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

["Chip Popoviciu \(cpopovic\)" <cpopovic@cisco.com>]

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