Re: [dhcwg] discussion about PD-Relay-route

Alexandru Petrescu <alexandru.petrescu@gmail.com> Tue, 24 September 2013 16:41 UTC

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Date: Tue, 24 Sep 2013 18:41:26 +0200
From: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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To: Leaf Yeh <leaf.yeh.sdo@gmail.com>
References: <489D13FBFA9B3E41812EA89F188F018E18654EE6@xmb-rcd-x04.cisco.com> <5212694A.6000807@gmail.com> <CAOv0Pi87akb24PaYJKPzK3+cfCr1DHDu-h2sF3HwTxBvzZC9+w@mail.gmail.com> <C2A9B74C-A52C-4605-824E-40E3E9C190E0@gmail.com> <52305986.2010503@gmail.com>, <FB56FE0A-9088-4040-BCE7-C69399D64171@employees.org> <ECD231FD-8D3F-4067-8BDE-AE567D96F6A7@cisco.com> <52306010.4090001@gmail.com> <5E91E9B8-6E22-46DD-A687-B4983BD0B508@gmail.com> <523f2fa3.c9ed440a.55a9.ffffc38e@mx.google.com> <52402AF3.8010407@gmail.com> <5240486E.20501@gmail.com> <52405701.9070506@gmail.com> <2CC893E4-7C48-4345-A40E-E2B3822C14ED@gmail.com> <5241951B.2070606@gmail.com> <5241b722.c467440a.7dd8.ffff8e3c@mx.google.com>
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Cc: dhcwg@ietf.org, 'Ralph Droms' <rdroms.ietf@gmail.com>
Subject: Re: [dhcwg] discussion about PD-Relay-route
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Le 24/09/2013 18:00, Leaf Yeh a écrit :
> Ralph > And how does that route get to the other routers?
>
> Alexandru > They are all on the same link, and one mechanism used to
> install routes dynamically is during ICMP Redirect.
>
> Are you talking about the following network structure?

In that figure, Router-A has an additional link towards the Internet. 
And Router-B runs the Relay software, and has only one link - as pictured.

There is no term 'Delegated Router' (sorry no offence :-).  There is a 
'Delegating Router' and that should be the DHCPServer situated deep in 
the infrastructure (please draw it).

Also, the 'CE Router/RR' has an additional link to other Hosts which use 
the delegated prefix to configure addresses for selves.  It's the local 
LAN, of which that RR is in charge of.

In that case - yes, I think such a figure is good for some deployments 
for reasons I could describe.

Yours,

Alex

>
> mailbox:///C:/data/imap-cea-start7sept2011/ietf.sbd/ietf-dhcwg?number=56814925&header=quotebody&part=1.2&filename=image001.png
>
> Only Router-A acts as the DR.
>
> Is this structure important in your mind?
>
> Best Regards,
>
> Leaf
>
> -----Original Message-----
> From: dhcwg-bounces@ietf.org <mailto:dhcwg-bounces@ietf.org>
> [mailto:dhcwg-bounces@ietf.org] On Behalf Of Alexandru Petrescu
> Sent: Tuesday, September 24, 2013 9:35 PM
> To: Ralph Droms
> Cc: dhcwg@ietf.org <mailto:dhcwg@ietf.org> WG
> Subject: Re: [dhcwg] Advancing RFC 3315 and RFC 3633 to Internet Standard
>
> Le 24/09/2013 10:32, Ralph Droms a écrit :
>
>>
>
>> On Sep 23, 2013, at 3:58 PM 9/23/13, Alexandru Petrescu
>
>> <alexandru.petrescu@gmail.com <mailto:alexandru.petrescu@gmail.com>> wrote:
>
>>
>
>>> Le 23/09/2013 15:55, Tomek Mrugalski aécrit :
>
>>>> On 23.09.2013 13:50, Alexandru Petrescu wrote:
>
>>>>> Le 22/09/2013 19:57, Leaf Yeh aécrit :
>
>>>>>> Ralph > The piece of network equipment that implements the relay
>
>>>>>> agent routes, and that network equipment *might* also need a
>
>>>>>> route.
>
>>>>>>
>
>>>>>> On the PE router implementing relay for DHCPv6-PD, it always needs
>
>>>>>> add the associated route for the CE's network of delegated prefix.
>
>>>>>> I can't see *might* here.
>
>>>>>
>
>>>>> I agree with the doubt.  I don't see a might, but rather a must.
>
>>>>> Otherwise it doesn't work.
>
>>>>>
>
>>>>> But maybe I dont understand the word 'might' as a native speaker
>
>>>>> could hear it.
>
>>>> Relay agent is functionality that can be provided by a piece of
>
>>>> software. You can run it on any box that is connected to more than
>
>>>> one network. Although typically such a box serves as a router, it
>
>>>> doesn't have to.
>
>>>
>
>>> You mean a Relay agent which runs on a pure Host (single real
>
>>> interface, no additional virtual/real interfaces)?
>
>>>
>
>>> Even in that case it (or the Router on the same link which is
>
>>> connected to the Internet) will need to install a route towards the
>
>>> Requesting Router's interface for the delegated prefix.
>
>>
>
>> And there's the exact point of the discussion - if the relay agent is
>
>> not implemented on the router that needs the route, passing the route
>
>> in the DHCPv6 message exchange through the relay agent won't get the
>
>> route to the appropriate router.
>
>>
>
>>>
>
>>> In all cases, the Relay and other routers on that link MUST install a
>
>>> route.
>
>>
>
>> And how does that route get to the other routers?
>
> They are all on the same link, and one mechanism used to install routes
> dynamically is during ICMP Redirect.
>
>>> Whether they do it at allocation time, at ICMP Redirect time, or at
>
>>> manual config time - is another matter.
>
>>
>
>> I'm not saying the route installation can't be accomplished through
>
>> DHCPv6.  I think you'll need to address the specific issues I raised
>
>> in previous e-mail to publish a specification for passing routing
>
>> information to the appropriate router through a DHCPv6 message
>
>> exchange with a host.
>
> Ok, my point is whether or not we could formulate a problem statement
> for this: there is a need for a route in the concerned routers, after
> the PD operation.  Without that route the communication can't be
> established between Hosts configured with an address prefixed by the
> delegated prefix.
>
> Alex
>
>>
>
>> - Ralph
>
>>
>
>>>
>
>>> Without that route the whole schmillblick doesn't work.
>
>>>
>
>>> Alex
>
>>>
>
>>>
>
>>> _______________________________________________ dhcwg mailing list
>
>>>dhcwg@ietf.org <mailto:dhcwg@ietf.org>
> https://www.ietf.org/mailman/listinfo/dhcwg
>
>>
>
>>
>
>>
>
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