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

[Suresh Krishnan <[e-mail]>]

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

On 10/25/2014 10:05 AM, Ray Hunter wrote:
>
>
> [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.

The diff is based on the results of the WGLC.

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


>
> 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.

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.

>
> 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).

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