Thanks Greg for providing additional input to help make the model more extensible and reusable.
Please see my reply inline below.
-Qin
发件人: Greg Mirsky [mailto:gregimirsky@xxxxxxxxx]
发送时间: 2017年10月20日 20:34
收件人: ietf@xxxxxxxx; draft-ietf-lime-yang-connectionless-oam@xxxxxxxx
抄送: Carlos Pignataro; Ron Bonica; lime-chairs@xxxxxxxx; Benoit Claise; lime@xxxxxxxx
主题: Re: [Lime] Last Call: <draft-ietf-lime-yang-connectionless-oam-11.txt> (Generic YANG Data Model for Connectionless Operations, Administration, and Maintenance(OAM) protocols) to Proposed Standard
Dear All,
please kindly consider my comments on draft-ietf-lime-yang-connec
tionless-oam presented below:
- 1. Introduction
- clear and technical definitions of connection-oriented (CO) and connectionless (CL) network are absent. Note that referenced RFC 7276 does not provide that either as differentiation based on amount of configuration required to instantiate a network changes, decreases as result of further progress in network operation automation. I propose to use definitions CO and CL forwarding paradigms provided in section 6.3.1 G.800 Unified functional architecture of transport networks, as these are clear, technical and are broadly used in the industry.
[Qin]: I believe RFC7276 and G.800 share the similar paradigms but capture the different aspect of the key difference between CO and CL, I would suggest to harmonize the different aspect of these key differences together and add another reference to G.800 as follows:
NEW TEXT:
“
In connection-oriented technologies,
a connection is established prior to the transmission of data. After
connection is established, no additional control information such as
signaling or operations and maintenance information is required to
transmit the data. In connectionless technologies, data is
typically sent between end points without prior arrangement, but
control information is required to identify destination [G.800][RFC7276].
”
- characterization of the subject of the document as "YANG Data model for connectionless OAM protocols" is not accurate considering CO/CL definitions in G.800. I propose to refer to "OAM protocols for connectionless networks" since the same OAM protocols may be used in both CO-PS and CL-PS networks, e.g. LSP Ping used in both MPLS-TP and IP/MPLS networks.
[Qin]: Okay ,Sounds good to me.
- 3. Overview of the Connectionless OAM Model
- "... the 'test-point-location-info', is a common aspect of every 'test-point-location' - there's no YANG object test-point-location in the presented data model.
[Qin]: It is Typo. It should be ‘test-point-locations’, fixed. Thanks.
- 3.3 OAM Neighboring Layers
- I find this part of the model under-developed. First, the terminology - layers imply vertical, client-server relationship while downstream/upstream - peering relationship on the same layer. Second, the limited visibility due to technology-level limitation that supports only reference to the immediate neighboring layer but not to next-to-next neighbor. I consider this to be major problem for common model that intended for multi-layer environment.
[Qin]: We discussed this before, I revisit this section and understand your concern now , I would like to suggest to remove layer related text since it introduce confusion, I would suggest to change technology-level into position since what we try to define are OAM Neighboring Test points list. We will focus on test points related to one single layer. One can use position to capture of order of these test points and also identify test point at the left layer boundary and test point at the right layer boundary. The proposed changes as follows:
“
3.3. OAM neighboring test points
As typical networks have a multi-layer architecture, the set of OAM
protocols similarly take a multi-layer structure; each layer may has
its own OAM protocol [RFC7276] and is corresponding to specific
administrative domain and has associated test points. OAM
neighboring test points are referred to a list of neighboring test
points in the same layer that are related to current test point.
This allows users to easily navigate between related neighboring
layer to efficiently troubleshoot a defect. In this model,
'position' leaf defines the relative position of neighboring test
point corresponding to the current test point in the same layer , and
is provided to allow correlation of faults at different location . If
there is one neighboring test point placed before the current test
point, 'position' leaf is set to -1. If there is one neighboring
test point placed after the current test point, 'position' leaf is
set to 1. If there is no neighboring test point placed before or
after the current test point, 'position' leaf is set to 0.
list oam-neighboring-tps {
key "index";
leaf index {
type uint16 {
range "0..65536";
}
description
"Index of a list of neighboring test points
in the same layer ";
}
leaf position {
type int8 {
range "-1..1";
}
description
"The relative position
of neighboring test point
corresponding to the current
test point";
}
description
"List of related neighboring test points in the same layer.";
}
”
- 3.4 Test Point Locations Information
- reference to non-existent "tp-tool" and "OAM-neighboring Layers" groupings
[Qin]: It is typo, oam-neighboring layers should be corrected as “oam-neighboring-tps” now.
- 4. YANG OAM Model
- I think that use of prefix 'coam' for data model of OAM in connectionless networks is limiting considering that there should be another model of OAM in connection-oriented networks. Acronyms CL and CO usually used to refer to connectionless and connection-oriented networks respectively. Thus I suggest to use 'cl-oam' as prefix for the data model presented in this document and 'co-oam' instead of 'goam' in draft-ietf-lime-yang-connec
tion-oriented-oam-model. [Qin]:Good proposal, I like it.
- I find time-resolution to be superfluous and thus overcomplicating the model. I suggest use time-interval-type instead and consider for the update of yang:ietf-yang-types defined in RFC 6991.
[Qin]: Time resolution is referred to time unit, sure we can change it into time-interval-type as you suggested.
o session-delay-statistics and session-jitter-statistics are too limiting in many dimensions - no support to reflect one-way (far-end and near-end) and round-trip measurements for the same test session, and too few metrics., e.g. no report of percentile.[Qin]: We have protocol-id and protocol-id-meta-data to be defined in draft-ietf-lime-yang-connectionless-oam-methods-09 which can be used to indicate whether it is one way measurement, or two way measurements. Please see my reply for loss ration for report of percentile.o session-delay-statistics does not reflect type of delay variation being calculated. As analyzed in RFC 5481, PDV and IPDV characterize different conditions (Section 5) and at least reflecting which one being calculated and reported is very informative.[Qin]: We have protocol-id and protocol-id-meta-data to be defined in draft-ietf-lime-yang-connectionless-oam-methods-09 which can be used to indicate whether IPDV is used or PDV is used, Based on Brian’s suggestion, we could set IPDV as default for jitter measurement.o I cannot find anything that directly reports packet loss statistics (packet loss and packet loss ratio) for the given test session. Is that intentional? ICMP ping is capable to report number of lost packets in round-trip.[Qin]: We do have a parameter ‘packet-drops-count’ for packet-loss, we can change it into “packet-loss-count” as you suggested, in addition, we can add a new parameter for packet loss ration as follows:“leaf packet-loss-count {
type uint32 {
range "0..4294967295";
}
default "0";
description
"Total received packet drops count.
If the value is 4294967295, it indicates
packet drops count is overrun.";
}
leaf loss-ratio{
type uint8{
range 0..100; }
description
"Loss ratio of the packets. Express as percentage
of packets lost with respect to packets sent.";
}
”
[Qin]:Good point, we will remove to use 0 to indicate the parameter is not being reported.o connectionless-oam-layers - what considerations were discussed to arrive to liming number of neighboring test points to 128?[Qin]: Okay, we can change uint8 into uint16 to support more test points that can be recorded. But please note that each test point actually only record his neighboring test points, if each test points record a completeList of test points in one test, that will result in a lot of duplicated data associated with each test point.o tp-tools:continuity-check you may add RFC 8029 to the list of references[Qin]: Accepted, thanks.o tp-tools:path-discovery RFC 8029 obsoletes RFC 4379 as standard for LSP Ping[Qin]: Accepted, thanks.o timestamp grouping is limited to PTPv2 Truncated and NTPv4 64-bit format [RFC5905]. What about other formats, e.g. ICMP Timestamp, NTPv4 32-bit, a.k.a. short, or PTPv2 80-bits long?[Qin]: Here is the proposed change to address your comments:“grouping timestamp {
description
"Grouping for timestamp.";
leaf timestamp-type {
type identityref {
base timestamp-type;
}
description
"Type of Timestamp, such as Truncated PTP, NTP.";
}
container timestamp-64bit {
when "derived-from-or-self(../type, 'cl-oam:truncated-ptp')"+
"or derived-from-or-self(../type,'
cl-oam:ntp64')" { description
"Only applies when Truncated NTP or 64bit NTP Timestamp.";
}
leaf timestamp-sec {
type uint32;
description
"Absolute timestamp in seconds as per IEEE1588v2
or seconds part in 64-bit NTP timestamp.";
}
leaf timestamp-nanosec {
type uint32;
description
"Fractional part in nanoseconds as per IEEE1588v2
or Fractional part in 64-bit NTP timestamp.";
}
description
"Container for 64bit timestamp.";
}
container timestamp-80bit {
when "derived-from-or-self(../type, 'cl-oam:ptp80')"{
description
"Only applies when 80bit PTP Timestamp.";
}
if-feature ptp-long-format;
leaf timestamp-sec {
type uint64 {
range "0..281474976710656";
}
description
"48bit Timestamp in seconds as per IEEE1588v2.";
}
leaf timestamp-nanosec {
type uint32;
description
"Fractional part in nanoseconds as per IEEE1588v2
or Fractional part in 64-bit NTP timestamp.";
}
description
"Container for 64bit timestamp.";
}
container ntp-timestamp-32bit {
when "derived-from-or-self(../type, 'cl-oam:truncated-ntp')"{
description
"Only applies when 32 bit NTP Short format Timestamp.";
}
if-feature ntp-short-format;
leaf timestamp-sec {
type uint16;
description
"Timestamp in seconds as per short format NTP.";
}
leaf timestamp-nanosec {
type uint16;
description
"Truncated Fractional part in 16-bit NTP timestamp.";
}
description
"Container for 64bit timestamp.";
}
container icmp-timestamp-32bit {
when "derived-from-or-self(../type, 'cl-oam:icmp-ntp')"{
description
"Only applies when Truncated NTP or 64bit NTP Timestamp.";
}
if-feature icmp-timestamp;
leaf timestamp-millisec {
type uint32;
description
"timestamp in milliseconds for ICMP timestamp.";
}
description
"Container for 32bit timestamp.";
}
}
”
- 5.1.1.2 Test point attributes extension
- reference to non-existing "test-point-location" list
[Qin]: Same typo as you mentioned above, it should be “test-point-locations”.
- 5.1.2 Schema Mount
- reference to non-existing "test-point-location" list
[Qin]: Same as above, fixed.
- 5.2.1.2 Test point attributes extension
- reference to non-existing "test-point-location" list
[Qin]: Same as above, fixed.
- 5.2.2 Schema Mount
- reference to non-existing "test-point-location" list
[Qin]: Same as above, fixed.
In summary, I find several serious issues with the current version of the data model presented in the document, e.g. use of 0 to indicate unreported parameter and underdeveloped layering model.
Regards,
Greg
On Wed, Oct 11, 2017 at 6:40 AM, The IESG <iesg-secretary@xxxxxxxx> wrote:
The IESG has received a request from the Layer Independent OAM Management in
the Multi-Layer Environment WG (lime) to consider the following document: -
'Generic YANG Data Model for Connectionless Operations, Administration,
and Maintenance(OAM) protocols'
<draft-ietf-lime-yang-connectionless-oam-11.txt> as Proposed Standard
The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@xxxxxxxx mailing lists by 2017-10-25. Exceptionally, comments may be
sent to iesg@xxxxxxxx instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.
Abstract
This document presents a base YANG Data model for connectionless
Operations Administration, and Maintenance(OAM) protocols. It
provides a technology-independent abstraction of key OAM constructs
for connectionless protocols. The base model presented here can be
extended to include technology specific details. This is leading to
uniformity between OAM protocols and support both nested OAM
workflows (i.e., performing OAM functions at different or same levels
through a unified interface) and interacting OAM workflows ( i.e.,
performing OAM functions at same levels through a unified interface).
The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-lime-yang-connec tionless-oam/
IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-lime-yang-connec tionless-oam/ballot/
No IPR declarations have been submitted directly on this I-D.
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