Re: ping-pong phenomenon with p2p links & /127 prefixes

[Mark Smith <ipng@69706e6720323030352d30312d31340a.nosense.org>]

On Mon, 23 Aug 2010 17:23:09 -0400
Jared Mauch <jared@puck.nether.net> wrote:

> 
> On Aug 23, 2010, at 4:49 PM, Mark Smith wrote:
> 
> > On Mon, 23 Aug 2010 09:55:48 -0400
> > Jared Mauch <jared@puck.nether.net> wrote:
> > 
> >> 
> >> On Aug 23, 2010, at 9:17 AM, Mark Smith wrote:
> >> 
> >>> On Mon, 23 Aug 2010 14:11:04 +0200 (CEST)
> >>> sthaug@nethelp.no wrote:
> >>> 
> >>>>> These mechanisms are applicable to any type of link, would preserve the
> >>>>> simplicity of universal 64 bit IIDs and the other benefits of them e.g.
> >>>>> CGAs, as well as avoiding the ping-pong problem.
> >>>> 
> >>>> IMHO, the "universality" of 64 bit IIDs went down the drain the moment
> >>>> router vendors allowed longer than 64 bit netmasks to be configured.
> >>>> 
> >>> 
> >>> So how does that prevent those prefix lengths being changed to /64?
> >> 
> >> Because you would then end up with overlapping address space that is unreachable in a production deployment.
> >> 
> > 
> > Not necessarily. If I were to deploy /127s, I'd be allocating /64s to
> > the links.
> 
> You may put a /64 on your /127 links in addition, but most people only put
> one IP subnet on a link, otherwise they might want redirects ;)
> 

I meant reserving a /64 for the link and then configuring a /127 prefix
length on it. If my concerns about /64s were resolved, all I'd need to
do would be change the prefix length back to a /64.

> >> But that would be an operational item and not an standards body item?
> >> 
> > 
> > This has been cross posted to v6ops.
> 
> Operationally the vendors may be violating some RFC, so lets publish what is
> relevant and working today so we can all move on?  We can deal with
> any additional updates and items with "how IPv6" works elsewhere or in a
> new document so we can move /127 on p2p links along?
> 

So that leaves the problem still existing on network edge LANs and
virtual P2P links between customer aggregation routers and CPE, of
which there'l be millions. Maybe you, Steinar and Randy don't
have to worry about those types of links, but others of us do.

A complete solution would solve the problem for all link types, not
just mitigate it for point-to-point links in the backbone.

Regards,
Mark.