Re: [netext] #4: Logical interface support: Point to point links

Julien Laganier <julien.ietf@gmail.com> Tue, 15 March 2011 23:50 UTC

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References: <AANLkTin_ZbJmkbS3d2U0RGcSp4nCFD0H_VjeUQzQdB6H@mail.gmail.com> <C9A4171A.13628%sgundave@cisco.com>
Date: Tue, 15 Mar 2011 16:51:31 -0700
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From: Julien Laganier <julien.ietf@gmail.com>
To: Sri Gundavelli <sgundave@cisco.com>
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Cc: netext@ietf.org
Subject: Re: [netext] #4: Logical interface support: Point to point links
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Sri:

I am going to repeat it once again: you are equating advertizing or
per-MN subnet prefix to a point-to-point link, but these are two
different things, thus I am saying that we have a problem as 5213 is
limited to support of point-to-point links.

--julien

2011/3/14 Sri Gundavelli <sgundave@cisco.com>:
> Julien:
>
> Lets see, what is the violation here ?
>
> - We are stating the logical interface appears to the applications as an
> interface attached to a shared link. For the simple reason, that we have
> multiple neighbors on different network segments attached through different
> sub-interface of that logical interface. We don't have a single
> neighbor/MAG.
>
> - "Underneath the logical interface ...", there are sub-interfaces which may
> be very well attached to different p2p links. As long as the network has the
> semantics to send a RA with PIO, exclusively to this node, no other node on
> that access link can receive that Prefix set, we are confirming to 5213 link
> model. From any of the MAG's perspective, attached to any of the access
> links, it can still be kept as a p2p link
>
> - Exposing the logical interface as a shared link to the applications on the
> *mobile node*, is not violating 5213 principles. The path chosen for a
> packet through a sub-interface can be still a p2p link and the rules of
> link-layer resolution of the peer, or adding l2 headers skipping l2
> resolution, is still the approach in use.
>
>
>
>
> Sri
>
>
>
>
>
>
>
>
> On 3/14/11 5:20 PM, "Julien Laganier" <julien.ietf@gmail.com> wrote:
>
>> Sri -
>>
>> 5213 supports only PtP links thus I do not understand how the
>> following resolution resolves anything. Please clarify what is the
>> issue you' re addressing and how this is addressing it.
>>
>> --julien
>>
>> On Mon, Mar 14, 2011 at 4:24 PM, Sri Gundavelli <sgundave@cisco.com> wrote:
>>>> #4: Logical interface support: Point to point links
>>>
>>>  Clarify the use and
>>>> behavior of the logical interface on PtP links.
>>>
>>>
>>> Folks: Again, reflecting the team's contributions on this topic, the authors
>>> of this document have discussed this and resolve it with the following text.
>>> The key points we tried to reflect are around that the logical interface
>>> appears to the application as a shared link. There were thoughts around
>>> making it appear like a p2p link, given that there are multiple neighbors on
>>> each sub interface, this choice appears reasonable. With respect to how a
>>> packet is transmitted, is still based on the chosen link model at each sub
>>> interface level. Let us know, if you see any issues with it. This is proven
>>> based on the multiple implementations from some of the co-authors of this
>>> doc.
>>>
>>>
>>>
>>>
>>> ---
>>> 6.3.  Supported Link models for a logical interface
>>>
>>>  The sub-interfaces of a logical interface can be bound to a point-to-
>>>   point or a shared link (Example: LTE and WLAN).  The logical
>>>   interface appears as a shared-link to the applications, and adapts to
>>>   the link model of the sub-interface for packet communication.  For
>>>   example, when transmitting a packet on a sub-interface which is
>>>   attached to a p2p link, the transmission conforms to the p2p link
>>>   model and when transmitting on a sub-interface attached to a shared
>>>   link, the transmission conforms to the shared link model.
>>>
>>>   Based on the link to which the sub-interface is attached to, the
>>>   layer-2 resolutions may or may not be needed.  If the interface is
>>>   bound to a P2P link with PPP running, there will not be any link-
>>>   layer resolutions in the form of ARP/ND messages.  However, if the
>>>   interface is bound to a shared link such as Ethernet, there will be
>>>   ND resolutions.  The logical interface implementation has to maintain
>>>   the required link model and the associated state for each sub-
>>>   interface.
>>> --
>>>
>>>
>>>
>>>
>>> On 3/3/11 9:17 AM, "netext issue tracker" <trac+netext@trac.tools.ietf.org>
>>> wrote:
>>>
>>>> #4: Logical interface support: Point to point links
>>>
>>>  Clarify the use and
>>>> behavior of the logical interface on PtP links.
>>>
>>> --
>>>>
>>> ---------------------------------------+------------------------------------
>>>
>>>> Reporter:  basavaraj.patil@Š          |       Owner:  telemaco.melia@Š
>>>>
>>>     Type:  defect                     |      Status:  new
>>>>
>>>  Priority:  major                      |   Milestone:
>>>>
>>> Component:  logical-interface-support  |     Version:
>>>>
>>>  Severity:  -                          |    Keywords:
>>>>
>>> ---------------------------------------+------------------------------------
>>>
>>>>
>>> Ticket URL: <http://trac.tools.ietf.org/wg/netext/trac/ticket/4>
>>> netext
>>>> <http://tools.ietf.org/netext/>
>>>
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>
>