Lee,

> But there is no NAT hole punching is involved, why use l2tp instead of
> stateless IPv4-in-IPv6?

well, only because it is there, implemented and deployable.

I missed that 4over6 is stateless, I thought it was the equivalent of a 
configured IPv4 over IPv6 tunnel?

cheers,
Ole



> 
> /Yiu
> 
> On 3/31/11 3:29 AM, "Ole Troan" <[email protected]> wrote:
> 
>> Yiu,
>> 
>>>> reading drafts during the plenary post working group session.
>>>> 
>>>> 1) what does this solution offer that isn't in RFC5571? different
>>>> encapsulation?
>>> 
>>> Similar but there is a major difference. RFC5571 is 6over4 using l2tpv2
>>> to
>>> punch through the NAT. This doesn't need this requirement, so l2tpv2
>>> isn't
>>> needed. 
>> 
>> RFC5571 specifies both IPv4 over IPv6 and IPv6 over IPv4.
>> so the difference with this draft is that you rather want RFC2473
>> encapsulation rather than PPP/UDP?
>> 
>> the main argument for choosing L2TP in the first place, was that all the
>> infrastructure was available, including LNSes, LAC implementations and
>> backend AAA infrastructure.
>> 
>> doesn't this argument still hold for the hub and spoke case?
>> 
>> the main short-coming of the RFC5571 as I see it is the lack of
>> provisioning... if we fixed that would 5571 be more palatable as a
>> solution?
>> 
>>>> 2) host initiated. does this propose to support hosts behind a CPE? how
>>>> would they then be
>>>> provisioned?
>>> 
>>> The idea is the CPE will be the dhcp relay agent which will relay the
>>> dhcp
>>> requests from the hosts behind the CPE to the dhcp server. That said,
>>> there are details we need to sort out such as the CPE must be also
>>> provisioned an ipv4 address from the same subnet to support
>>> hair-pinning.
>>> Also the servers behind the CPE are normal servers, we need to detail
>>> how/when to create the binding in the NAT table so that it won't require
>>> the servers to send keepalive to the TC.
>> 
>> the Basic IPv6 CE draft (to be RFC6204) only suggest to pass across some
>> well known options from the WAN side DHCP client to the LAN side DHCP
>> server. perhaps you would suggest new text to the Advanced CE draft
>> suggesting that all unknown stateless DHCP option should be passed across?
>> 
>> cheers,
>> Ole
>> 
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> 

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