field (ar$tha) is
     ignored and SHOULD be set to all zeroes.  The 'target IP address'
     (ar$tpa) field MUST be set to the address being probed.

ARP Announcement
     An ARP Request packet, broadcast on the local link, identical to
     the ARP Probe described above, except that both the sender (ar$spa)
     and target (ar$tpa) IP address fields contain the IP address being
     announced.

DHCP client
     A DHCP client or "client" is an Internet host using the Dynamic
     Host Configuration protocol (DHCP) [RFC2131] to obtain
     configuration parameters such as a network address.

DHCP server
     A DHCP server or "server" is an Internet host that returns
     configuration parameters to DHCP clients.

Link A communication facility or medium over which network nodes can
     communicate.  Each link is associated with a minimum of two
     endpoints.  Each link endpoint has a unique link-layer identifier.

Link Down
     An event provided by the link layer that signifies a state change
     associated with the interface no longer being capable of
     communicating IP packets.  A Link Down event is only generated once
     the link layer considers the link unusable; transient periods of
     high frame loss are not sufficient.  DNAv4 does not utilize "Link
     Down" indications.

Link Layer
     Conceptual layer of control or processing logic that is responsible
     for maintaining control of the data link.  The data link layer
     functions provide an interface between the higher-layer logic and
     the data link.  The link layer is the layer immediately below IP.

Link Up
     An event provided by the link layer that signifies a state change
     associated with the interface becoming capable of communicating IP
     packets.

Most Likely Attachment Network (MLAN)
     The attached network heuristically determined by the host to be
     most likely, based on hints.

Point of Attachment
     The link endpoint on the link to which the host is currently
     connected.

Routable address
     In this specification, the term "routable address" refers to any
     IPv4 address other than an IPv4 Link-Local address.  This includes
     private addresses as specified in [RFC1918].

Operable address
     In this specification, the term "operable address" refers to either
     a static IPv4 address, or an address assigned via DHCPv4 which has
     not been relinquished, and whose lease has not yet expired."

---------------------------------------------------------------------
Issue 26: IETF Last Call comments
Submitter name: JinHyeock Choi
Submitter email address: [email-masked]
Date first submitted: May 24, 2005
Reference:
Document: DNA-11
Comment type: T
Priority: S
Section: Various
Rationale/Explanation of issue:

I'd like to mention a few differences between DNA for IPv4 (DNAv4)
and DNA for IPv6 (DNAv6).

1. Abbreviation
For IPv4, DNA stands for "Detection of Network Attachment", whereas
for IPv6, DNA stands for "Detecting Network Attachment".

2. DNA Goal
I understand DNAv4 aims to detects movement (or lack of movement)
between subnets, and obtains (or continue to use) a valid IPv4
configuration.

DNAv6 aims to detect movement (or lack of movement) between links
to ascertain the validity of existing IP configuration but does not
include the actual IP configuration procedure.

3. Point of Attachment
In DNA mailing list, we define a term "Attachment Point", which represents
the link-layer connection.

For example, assume the case of two 802.11 b APs and a router on the same
ethernet link. Each AP is an Attachment Point and if a host moves from
one AP to another, it has moved to a different Attachment Point.

It's my impression that the "Attachment Point" from DNA WG and
"Point of Attachment" from the draft doesn't mean the same thing.

Also I am glad & relieved to see that the draft no longer includes the
term 'link identifier'. Though the draft still uses the term 'link' a few
times, the meaning is clear from the context.

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