Subject: Re: ISP IPv6 Deployment Scenarios in Broadband Access

From: Pekka Savola <[email-masked]>
Date: Fri, 5 Nov 2004 08:42:14 +0200 (EET)

Hi,

There's one thing that came across when doing the operator poll on v6 
deployment which might warrant more discussion in the document...

On Thu, 21 Oct 2004, Ciprian Popoviciu wrote:
> We integrated the feedback received on the first version of the "ISP IPv6 
> Deployment Scenarios in Broadband Access" draft and posted the updated 
> document. You can also find it at:
>
> [...]draft-asadullah-v6ops-bb-deployment-scenarios-01.txt
>
> We would like to thank Brian Carpenter, Patrick Grossetete, Benoit Lourdelet, 
> Tschofenig Hannes, Gert Doering,  Alexander Koch for their feedback and 
> particularly Pekka for all his help along with his feedback.

An operator which has deployed bridged-mode DSL ('RBE') said that the 
only solution for providing bulk v6 access at the moment is requiring 
the use of DHCPv6 for address assignment (i.e.: because DHCPv4 is 
snooped for v4, the vendors seem to have implemented the same kind of 
snooping for v6 w/ DHCPv6).

Needless to say that that sounds like a very big problem.  Requiring 
DHCPv6 for address assignment for something like this seems ludicurous 
at least :-).

Alternatives seem to be:
  1) defining each /64 prefix to advertise for each customer manually, 
not using bulk methods: this does not scale, so it's not an option.
  2) checking whether providing a single, shared /64 for all the 
customers would work (what if there are address conflicts?  what about 
communication inside the prefix?  does this work?)
  3) implementing a mechanism which would allow for direct mapping of 
VLAN or VC information to the advertised v6 prefix.  For example, so 
that for VLAN=100 you could just configure a bulk command 
'map-vlan-to-v6-prefix 2001:db8:1::/48', and it would hand out e.g. 
'2001:db8:1:64::/64' to the customer -- or something like that, 
allowing bulk configuration
  4) putting all the customers' v6 prefix information in a RADIUS or 
similar database, so that the advertisement information could be 
digged up from there.  A lot of work, and does not work automatically. 
This would also need some glue between bulk config and RADIUS.

All of this except 2) seems to be in the realm of implementations, not 
requiring IETF protocol modifications, but to get these features 
discussed and on the table, maybe such requirements and possible 
solutions should be described in the document.

Could someone check whether 2) is possible or not, and if yes, which 
kind of support it requires in the equipment ?

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

---

From: Gert Doering <[email-masked]>
Date: Thu, 18 Nov 2004 15:36:31 +0100

Hi,

> snooping for v6 w/ DHCPv6).
[..]
> This would also need some glue between bulk config and RADIUS.

How are people envisioning "bulk access with IPv6" anyway?

I'm wondering specifically about the nature of the IPv6 allocations 
- are "operators" planning to do dynamic IPv6 allocations (today you get
a dynamic IPv4 /32, in the future you get a dynamic IPv6 /64)?  

Or are people planning to assign static /48s?

We do the latter, so we need to couple RADIUS and IP(v4/v6) address
management anyway - no big difference here for IPv6 access.  

OTOH, we have no "bulk access with RBE" anyway.   Bulk DSL is done with 
PPPoE/L2TP, which works fine (on Cisco) with IPv6 address pools for
assignment, or static assignments coming from radius.

Gert Doering
        -- NetMaster
-- 
Total number of prefixes smaller than registry allocations:  66629  (65398)

SpaceNet AG                 Mail: [email-masked]
Joseph-Dollinger-Bogen 14   Tel : +49-89-32356-0
80807 Muenchen              Fax : +49-89-32356-299

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From: Ciprian Popoviciu <[email-masked]>
Date: Fri, 19 Nov 2004 14:30:04 -0500

Hello Gert,

Please see comments/answers in line ...

>How are people envisioning "bulk access with IPv6" anyway?

Do you mean wholesale model where the NAP doesn't handle addressing?

>Or are people planning to assign static /48s?

In these broadband deployments there is an IPv6 prefix on the 
link/virtual-link to each customer. The address allocation in some of these 
deployments is done in two ways:
1) The /64 is assigned to the link/virtual-link between the access router 
and the customer. The customer then uses autoconfig for its hosts that are 
all on the same network.
2) There is a /64 assigned to the link/virtual-link between the access 
router and the customer but DHCP-PD is used to provide the Customer 
Premises Router with a /48 that it is then used to automatically configure 
all the interfaces of that customer router with /64s. The hosts behind the 
customer router use autoconfig.

>assignment, or static assignments coming from radius.

True, with RBE the NAP becomes responsible of address management etc and 
that is different then the typical wholesale model however, people are will 
to change that in exchange of benefits that they get from IP control close 
to the end customer (the multicast service We talk about in our draft). The 
NAP doesn't have to become an ISP for this.

Of course, the PPPoE/L2TP option discussed in the draft is also available 
if one wants to maintain the v4 deployment models.

Thank you!
Chip

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From: Gert Doering <[email-masked]>
Date: Tue, 23 Nov 2004 09:39:16 +0100

Hi,

> Do you mean wholesale model where the NAP doesn't handle addressing?

Actually, the question "will the NAP handle addressing" is part of the
question - it's the distinction between "users get statically assigned
IPv6 networks" and "users get dynamically assigned /64s" (or similar).

[..]
> customer router use autoconfig.

Ummm, well.  This is the technical answer (which is important to see
written down), but fails to answer the thing that I'm mostly curious
about - dynamic vs. static assignments.

I assume that you're working with Cisco customers that do some initial
IPv6 broadband deployments, so maybe you can explain how those are 
currently doing the address distribution (or what the plans are)?

[..]
> NAP doesn't have to become an ISP for this.

Good point.  This would certainly change the way bulk DSL access is done 
over here "as of today".

thanks,

Gert Doering
        -- NetMaster

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From: Ciprian Popoviciu <[email-masked]>
Date: Tue, 23 Nov 2004 23:19:02 -0500

Hi Gert,

>IPv6 networks" and "users get dynamically assigned /64s" (or similar).

All deployments that I have seen rolled out or being planned assigned the 
same prefix to a given customer every time it is coming on line.

>currently doing the address distribution (or what the plans are)?

The two options listed above are used in operational deployments. In the 
first case it is clear that the address is statically assigned. In the 
second case it should be mentioned that typically, the same prefix is 
assigned via DHCP-PD to the user every time it comes on line.

Regards,
Chip