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

[Ray Hunter <[e-mail]>]

[e-mail] wrote:
> 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/
>
>
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