Subject: [ippm] OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

From: "MORTON, ALFRED C (AL)" <[email-masked]>
Date: Mon, 19 Oct 2015 17:13:13 -0400

OPS-DIR, Authors, 

I have reviewed this document as part of the Operational directorate's 
ongoing effort to review all IETF documents being processed by the IESG.  
These comments were written primarily for the benefit of the operational 
area directors. Document editors and WG chairs should treat these comments 
just like any other last call comments.

Al

Title:
Differentiated Service Code Point and Explicit Congestion Notification
       Monitoring in Two-Way Active Measurement Protocol (TWAMP)
                   draft-ietf-ippm-type-p-monitor-02
https://tools.ietf.org/html/draft-ietf-ippm-type-p-monitor-02

Summary: Almost ready, comments and editorial suggestions follow.

The draft header should indicate that this draft updates RFC 5357.

Section 2.2.1

Figure 1 has a number of canonical references that should 
be cited to ensure IPv4 and IPv6 applicability, including 
RFC 2474, RFC 3168, and other relevant updates (of which 
there are many).

<later>
   o  if the negotiated/provisioned DSCP value is not known (e.g.  TWAMP
      Light), the choice of the DSCP is implementation specific.  For
      instance, Session-Reflector MAY copy the DSCP value from the
      received test packet and set it as DSCP in a reflected packet.
Question:
What about the ECN value?   From 3168:
      +-----+-----+
      | ECN FIELD |
      +-----+-----+
        ECT   CE         [Obsolete] RFC 2481 names for the ECN bits.
         0     0         Not-ECT
         0     1         ECT(1)
         1     0         ECT(0)
         1     1         CE
It makes little sense to copy a "11" == CE into the reflected packet,
and it may affect the measured performance if "11" were copied.
The draft needs more guidance here (there is a general problem
when the negotiated values are "not known"; this does not apply 
to the Standards Track TWAMP protocol or its extensions).

-=-=-=-=-=-=-=-=-=-=-=-=-

Editorial comments/suggestions:

OLD
2.2.  TWAMP-Test Extension

   Monitoring of DSCP and ECN requires support by the Session-Reflector
   and changes the format of its test packet format both in
   unauthenticated, authenticated and encrypted modes. 
Suggest:
   Monitoring of DSCP and ECN requires support by the Session-Reflector
   and changes the test packet format in all the original
   (unauthenticated, authenticated and encrypted) modes. 

2.2.1

OLD
   o  the first six bits of the Differentiated Service field MUST be
      copied from received Session-Sender test packet into Sender DSCP
      (S-DSCP) field;

   o  the following two bits of the ECN field MUST be copied from
      received Session-Sender test packet into Sender ECN (S-ECN) field.
Suggest:
   o  the six (least-significant) bits of the Differentiated Service field MUST be
      copied from received Session-Sender test packet into Sender DSCP
      (S-DSCP) field;

   o  the two bits of the ECN field MUST be copied from
      received Session-Sender test packet into Sender ECN (S-ECN) field.

because RFC 3168 defines:
         0     1     2     3     4     5     6     7
      +-----+-----+-----+-----+-----+-----+-----+-----+
      |          DS FIELD, DSCP           | ECN FIELD |
      +-----+-----+-----+-----+-----+-----+-----+-----+

        DSCP: differentiated services codepoint
        ECN:  Explicit Congestion Notification

      Figure 2: The Differentiated Services and ECN Fields in IP.
-=-=-=-=-=-=-=-

OLD
    0     1     2     3     4     5     6     7     8
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               S-DSCP              |   S-ECN   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: Sender DSCP and ECN field format

Suggest:
The extra "+" within bit positions are distracting,
and don't conform to the conventions of these diagrams.
Also, there's no "8" when numbering from 0.

Some attempt should be made to put Figure 3 on a single page in the 
final version. There's one line taken up by "+" that is unnecessary
in the modified field:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Sender TTL  |  S-DSCP-ECN   |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
    |                                                             |
 >> +                                                             + <<
    |                       MBZ (14 octets)                       |
    |                                                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

---

From: Gregory Mirsky <[email-masked]>
Date: Tue, 20 Oct 2015 20:25:48 +0000

Dear Al,
thank you for your thorough review and thoughtful comments. We're working on addressing them and will send proposed updates shortly.

        Regards,
                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

I have reviewed this document as part of the Operational directorate's ongoing effort to review all IETF documents being processed by the IESG.
These comments were written primarily for the benefit of the operational area directors. Document editors and WG chairs should treat these comments just like any other last call comments.

Al

Title:

Section 2.2.1

<later>

OLD

2.2.1

OLD

OLD
    0     1     2     3     4     5     6     7     8

Suggest:

    |                       MBZ (14 octets)                       |
    |                                                             |

---

From: "MORTON, ALFRED C (AL)" <[email-masked]>
Date: Wed, 21 Oct 2015 21:35:24 -0400

Hi Greg,

I don’t think you addressed this comment:

If you need help with the XML formatting to do this,
let me know.

In the draft, the section that moved needs a bit more
editing, IMO:

                   The DSCP value is often copied into reflected test packets with
                  current TWAMP implementations (with or without TWAMP-Control
I would claim this is only
true for the “without control” case,
so s/with or without/without/
( I must have read this as “without”
previously, I have knowledge of many
deployed TWAMP nodes.)

                  protocol).  With DSCP and ECN Monitoring Extension, the Session-
                  Reflector handles DSCP as following:

                   o  the Session-Reflector MUST extract the S-DSCP-ECN value from the
                     DSCP and ECN values of received packets;

                   o  the Session-Reflector MUST transmit each reflected test packet
                     with DSCP set to the negotiated/provisioned value;

                   o  ECN SHOULD be set to Not-ECT codepoint value [RFC3168].

I think this (new) last bullet needs to read:
o  if the negotiated/provisioned ECN value is not known,
   ECN SHOULD be set to Not-ECT codepoint value [RFC3168].
   Otherwise, the provisioned ECN value for the session SHALL be used.

hope this helps,
Al

From: Gregory Mirsky [mailto:[email-masked]]
Sent: Wednesday, October 21, 2015 6:19 PM
To: MORTON, ALFRED C (AL); [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Subject: RE: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

Dear Al,

thank you for your thorough review and thoughtful comments. I've prepared the new version to respond to all comments but from Kathleen Moriarty (need some extra time).

Would greatly appreciate your review of the changes and hope that these address your comments.

Please find my answers below in-line and tagged GIM>>.

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

ECN SHOULD be set to Not-ECT codepoint value [RFC3168].

OLD

Suggest:

GIM≫ Thank you, accepted.

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

GIM≫ Thank you. Accepted.

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7
    +---+---+---+---+---+---+---+---+
    |         S-DSCP        | S-ECN |
    +---+---+---+---+---+---+---+---+

in the modified field:

GIM≫ That turned to be rather difficult, considering that the original figure in RFC 5357 is over one page already. I've tried to move figure to the very top though.

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |

---

From: Gregory Mirsky <[email-masked]>
Date: Thu, 22 Oct 2015 01:43:02 +0000

Hi Al,
yes, forgot about that comment. I do need help with the XML and greatly appreciate your help.

I’ll work on addressing other suggestions.

                Regards,
                                Greg

From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Wednesday, October 21, 2015 6:35 PM
To: Gregory Mirsky; [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Subject: RE: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

Hi Greg,

hope this helps,
Al

To: MORTON, ALFRED C (AL); [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>

Dear Al,

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

OLD

Suggest:

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7

in the modified field:

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |

---

From: "MORTON, ALFRED C (AL)" <[email-masked]>
Date: Wed, 21 Oct 2015 21:51:18 -0400

You can probably find a line similar to this, just before <front>:

<rfc category="info" docName="draft-morton-ippm-2330-stdform-typep-01"
     ipr="trust200902" updates="2330">
  <front>

From: ippm [mailto:[email-masked]] On Behalf Of Gregory Mirsky
Sent: Wednesday, October 21, 2015 9:43 PM
To: MORTON, ALFRED C (AL); [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Subject: Re: [ippm] OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

Hi Al,

                Regards,
                                Greg

To: Gregory Mirsky; [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>

Hi Greg,

hope this helps,
Al

Dear Al,

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

OLD

Suggest:

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7

in the modified field:

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |

---

From: Gregory Mirsky <[email-masked]>
Date: Thu, 22 Oct 2015 01:52:57 +0000

Many thanks!

Sent: Wednesday, October 21, 2015 6:51 PM

Hi Al,

                Regards,
                                Greg

Hi Greg,

hope this helps,
Al

Dear Al,

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

OLD

Suggest:

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7

in the modified field:

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |

---

From: Gregory Mirsky <[email-masked]>
Date: Thu, 22 Oct 2015 02:14:46 +0000

Hi Al,
thank you for your help with the XML and proposed clarifications. Below please find my proposal to one update you’ve suggested under GIM-2>> tag.
I’ll wait for responses from other reviewers to include their comments.

                Regards,
                                Greg

Hi Greg,

GIM-2>>   The DSCP value is often copied into reflected test packets with
   current TWAMP implementations without TWAMP-Control protocol.

GIM-2>> Yes, agreed.

hope this helps,
Al

Dear Al,

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Cc: [email-masked]<mailto:[email-masked]>; [email-masked]<mailto:[email-masked]>
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

OLD

Suggest:

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7

in the modified field:

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |

---

From: Gregory Mirsky <[email-masked]>
Date: Wed, 21 Oct 2015 22:19:21 +0000

Dear Al,

                Regards,

                                Greg

-----Original Message-----
From: MORTON, ALFRED C (AL) [mailto:[email-masked]]
Sent: Monday, October 19, 2015 2:13 PM
To: [email-masked]; [email-masked]
Cc: [email-masked]; [email-masked]
Subject: OPS-DIR Review: draft-ietf-ippm-type-p-monitor-02

OPS-DIR, Authors,

Al

Title:

Section 2.2.1

there are many).

<later>

Question:

      +-----+-----+

      | ECN FIELD |

      +-----+-----+

         0     0         Not-ECT

         0     1         ECT(1)

         1     0         ECT(0)

         1     1         CE

GIM>> Added

OLD

Suggest:

2.2.1

OLD

      (S-DSCP) field;

Suggest:

      (S-DSCP) field;

         0     1     2     3     4     5     6     7

-=-=-=-=-=-=-=-

OLD

    0     1     2     3     4     5     6     7     8

    |               S-DSCP              |   S-ECN   |

Suggest:

GIM≫ Agree. New version:

      0   1   2   3   4   5   6   7

in the modified field:

    |                                                             |

    |                       MBZ (14 octets)                       |

    |                                                             |