Re: [nvo3] 答复: Comments on NVO3 data plane requirements for OAM

[Vero Zheng <[e-mail]>]

Hi Marc et.al,

I’m one of the co-authors/editors of the above-mentioned two drafts. Thanks for your interest in the marking mechanism.
By changing one or more bits of packets (header), data packets are marked into different blocks of markers without altering normal processing in the network.
No additional delimiting packet is needed and the performance can be measured in-service without the insertion of additional traffic.
The packet count/timestamp will be collected at the measurement point which correlated to certain blocks of marker and the loss/delay will be calculated.

BR,
Vero

From: nvo3 [mailto:[e-mail]] On Behalf Of Greg Mirsky
Sent: Wednesday, November 12, 2014 10:37 AM
To: Marc Binderberger
Cc: Haoweiguo; [e-mail]; Larry Kreeger
Subject: Re: [nvo3] 答复: Comments on NVO3 data plane requirements for OAM

Hi Marc,
thank you for your thorough review and thoughtful comments.
How passive performance measurement may work discussed in IP Flow Performance Measurement Framework <https://datatracker.ietf.org/doc/draft-chen-ippm-coloring-based-ipfpm-framework/> and IP Flow Performance Measurement Report<http://tools.ietf.org/html/draft-chen-ippm-ipfpm-report-00>.
I still believe that "original OAM flag" is to be used for active OAM, e.g. continuity check, proactive and on-demand, performance measurement. In some way, the GAL in MPLS is that "original OAM flag". But active OAM, IMO, should be complemented by use of passive measurement methods. Often these viewed as reading counters, IPFIX. But marking is method that expands and improves passive performance measurements through ability to correlate measurements taken at individual nodes along a path of the flow.
Regards,
Greg

On Tue, Nov 11, 2014 at 6:24 PM, Marc Binderberger <[e-mail]<mailto:[e-mail]>> wrote:
Hello Greg and Weiguo,

> agree with Weiguo, single bit flag in fixed position would be sufficient
> and HW-friendly.

a single bit just turns on and off - but it seems we have two different ideas
of OAM under discussion meanwhile. And both ideas claim they need an "OAM"
flag.

Makes already 2 bits :-)


> The NVO3 packet with this marking flag don't need to be sent to control
plane,
> it is different from OAM(ping/Trace) packet processing.

Really?  How is this working?  To do any processing of this real-time OAM you
still need to punt a copy of the NVO3 packet or at least the OAM-related
information to the generic CPU, i.e. get it out of the fast/hw forwarding
plane.


And then you need some information in the NVO3 packet, I assume?  Timestamps,
Counters etc.?  I don't think this will fit into any of the headers discussed
so far unless you use a TLV approach.


>> is precious. I would like it is set in fixed field, rather than in option
>> field. Because chipset normally can't process optional field, it is hard
>> to realize in-band performance measurement if using optional field for

If your optional field is defined to be the "first option TLV" then this is
no difference from a larger fixed header. Still not sure what the chipset is
supposed to process.

If the NVO3 group thinks this kind of OAM is sort of a must then of course it
makes sense to define the (fixed) base header with this OAM data. My problem
here is ...

>> marking. For other real time congestion control function, maybe more bits
>> are needed.

... that you already indicate there may be more/different OAM data in the
future. Using a fixed header likely means a new, larger fixed header to
incorporate the additional OAM, which makes older implementations
incompatible.


What the (fixed?) base header should support is the principle mechanism - we
seem to discuss a "punt, don't forward" and a "punt & forward" OAM, if I
understand it right (?).

At least the more "fancy" OAM seems a fit for optional TLV (with some
position restriction).


This initial OAM we are talking about here, is this just packet loss? So you
would need to carry some sequence number?



Regards, Marc





On Tue, 11 Nov 2014 16:04:30 -0800, Greg Mirsky wrote:
> Dear All,
> agree with Weiguo, single bit flag in fixed position would be sufficient
> and HW-friendly.
>
> Regards,
> Greg
>
> On Tue, Nov 11, 2014 at 3:51 PM, Haoweiguo <[e-mail]<mailto:[e-mail]>> wrote:
>> Hi Larry,
>> For marking purpose, i think one bit maybe OK, fixed fields in NVO3 header
>> is precious. I would like it is set in fixed field, rather than in option
>> field. Because chipset normally can't process optional field, it is hard
>> to realize in-band performance measurement if using optional field for
>> marking. For other real time congestion control function, maybe more bits
>> are needed.
>> Thanks
>> weiguo
>>
>> 发件人: Larry Kreeger (kreeger) [[e-mail]<mailto:[e-mail]>]
>> 发送时间: 2014年11月12日 4:33
>> 收件人: Haoweiguo; Greg Mirsky
>>
>> 抄送: [e-mail]<mailto:[e-mail]>
>> 主题: Re: [nvo3] Comments on NVO3 data plane requirements for OAM
>>
>>
>> Hi Weiguo,
>>
>> What do you envision this marking looking like?  e.g. is it just a single
>> flag bit, or large field with a counter or sequence number, or some kind
>> of flow ID?  If not a single flag, how large do you see the field being?
>>
>> If it is more than a flag (and I assume it would be), and is not mandatory
>> for all implementations, then it seems to fall into the category of
>> optional extensions.
>>
>> Thanks, Larry
>>
>> From: Haoweiguo <[e-mail]<mailto:[e-mail]>>
>> Date: Tuesday, November 11, 2014 10:18 AM
>> To: Greg Mirsky <[e-mail]<mailto:[e-mail]>>
>> Cc: "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
>> Subject: [nvo3] 答复: Comments on NVO3 data plane requirements for OAM
>>
>> Hi Greg,
>> I fully agree with you.
>> The real time OAM is passive performance measurement methods. I would like
>> NVO3 data encapsulation has a field for marking and not affect forwarding
>> of packets, the marking field is only used for performance measurement.
>> The NVO3 packet with this marking flag don't need to be sent to control
>> plane, it is different from OAM(ping/Trace) packet processing.
>> Thanks
>> weiguo
>>
>> 发件人: Greg Mirsky [[e-mail]<mailto:[e-mail]>]
>> 发送时间: 2014年11月12日 4:07
>> 收件人: Haoweiguo
>> 抄送: [e-mail]<mailto:[e-mail]>
>> 主题: Re: [nvo3] Comments on NVO3 data plane requirements for OAM
>>
>>
>> Hi Weiguo,
>> marking groups of packets that belong to the particular flow to facilitate
>> measurement of some performance metric, whether loss or delay/delay
>> variation, may be viewed as one of passive performance measurement
>> methods. But such marking should not alter, at least not significantly
>> alter, treatment of data flow in the network. Because of that, I believe,
>> OAM flag should not be used for marking as that will force punting marked
>> packets from fast forwarding path to the control plane. But it might be
>> good to have a field in NVO3 header that may be used for marking and not
>> affect forwarding of packets if altered.
>>
>> Regards,
>> Greg
>>
>> On Tue, Nov 11, 2014 at 12:34 AM, Haoweiguo <[e-mail]<mailto:[e-mail]>> wrote:
>>> Hi All,
>>> I maybe not clearly said in today’s NVO3 meeting, pls allow me to
>>> reiterate the OAM data plane requirements on the mail list.
>>> Currently NVO3 data plane encapsulation only includes one OAM flag, it is
>>> used for Ping/Trace similar applications. This kind of OAM application is
>>> initiated by operators for network connectivity verification, normally
>>> when network failure occurs. There is another OAM requirements of real
>>> time OAM or synthesizing OAM. It can be used for packet loss detection in
>>> real time. When ingress NVE receives traffic from local TS, it gets
>>> packet statistics, and mark(coloring) the OAM flag relying on local
>>> policy when it performs NVO3 encapsulation. When egress NVEs receives the
>>> traffic, it decapsulates NVO3 encapsulation, and gets packet statistics
>>> with the real time OAM flag marking. By comparing the packet number of
>>> ingress NVE and the sum of all egress NVEs, packet loss can be deduced.
>>> This method can be applicable for both unicast and multicast traffic.
>>> Local policy on ingress NVE is configured by operators or automatically
>>> acquired from centralized orchestration.
>>> Thanks
>>> weiguo
>>>
>>> _______________________________________________
>>> nvo3 mailing list
>>> [e-mail]<mailto:[e-mail]>
>>> https://www.ietf.org/mailman/listinfo/nvo3
>>>
>>
>>
>
>
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