Re: [lisp] Fwd: New Version Notification for draft-rodrigueznatal-lisp-oam-00.txt

Hi Matthieu and Stefano,

Thank you very much for reviewing the draft. Your comments are deeply
appreciated.

Please see inline.

On Mon, Aug 11, 2014 at 5:50 PM, Matthieu Coudron <matthieu.coudron@lip6.fr>
wrote:

> Dear all,
>
> we reviewed the draft and following offline discussions with Albert, you
> will find below a few comments.
>
> Best regards,
> Matthieu Coudron
> Stefano Secci
>
> ____________________________
> 2. Underlay definition
> "The underlay corresponds to the RLOC space"
> This appears as too restrictive, as information about the underlay could
> come also from local AS/domain-level information such as traffic
> engineering databases, monitoring tools, etc, unaware of LISP.
>
> [AR] I think we could reword that. How about this text?

"In most cases the underlay is equivalent to the RLOC space, however it can
also comprise information from external sources such traffic engineering
databases, monitoring tools, etc"

> ____________________________
> 3.2 MPTCP
> "Each of these sub-flows behaves as a legacy TCP flow and hence, from the
> network point of view, each sub-flow is a different TCP session. The
> network conditions over the different paths the sub-flows follow affect the
> whole MPTCP session.  Since MPTCP has to keep the aggregate session
> consistent, each aggregated flow can perform as good as the worst of the
> sub flows it integrates."
>
> This paragraph seems incorrect. MPTCP RFC 6182 section 2.1 states that
> MPTCP should be at least as good as TCP, which in practice is true except
> in a few cases (e.g., if a subflow with a large share of the window becomes
> inactive, then you need to wait several timeouts before being able to be
> aggressive enough on other subflows). The RFC does not precisely address
> the scheduling mechanisms, but if for instance you consider the Linux
> implementation (http://www.multipath-tcp.org), it sends a maximum amount
> of data on the subflow with the lowest RTT and once its window is full, it
> will send on the 2nd lowest RTT subflow etc... so providing there is enough
> buffering at each endpoint, in terms of sheer throughput MPTCP should be
> able to aggregate all the subflows independently of their latency. It is
> true though that if packets are not scheduled carefully on each subflow,
> then application latency may  increase.
>
>
[AR] I believe that we are on the same page here. The point that we tried
to make here is that "on worst case scenario, MPTCP performs as good as
TCP". Perhaps that was not stated clearly enough. Maybe we could keep this
paragraph short (one sentence) and just point people to MPTCP RFC. Would
that make sense?

> At LIP6, we already run LISP+MPTCP coupling experimentations (LISP
> providing topology informations and forwarding capabilities to the MPTCP
> layer), we documented last year in this article “Cross-layer Cooperation to
> Boost Multipath TCP Performance in Cloud Networks” available at:
> http://www-phare.lip6.fr/~secci/papers/CoSePuRaGa-CLOUDNET13.pdf . In our
> experiment, RTTs of the different paths were close to each other, which
> lead to very good performance, as the lower the RTT gap the better MPTCP
> performance.  See here another interesting article about this matter: "How
> hard can it be? Designing and Implementing a Deployable MPTCP" available at
> https://www.usenix.org/system/files/conference/nsdi12/nsdi12-final125.pdf
>

[AR] Thank you very much for the pointers, they provide good insight for
this draft. They are greatly appreciated :)

>
> ____________________________
> 4. Requirements / Device Discovery
> "This is solved for xTRs by sending Map Register messages."
>
> Did you mean Map Requests? Or can you explain why only Map Register?
>
> [AR] We were talking here about the fact that in vanilla LISP the
MappingSystem can be aware of existing xTRs since they keep sending
MapRegisters. The MapRegister process works already as an automated
discovery mechanism. We'll extend the sentence to clarify this.

>
> ____________________________
> 4. Requirements / Forwarding Actions
>
> "These actions can be implemented as extensions to the current
> specifications of LISP-TE or LISP-SR or be defined by means of a new LCAF."
>
> Here it would be better not to exclude existing LCAF. For the MPTCP
> use-case, we have a prototype using already proposed LCAF messages.
>

[AR] Good point. How about this?

"These actions can be implemented as extensions to the current
specifications of LISP-TE or LISP-SR, leverage on reusing existing LCAF
types or be defined by means of a new LCAF."

>
> ____________________________
> 7. Security Considerations
> "When including capabilities to allow for the discovery of devices and its
> capabilities, as well as the collection of metrics regarding the underlay
> and the local device itself, it should be taken into consideration that
> proper controls are put in  place to enforce strict policies as to which
> devices can access what type(s) of information."
>
> Do you have any protocol in mind to get metrics from the overlay to the
> underlay?
>

[AR] We're currently discussing this. Nothing fixed yet ;)

> Relevant nodes should be chosen carefully so that they are not malicious
> or misfunctioning. For instance the TCP RTT seen by a VM is higher than one
> seen by a physical machine due to the hypervisor scheduling latency.

[AR] That's indeed correct. We'll try to keep that in mind.

Thanks again for your comments. We hope you can keep contributing to this
draft :)

Best,
Alberto

>
>
>
>
> On 11/08/2014 16:46, Matthieu Coudron wrote:
>
>> ---------- Forwarded message ----------
>> From: Alberto Rodriguez-Natal <arnatal@ac.upc.edu>
>> Date: 2014-07-04 15:16 GMT+02:00
>> Subject: [lisp] Fwd: New Version Notification for
>> draft-rodrigueznatal-lisp-oam-00.txt
>> To: "lisp@ietf.org list" <lisp@ietf.org>
>>
>>
>> Dear all,
>>
>> We have just submitted a new draft discussing OAM (Operations
>> Administration Management) use-cases and requirements for LISP.
>>
>> Please, feel free to review it and provide feedback.
>>
>> Thanks,
>> Alberto
>>
>> ---------- Forwarded message ----------
>> From: <internet-drafts@ietf.org>
>> Date: Fri, Jul 4, 2014 at 10:01 PM
>> Subject: New Version Notification for draft-rodrigueznatal-lisp-oam-
>> 00.txt
>> To: Albert Cabellos-Aparicio <acabello@ac.upc.edu>, Marc
>> Portoles-Comeras <mportole@cisco.com>, Alberto Rodriguez-Natal
>> <arnatal@ac.upc.edu>, Michael Kowal <mikowal@cisco.com>, Darrel Lewis
>> <darlewis@cisco.com>, Fabio Maino <fmaino@cisco.com>
>>
>>
>>
>> A new version of I-D, draft-rodrigueznatal-lisp-oam-00.txt
>> has been successfully submitted by Alberto Rodriguez-Natal and posted to
>> the
>> IETF repository.
>>
>> Name:           draft-rodrigueznatal-lisp-oam
>> Revision:       00
>> Title:          LISP-OAM (Operations Administration Management): Use
>> cases and requirements
>> Document date:  2014-07-04
>> Group:          Individual Submission
>> Pages:          13
>> URL:
>> http://www.ietf.org/internet-drafts/draft-rodrigueznatal-lisp-oam-00.txt
>> Status:         https://datatracker.ietf.org/
>> doc/draft-rodrigueznatal-lisp-oam/
>> Htmlized:       http://tools.ietf.org/html/draft-rodrigueznatal-lisp-oam-
>> 00
>>
>>
>> Abstract:
>>     This document describes Operations Administration and Management
>>     (OAM) use-cases and the requirements that they have towards the LISP
>>     architecture.
>>
>>
>>
>>
>> Please note that it may take a couple of minutes from the time of
>> submission
>> until the htmlized version and diff are available at tools.ietf.org.
>>
>> The IETF Secretariat
>>
>>
>>
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