Re: AW: Guidelines for Numbering IPv6 Point-to-Point Links and Easing the Addressing Plans

[Tim Chown <tjc@ecs.soton.ac.uk>]

Are there also possibily PIM issues?  Would using only link locals cause 
problems for PIM-SM where the Register messages are sent to the RP from 
a link-local interface on a CPE acting as the DR?  For example, with the
Register Stop messages?   We ran into this a while ago, but I can't 
remember the specifics right now :)

I agree with Fred; from a management point of view, the less explicit 
numbering required the better, as that implies the least renumbering at 
a later date...

Tim

On Wed, Mar 01, 2006 at 04:39:30PM -0500, Chip Popoviciu (cpopovic) wrote:
> 
> Along these lines there are two other aspects that are worth
> considering:
> 
> 1. A single address with scope larger than link-local would indeed be
> sufficient for a router as long as the network management policies and
> tools do not need to reach specific interfaces for troubleshooting
> purposes for example.
> 
> 2. In the case of a Service Provider that offers VPN services, an
> address with a scope larger than link-local is necessary for each VRF
> for things such as PMTU discovery. In that case, it might be easier to
> simply assign that address to the PE-CE link rather than create for
> example a loopback for each VRF. 
> 
> In principle link-locals are sufficient for the PE-CE link however in
> practice, all little details considered, people might end up assigning
> more than that to the link. And in that sense, it will be better to use
> a prefix set aside by the SP for its own infrastructure rather than what
> is delegated to the customer (as Ole mentioned).
> 
> Regards,
> Chip
> 
> -----Original Message-----
> From: owner-v6ops@ops.ietf.org [mailto:owner-v6ops@ops.ietf.org] On
> Behalf Of Fred Baker (fred)
> Sent: Wednesday, March 01, 2006 11:30 AM
> To: Bonness, Olaf
> Cc: Ole Troan (otroan); jordi.palet@consulintel.es; v6ops@ops.ietf.org
> Subject: Re: AW: Guidelines for Numbering IPv6 Point-to-Point Links and
> Easing the Addressing Plans
> 
> My assumption as a routing geek is that the only reasonable use of a
> numbered point to point link is to address an end station; it needs an
> address to be useful in the network. But any router/router point-
> to-point interface should be supportable using link-local addresses.  
> A router needs one address reachable by its administration (eg non-
> link-local), to be a member of any prefix on a LAN that it is serving,
> and to be able to reach p/p-connected end stations it serves.
> 
> On Mar 1, 2006, at 5:41 AM, Bonness, Olaf wrote:
> 
> >>
> >>    4.  Routing Aggregation of the Point-to-Point Links
> >>
> >>    Following this approach and assuming that a shorter prefix is
> >>    typically delegated to a customer, in general a /48 [4], it is
> >>    possible to simplify the routing aggregation of the point-to-point
> >>    links.  Towards this, the point-to-point link may be numbered 
> >> using
> >>    the first /64 of a given /48.
> >>
> >> using the first (or any) subnet of a larger prefix, breaks the 
> >> conceptual model of DHCP prefix delegation. the prefix is delegated 
> >> to the requesting router and cannot be used to number the link 
> >> between the delegating and requesting router.
> >
> > My assumption from a service provider point of view would be to use a 
> > dedicated sub-preaefix (e.g. /48)of my own aggregate to address the 
> > point-to-point links (e.g. /64)  to the custumers (in the case I have 
> > to do this).
> >
> > cu
> > 	Olaf
> 

-- 
Tim/::1