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

Alexandru Petrescu <alexandru.petrescu@gmail.com> Wed, 25 September 2013 11:27 UTC

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Date: Wed, 25 Sep 2013 13:27:14 +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> <5241C0B6.9040200@gmail.com> <52428618.21ab440a.16d7.62d5@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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Hi Leaf,

I am not sure there exists a term 'DHCPv6 Requestor' as depicted below.

Also, the Relay Agent is separated from the Requesting Router by at most 
1-hop.  The Relay Agent and the RR must be Neighbors in terms of ND, I 
think.  But the figure shows one Access Network, which I dont know what 
you mean.  If you mean a point-to-point link (like PPP protocol) then I 
agree with it, because it is just 1-hop.  But if you mean a complex 
graphs of IP routers and many hops then I don't know whether it works.

But I agree with the figure overall, it is one potential deployment.

Alex

Le 25/09/2013 08:43, Leaf Yeh a écrit :
> I suppose the network scenario on this topic, i.e. routing issue associated
> with the DHCPv6-PD, is the same as that of
> ietf-dhc-dhcpv6-agentopt-delegate-04.
>
> Draft-ietf-dhc-dhcpv6-prefix-pool-opt-03 has 2 Network Architectures for the
> scenario discussion. One is as follows
>
>               +------+------+  DHCPv6 Server
>               |    DHCPv6   |  (e.g. Binding entry:
>               |    Server   |        Relay=nfi-GUA#2,
>               |             |        Interface-ID=cfi#3,
>               +------+------+        Prefix Pool=2001:db8:1200::/40)
>                      |
>             _________|_________
>            /                   \
>           |  ISP Core Network   |
>            \___________________/
>                      |
>                      |
>                      |  Network-facing interface
>                      |         (e.g. IPv6 address=nfi-GUA#2)
>               +------+------+
>               |   Provider  |
>               |     Edge    |  DHCPv6 Relay Agent, DHCPv6 Requestor
>               |    Router   |
>               +------+------+
>                      |  Customer-facing interface
>                      |         (e.g. Interface-ID=cfi#3)
>                      |               Prefix Pool=2001:db8:1200::/40)
>             _________|_________
>            /                   \
>           |   Access Network    |
>            \___________________/
>                      |
>                      |
>               +------+------+
>               |   Customer  |  DHCPv6 Client
>               |     Edge    |  DHCPv6-PD Requesting Router
>               |    Router   |  (e.g. customer network
>               +------+------+        =2001:db8:1234:5600:/56)
>                      |
>             _________|_________
>            /                   \
>           |  Customer Network   |
>            \___________________/
>
>
> Best Regards,
> Leaf
>
>
>
> -----Original Message-----
> From: Alexandru Petrescu [mailto:alexandru.petrescu@gmail.com]
> Sent: Wednesday, September 25, 2013 12:41 AM
> To: Leaf Yeh
> Cc: 'Ralph Droms'; dhcwg@ietf.org
> Subject: Re: discussion about PD-Relay-route
>
> 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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