I-D Action: draft-ietf-6man-enhanced-dad-01.txt

[Ray Hunter <[e-mail]>]

I have read this draft, and think this work is important.

Some dumb questions for your consideration:

Since the (tentative) IID and DAD operation is address and interface 
specific; as well as the nonce, should the node also remember on which 
interface the NS(DAD) was sent, and also for which (tentative) address?

Should the node generate a separate nonce per instance of the DAD 
algorithm, or per interface initialisation?
[DAD may be performed multiple times for initialising a single 
interface, and these may run in parallel if there are multiple prefixes 
per interface, or if temporary addresses are in use as well as SLAAC and 
DHCPv6...]

Section 4.3 says "an interface on the node"

What should a receiver do if a node receives its own NS(DAD) on another 
interface other than the source interface which is performing DAD?
[use case: two L3 interfaces on one node connected to one common L2 
link, where one interface re-initialises or wants to use a new temporary 
address and thus performs DAD. That isn't a loopback condition or error 
condition at all if that NS(DAD) packet is received on the other interface.]

I think the text in section 4.3 could do with some clarification on 
sending and receiving interfaces.

There are high availability situations that intentionally cause 
collisions of IID and a virtual IPv6 address [e.g. HSRP IPv6].
Do these need to be explicitly excluded from this draft? Or is that 
someone else's problem?
[There is a table on the relevant manufacturers website labelled Table 
19 "HSRP and IPv6 ND Addresses " which shows when the virtual MAC/ 
Virtual IPv6 is used for messages. AFAIK DAD is never performed on the 
virtual address, as prevention of duplicate addresses is handled in the 
HSRP protocol itself]

There are high availability cases where multiple NICs are connected in 
parallel [Teaming].
Does this require any special treatment? Or simply a clarification that 
DAD is performed on the resulting virtual NIC interface or LACP bundle 
rather, than individual physical links? Or is this plain obvious?

When is it safe for a node to garbage collect the stored nonce?
When should a node garbage collect the stored nonce [e.g. to  cover 
equipment moves and interface re-patching]?
Once DAD completes?

Regards,
RayH

> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>   This draft is a work item of the IPv6 Maintenance Working Group of the IETF.
>
> 	Title           : Enhanced Duplicate Address Detection
> 	Author(s)       : Rajiv Asati
>                            Hemant Singh
>                            Wes Beebee
>                            Eli Dart
>                            Wes George
>                            Carlos Pignataro
> 	Filename        : draft-ietf-6man-enhanced-dad-01.txt
> 	Pages           : 11
> 	Date            :2012-09-06
>
> Abstract:
>     Appendix A of the IPv6 Duplicate Address Detection (DAD) document in
>     RFC 4862 discusses Loopback Suppression and DAD.  However, RFC 4862
>     does not settle on one specific automated means to detect loopback of
>     Neighbor Discovery (ND of RFC 4861) messages used by DAD.  Several
>     service provider communities have expressed a need for automated
>     detection of looped backed ND messages used by DAD.  This document
>     includes mitigation techniques and then outlines the Enhanced DAD
>     algorithm to automate detection of looped back IPv6 ND messages used
>     by DAD.  For network loopback tests, the Enhanced DAD algorithm
>     allows IPv6 to self-heal after a loopback is placed and removed.
>     Further, for certain access networks the document automates resolving
>     a specific duplicate address conflict.
>
>
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-ietf-6man-enhanced-dad
>
> There's also a htmlized version available at:
> http://tools.ietf.org/html/draft-ietf-6man-enhanced-dad-01
>
> A diff from the previous version is available at:
> http://www.ietf.org/rfcdiff?url2=draft-ietf-6man-enhanced-dad-01
>
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/