Re: [Rtg-ooam-dt] [nvo3] O-bit vs. OAM as Next Protocol (Re: Consensus call on encap proposals)

["Carlos Pignataro (cpignata)" <[e-mail]>]

Hi, Tom,

On Aug 9, 2016, at 3:14 PM, Tom Herbert <[e-mail]<mailto:[e-mail]>> wrote:

On Tue, Aug 9, 2016 at 12:02 PM, Carlos Pignataro (cpignata)
<[e-mail]<mailto:[e-mail]>> wrote:

On Aug 9, 2016, at 12:28 PM, Tom Herbert <[e-mail]<mailto:[e-mail]>> wrote:

On Tue, Aug 9, 2016 at 9:07 AM, Greg Mirsky <[e-mail]<mailto:[e-mail]>> wrote:
Hi Tom,
many thanks for the most informative response. I've added mu notes in-line
under tag GIM>>.

Regards, Greg

On Mon, Aug 8, 2016 at 5:44 PM, Tom Herbert <[e-mail]<mailto:[e-mail]>> wrote:

On Sun, Aug 7, 2016 at 7:02 PM, Greg Mirsky <[e-mail]<mailto:[e-mail]>> wrote:
Dear Authors of the VxLAN-GPE, GUE, and GENEVE,
all protocols under consideration use a bit flag rather than explicit
protocol type to indicate that payload is a test packet, i.e. active
OAM.
I'm trying to understand the rationale of such decision. Does use of the
bit
flag rather than protocol type produce more efficient implementation, is
more HW friendly? In GUE, the the field to indicate type of the payload
even
tagged Proto/ctype as its interpretation depends upon value of the C
bit.

The C-bit in GUE distinguishes data messages from control
messages.Data messages are considered to be the payload of
encapsulation, whereas control messages are about the encapsulation
itself. OAM might be one type of control message in GUE, however there
could be others. For instance if we wanted some sort of negotiation
between two endpoints to exchange capabilities or supported features
this would fit well into a control message.

GIM>> Yes, what I've proposed is clearly more than just OAM channel. In
fact, it is Associated Channel (ACh) that may be used by control, management
and OAM. And as I've used term "Associated Channel" you'll easily recognize
that I have MPLS background and draw on MPLS/MPLS-TP OAM experience. And as
Generic ACh (G-ACh) is used to advertise capabilities of an LSR in RFC 7212,
AC-h in NVO3 can support similar functionalities as well.


But wouldn't it be simpler if all proposals used protocol type to
identify
OAM payload? And if the protocol type is OAM, then after the protocol
header
have OOAM Header, e.g. as proposed in . Then

Each of the three protocols has a protocol next header field, however
the field is defined differently among them. The next header in GUE is
an IP protocol number, in Geneve it is an Ethertype, and VXLAN-GPE
uses a new number space. In GUE we could probably use ICMP protocol
for OAM by defining the appropriate types (that might have the
advantage of allow OAM to be generic instead of restricted to only
encapsulation). Presumably, VXLAN-GPE could define some value in the
number space for for OAM. For Geneve maybe there is an appropriate
Ethertype?

NVO3 protocols would be able to have common Active OAM (Fault Management
and
Performance Measurement) that can be used in BIER and SFC. And the bit,
the
bit I'd propose to redefine to be used for passive performance
measurement
as described in draft-ietf-bier-pmmm-oam. (Allocating two bits-long
field
would enable more accurate measurements using the Alternate Marking
method).
And these steps will enable us to develop common Active OAM and use
passive
performance measurement regardless, almost, of the data plane protocol
used
in NVO layer.

The problem I see with trying to constrain the solution to only one or
two bits of information is that this substantially limits the
functionality. With an extensible protocol we should be able more
information to get more accurate measurement. For instance, I might
want to measure the latency of individual packets to get feedback on
path selection, correlate performance to packet loss, etc. Has the OAM
DT considered the requirements and solutions for passive performance
measurement?

GIM>> Indeed, the OAM DT had considered the requirements to enable use of
performance measurement methods as passive OAM. Should note that we use term
"passive method" somewhat differently from the definition in RFC 7799. Such
interpretation was discussed in the IPPM WG and we've agreed that if a
measurement method does not change treatment of a data packet by the network
(e.g. doesn't change its CoS, length or else), then the method behaves as
close as passive and may be characterized as such. Measurements for a single
packet are possible using the Alternate Marking method with two bits-long
marker. The draft in BIER WG has such example. I've attached the
presentation slides. Will be glad to answer any further questions.

Yes, but number of specific packets I could measure is still limited
in some time quantum with the two bit method. Alternatively, if every
packet contained a timestamp for instance, then we can measure every
packet and filter or aggregate the measurements with arbitrary
granularity of our choosing.

Indeed, as for example at draft-brockners-inband-oam-data-01. This is a measurement that is neither “active” nor “passive” based on the IETF definitions (where active means a probe, and passive means no change whatsoever to a packet).

Carlos,

Thanks for the pointer, that looks like a good basis for an extensible
and generic OAM inband measurement mechanism. I assume for IPv6 this
would be appropriate as options in HBH extension headers, have you
defined the formats for that?

Thanks — and you are exactly right:
https://tools.ietf.org/html/draft-brockners-inband-oam-transport-01#section-3

This was demoed as IPv6 edge to edge in Bits-n-Bites in Berlin.

Thanks,

— Carlos.


Thanks,
Tom

BIER may have been defined with as a
fixed length header so that a couple of bits are all that could
feasibly be allocated to OAM, but this is not necessarily true for
other encapsulation protocols that are purposely extensible to support
a richer set of features.

Agreed as well.

Thanks,

— Carlos.


Tom



Thanks,
Tom


Regards, Greg

On Fri, Jul 29, 2016 at 8:13 AM, Alia Atlas <[e-mail]<mailto:[e-mail]>> wrote:

I'd like to have people focus on the key point of this thread.

Are there serious technical objections (and specifically what are they)
to
moving forward with VXLAN-GPE as the standards-track protocol?

Are there serious technical objections (and specifically what are they)
to
moving forward with GENEVE as the standards-track protocol?

Are there serious technical objections (and specifically what are they)
to
moving forward with GUE as the standards-track protocol?

We need to capture any relevant objections.  So far, there's been some
discussion on extensibility - with Tom Herbert providing concrete
concerns.

I have concluded that almost all the authors would prefer to have no
standards track solution if they can't guarantee that theirs is that
standard.

I do hear concerns about whether a decision will be too late.   I think
that a decision can only be helpful.   It goes back to when is the best
time
to plant a tree - with the answer of 20 years ago or now.

Regards,
Alia


On Fri, Jul 29, 2016 at 4:34 AM, Naoki Matsuhira
<[e-mail]<mailto:[e-mail]>> wrote:



On 2016/07/21 23:56, Bocci, Matthew (Nokia - GB) wrote:

WG

There was a discussion in the NVO3 WG meeting in Berlin following
strong
advice from our Area Director that we need to come to a consensus on
converging on a common encapsulation. Two sets of questions were
asked:
(1) Should the WG move forward with one standards track encap?
(2) For a given encap, do you have significant technical objections?


I want to inform to this mailing list that I proposed ME6E-FP and
ME6E-PR
at the yokohama meeting. I also have proposal M46E-FP and M46E-PR
(past
called SA46T).

These encapsulation technologies are based on address mapping. ME6E
use
IPv6 address which mapping MAC address, and M46E use IPv6 address
which
mapping IPv4 address.

I understand too many encapsulation technologies, however these my
proposal are simple, and may contribute to the Internet.

I believe address mapping approach is unique, so I want to propose
again.

sorry not the answer to the question.

Naoki Matsuhira


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