Re: Comments on IPv6 Prefix Subdelegation

> From: Fred Baker <fred@cisco.com>
> Date: Thu, 30 Jul 2009 01:53:30 -0400
> To: "Stark, Barbara" <bs7652@att.com>
> Cc: <draft-ietf-v6ops-ipv6-cpe-router@tools.ietf.org>,
> <draft-donley-ipv6-cpe-rtr-use-cases-and-reqs@tools.ietf.org>, IETF IPv6
> Mailing List <ipv6@ietf.org>
> Subject: Re: Comments on IPv6 Prefix Subdelegation
> 
> 
> 
> On Jul 29, 2009, at 11:03 PM, Stark, Barbara wrote:
>> Why does it need to be a dynamic routing protocol? Why not a simple
>> configuration protocol, like with RFC 4191 or a DHCPv6 option as
>> suggested in
>> http://tools.ietf.org/html/draft-dec-dhcpv6-route-option-01?
> 
>> Why do the peered routers (such as CPE RTR 1 and 2, in Fig 3) need to
>> know which routes other routers claim to serve?
> 
> Um, what does a router do? Look at the example in the text and ask
> yourself if you want an average user (my canonical "average user"
> being my daughter, who wanted me to come to her house to install a
> camera on her computer so she could use it on Skype - "did you try
> plugging it in?") manually installing routes in each of the four
> routers when they could in fact learn them from each other directly?
[jjmb] Agree here the notion of the user having to configure the network
manually is not going to fly.
> 
>> There shouldn't be misdirected traffic, if the routes are known to
>> downstream devices.
> 
> Not so. First, communications are not limited to accesses to systems
> outside the SOHO - music, for example, is often an access to a server
> in the home. Second, the fact that a datagram was delivered to a
> device in the home via one CPE is no guarantee that its response will
> use the same CPE.
> 
>> Or
>> is it the home/office RTRs (Fig 3) who need to know which prefixes
>> have
>> been assigned to each other, advertising on their WAN interfaces? It
>> seems like if the home/office RTRs don't know about each other, it
>> doesn't really hurt efficiency that much; it'll still work. They'll
>> send
>> the messages up to the next hop (CPE RTR) serving that prefix, and
>> then
>> it'll get routed down to the right home/office RTR.
>> 
>> If peered CPE RTRs do need to know each others' routes, why can't they
>> get it through an RFC 4191 or DHCPv6 method (this would be on the LAN
>> interface). I realize that there are those who say it's wrong for them
>> to solicit (RS or DHCPv6) on their LAN interfaces -- but why is it
>> wrong?
> 
> ... This comes back to my question about manual configuration. If I
> can make it work easily, what is the argument for not doing so?
[jjmb] there should not be an argument, alleviating manual configuration
where possible is the right thing.  This would not preclude more advanced
users from manually configuring whatever they like.
> 
>> And don't these routes need to get propagated down to the hosts,
>> because
>> hosts may individually have multiple interfaces (e.g., smartphone with
>> Wi-Fi and 3G)?
> 
> That gets into a much larger discussion. Willing to go there, but
> that's beyond this draft.
> 
>> Barbara
>> 
>>> -----Original Message-----
>>> From: ipv6-bounces@ietf.org [mailto:ipv6-bounces@ietf.org] On Behalf
>> Of
>>> Fred Baker
>>> Sent: Wednesday, July 29, 2009 6:05 AM
>>> To: Azinger, Marla
>>> Cc: draft-ietf-v6ops-ipv6-cpe-router@tools.ietf.org;
>> draft-donley-ipv6-
>>> cpe-rtr-use-cases-and-reqs@tools.ietf.org; IETF IPv6 Mailing List
>>> Subject: Re: Comments on IPv6 Prefix Subdelegation
>>> 
>>> 
>>> On Jul 29, 2009, at 10:35 AM, Azinger, Marla wrote:
>>> 
>>>> Routing in such an environment calls for a routing protocol. Each
>>>> CPE must run either RIPv6 [RFC2080], IS-IS [RFC5308], or OSPF
>>>> [RFC5340] on a default route and to the homes interal upstream a
>>>> static default route. The issues raised in [RFC3704] also apply,
>>>> meaning that the two CPE routers may each need to observe the source
>>>> addresses in datagrams  they handle to divert them to the other CPE
>>>> to handle upstream
>>> 
>>> I'll figure something out there. This makes it sound like only the
>>> CPE
>>> routers have to run a routing protocol; in fact, all of the routers
>>> in
>>> the home have to run a routing protocol. But yes, something like
>>> that.
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