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.LP
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.ds LF \fI\*(aR/\*(cA\fP
.ds RF \fICopyright 2006 Sun Microsystems, Inc.\fP
.if n .ds CF
.IP \fBSubject:\fP 15
IP Duplicate Address Detection
.IP "\fBSubmitted by:\fP" 15
James D. Carlson
.IP \fBFile:\fP 15
\*(aR/\*(cA/opinion.ms
.IP \fBDate:\fP 15
August 8th, 2006
.IP "\fBCommittee:\fP" 15
Bill Sommerfeld,
James D. Carlson,
Ed Gould,
Glenn Skinner,
Gary Winiger,
Shudong Zhou.
.IP "\fBProduct Approval Committee:\fP" 15
Solaris PAC
.br
solaris-pac-opinion@sun.com
.pn 2
.NH
Summary
.LP
This project proposes to make several infrastructural improvements to
how Solaris's IPv4 ARP and IPv6 Neighbor Discovery implementations
detect and handle situations where two nodes on a network claim the
same IP address.  This work will enable several follow-on projects in
the general area of dynamic network autoconfiguration.
.NH
Decision & Precedence Information
.LP
This project is approved as specified in reference [1].
.LP
The project may be delivered in a Patch/Micro release of Solaris
.bp
.NH
Interfaces
.LP
The project exports the following interfaces.
.if n .ne 8
.if t .ne 3
.TS H
box;
c s s
l | l | l.
Interfaces Exported
_
Interface	Classification	Comments
_
.TH
IPv6 DAD probing	Committed	RFC 2462
IPv4 DAD probing	Committed	RFC 3927 [1]

T{
Ongoing address defense behavior
T}	Committed

T{
UnARP (listen-only)
T}	Committed	RFC 1868

T{
kernel warning messages
T}	Uncommitted	arp(7P)

new ndd parameters	T{
Project Private
T}

arp(1M) "permanent" flag	Committed
arp(1M) output	Uncommited	[4]
ATF_AUTHORITY	Committed

ifconfig up/down	Committed
IFF_DUPLICATE	Committed	[2]
IFF_UP behavior	Committed
IFF_NOLOCAL behavior	Committed
rtsock DAD delay	Committed
AR_* STREAMS messages	T{
Consolidation Private
T}
DHCP PRE_BOUND state	Project Private	[3]
.TE
.IP 1
As revised to add ongoing address defense in the event of a collision;
see below.
.IP 2
New output-only flag; also visible in ifconfig output
.IP 3
New state; visible in ifconfig dhcp status output
.IP 4
Flag output changed to match command line keywords
.bp
.LP
The project imports the following interfaces.
.if n .ne 8
.if t .ne 3
.TS H
box;
c s s
l | l | l.
Interfaces Imported
_
Interface	Classification	Comments
_
.TH
ire_cache_lookup	T{
Consolidation Private
T}	kernel function
ire_refrele	T{
Consolidation Private
T}	kernel function
.TE
.NH
Opinion
.LP
.NH 2
Never give up, never surrender!
.LP
The Duplicate Address Detection algorithm described in RFC 3927 is
designed for the allocation of a randomized link-local IPv4 addresses,
and thus will back off (and pick a new address) in the event of a
collision.  This algorithm is inappropriate when applied to
authoritatively assigned addresses (i.e., manual assignment or DHCP)
as it renders the host subject to a difficult-to-diagnose "drive by"
denial-of-service attack.  If a duplicate is detected, rather than
giving up on a particular address forever, we instead back off for a
time and try again later.
.NH 2
Logging on both parties in the event of a conflict
.LP
In the event that a conflict is detected between two systems with this
project installed, warning messages logged on each system will contain
the layer-2 addresses of the other system, permitting any conflict to
be diagnosed starting from either system.
.NH 2 
Need efficient PRNG for protocol use.
.LP
Most protocols involving periodic broadcast messages will
self-synchronize unless timers have substantial random jitter added.
The Solaris kernel contains several common random number generator
functions; however, they are designed for cryptographic use and are
thus computationally expensive per bit generated.  A lighter weight
function would be useful both for this protocol and several other
projects; see the Advisory information below.
.NH
Minority Opinion(s)
.LP
None
.NH
Advisory Information
.LP
.RS
.IP 1.
The Solaris PAC should prioritize the establishment of a project to
provide a high-efficiency common random number generator for
non-cryptographic use (for instance, for adding random variability to
protocol timers to avoid self-synchronization).
.IP 2.
Once this project integrates and begins to be used on Sun's internal
network, the project team should make the operators of the network
aware of the new behavior in the event that there is unexpected
adverse behavior.
.RE
.NH
Appendices
.NH 2
Appendix A: Technical Changes Required
.LP
None.
.NH 2
Appendix B: Technical Changes Advised
.LP
None.
.NH 2
Appendix C: Reference Material
.LP
Unless stated otherwise, path names are relative to the case
directory \*(aR/\*(cA.
.IP 1.
Solaris IP Duplicate Address Detection, version 1.6
.br
File: final.materials/dad-design.pdf
.IP 2.
RFC 1868 UnARP
.br
http://www.ietf.org/rfc/rfc1868.txt
.IP 3.
RFC 2462 IPv6 Duplicate Address Detection
.br
http://www.ietf.org/rfc/rfc2462.txt
.IP 4.
RFC 3927 Dynamic Configuration of IPv4 Link-Local Addresses
.br
http://www.ietf.org/rfc/rfc3927.txt