Subject: I-D Action: draft-ietf-6man-resilient-rs-04.txt

From: [email-masked]
Date: Tue, 14 Oct 2014 19:50:22 -0700

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           : Packet loss resiliency for Router Solicitations
        Authors         : Suresh Krishnan
                          Dmitry Anipko
                          Dave Thaler
	Filename        : draft-ietf-6man-resilient-rs-04.txt
	Pages           : 6
	Date            : 2014-10-14

Abstract:
   When an interface on a host is initialized, the host transmits Router
   Solicitations in order to minimize the amount of time it needs to
   wait until the next unsolicited multicast Router Advertisement is
   received.  In certain scenarios, these router solicitations
   transmitted by the host might be lost.  This document specifies a
   mechanism for hosts to cope with the loss of the initial Router
   Solicitations.  Furthermore, on some links, unsolicited multicast
   Router Advertisements are never sent and the mechanism in this
   document is intended to work even in such scenarios.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-6man-resilient-rs/

There's also a htmlized version available at:
http://tools.ietf.org/html/draft-ietf-6man-resilient-rs-04

A diff from the previous version is available at:
http://www.ietf.org/rfcdiff?url2=draft-ietf-6man-resilient-rs-04

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Ray Hunter <[email-masked]>
Date: Sat, 25 Oct 2014 16:04:51 +0200

> ftp://ftp.ietf.org/internet-drafts/
I'm unsure of the exact status of this document as I can't recall 
reading it before, and it has been substantially revised in the last diff.

Whilst I recognise that some early packet loss may result in a delay in 
discovering a default router on a network, I remain to be convinced that 
this draft is not harmful in its current form.

Resistance to DHCP(v6) drafts often cite infinite solicitations as being 
a "bad thing", and this draft is effectively repeating the same 
behaviour for links where either no IPv6 has been configured, or for 
situations where no IPv6 router providing a default route is two-way 
reachable.

An upper cap on how long these additional RS retransmissions should be 
repeated is therefore advisable IMHO e.g. 3 * the maximum time between 
unsolicited multicast Router Advertisements (MaxRtrAdvInterval) (or 
absolute max of 5400 seconds).

This is different to DHCPv6, where there is no possibility for DHCPv6 
servers to send unsolicited multicast announcements of the ADVERTISE 
state AFAIK.

-- 
Regards,
RayH

---

From: Suresh Krishnan <[email-masked]>
Date: Mon, 27 Oct 2014 02:54:59 +0000

Hi Ray,
   Thanks for your comments. Please find responses inline.

> reading it before, and it has been substantially revised in the last diff.

The diff is based on the results of the WGLC.

http://www.ietf.org/mail-archive/web/ipv6/current/msg21227.html

> situations where no IPv6 router providing a default route is two-way

Yes. This has been discussed in the WG before and Section 4 of the draft 
has been essentially unchanged since adoption two years ago. The rate 
limiting was put in place to ensure that the load on such networks is 
not excessive.

> absolute max of 5400 seconds).

One of the issues we are trying to address is the case where LAN 
connectivity for a host is established before WAN connectivity as 
described in the introduction. Setting a hard upper bound will not help. 
Also the rate limiting will limit the RSs to approximately 1RS/hr/host.

Thanks
Suresh