Re: [Ioam] Internal WG Review: In-situ OAM (ioam)

[Stewart Bryant <[e-mail]>]

On 09/02/2017 19:30, Carlos Pignataro (cpignata) wrote:
> Hi, Stewart,
>
> Many thanks for the comments, please see inline.
>
>> On Feb 9, 2017, at 1:50 PM, Stewart Bryant <[e-mail]> wrote:
>>
>>
>>
>> On 09/02/2017 17:18, Carlos Pignataro (cpignata) wrote:
>>> Passive means ‘solely by observation and without modification to the packet’ (https://tools.ietf.org/html/draft-ietf-ippm-active-passive-06#section-3.6).
>> Carlos, that is not quit where we are going with passive. We use packet marking to batch the packets for loss measurement, and we are planning to trigger delay/jitter measurement through marking.
>>
> I’ll follow down this tangent for a bit.
>
> I understand and as you know I’m well aware of the (alternate) packet marking techniques and different methods.
>
> However, the *current* definition is quite unambiguous:
>
> https://tools.ietf.org/html/rfc7799#section-3.6
> “
> 3.6.  Passive Methods
>
>     Passive Methods of Measurement are:
>
>     o  based solely on observations of an undisturbed and unmodified
>        packet stream of interest (in other words, the method of
>        measurement MUST NOT add, change, or remove packets or fields or
>        change field values anywhere along the path).
> “
>
> Since both those datapoints are rooted in IPPM, I’d suggest working through the definitions on IPPM and how marking fits (since it is not only on observation points)
>
> Now, bringing this back to the relevance of the In-situ OAM (ioam) charter, my only point is that In-situ OAM is neither passive nor active.

... and the point I make is that packet marking (which I think we have 
established is the only viable way of making accurate loss measurements 
in connectionless networking) is also neither active of passive 
according to these definitions.

>
>> As you know marking is much easier in MPLS that IP.
>>
>> I think the key distinguisher is really that in-situ is about embedding OAM meta-data in user data traffic.
> This is a good point.
>
> I agree.
>
> I believe this is already clear in the charter, all the way from the very first sentence:
>
> “ It is based on telemetry information which is embedded within live data packets.”
>
> Do you believe this is not clear in the charter? Do you have specific suggestions or concrete recommendations that can improve the charter text?

I suppose you could say: It is based on telemetry information which is 
embedded within live data packets and is distinct from packet parking 
methods being developed elsewhere in the IETF.

I have not thought it through, but I am wondering what distinguishes the 
packet types you list (IPv4, IPv6, VXLAN-GPE, LISP, NSH, SRv6, Geneve) 
from other packet types, the obvious one being MPLS. Not that I am at 
all keen on trying to get this into the simple fast forwarders we use 
for MPLS. In other words what is the generic class of packets you are 
targetting?

Stewart

>
> Thanks!
>
>> - Stewart
>
> —
> Carlos Pignataro, [e-mail]
>
> “Sometimes I use big words that I do not fully understand, to make myself sound more photosynthesis."
>