Subject: Alia Atlas' Discuss on draft-ietf-bfd-seamless-ip-04: (with DISCUSS)

From: "Alia Atlas" <[email-masked]>
Date: Mon, 02 May 2016 15:26:27 -0700

Alia Atlas has entered the following ballot position for
draft-ietf-bfd-seamless-ip-04: Discuss

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DISCUSS:
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I think that these are both simple fast issues to resolve.

1) Sec 3: "This document defines only the UDP port value
   for the S-BFD Echo function.  The source port and the procedures for
   the S-BFD Echo function are outside the scope of this document."
Please add a reference to the S-BFD base document for defining where the
procedures are found. 

Where, precisely, is the source port defined?  It wasn't in the S-BFD
base
document.  This seems like a hole.  Can you please clarify?

2) Sec 4:  " If the port is not 7784, then the packet MUST be looked up
to locate
   a corresponding SBFDInitiator session or classical BFD session based
   on the value from the "your discriminator" field in the table
   describing BFD discriminators. "

I assume that you mean that UDP source port is used to look up the
appropriate receiver.
If that receiver handles BFD and S-BFD packets, then the "your
discriminator" field is used
to identify the BFD session.   PLEASE clarify that because this reads as
if BFD is the only
application that uses UDP.

---

From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Mon, 2 May 2016 23:22:28 +0000

Hi Alia,

Thanks for the review and for these! Please see inline.

> On May 2, 2016, at 6:26 PM, Alia Atlas <[email-masked]> wrote:
> 

This is done exactly as in RFC 5881, purposefully. I can add a clarifying sentence like:

OLD:
   This document defines only the UDP port value
   for the S-BFD Echo function.  The source port and the procedures for
   the S-BFD Echo function are outside the scope of this document.

NEW:
   S-BFD echo follows the BFD echo definitions of [RFC 5881].
   Consequently, this document defines only the UDP port value
   for the S-BFD Echo function; the source port and the procedures for
   the S-BFD Echo function are outside the scope of this document.

> application that uses UDP.

Indeed, very much so. I suggest:

OLD:
   If the port is not 7784, then the packet MUST be looked up to locate
   a corresponding SBFDInitiator session or classical BFD session based
   on the value from the "your discriminator" field in the table
   describing BFD discriminators.  If the located session is an
   SBFDInitiator, then the destination IP address of the packet SHOULD
   be validated to be for self.  If the packet is a classical BFD
   session, then the procedures from [RFC5880] apply.

NEW:
   If the port is not 7784, but the packet is demultiplexed to be for an
   SBFDInitiator, then the packet MUST be looked up to locate
   a corresponding SBFDInitiator session based
   on the value from the "your discriminator" field in the table
   describing BFD discriminators.  In that case,
   then the destination IP address of the packet SHOULD
   be validated to be for itself.  If the packet demultiplexes to a classical BFD
   session, then the procedures from [RFC5880] apply.

Would that work?

Thanks,

— Carlos.

---

From: Alia Atlas <[email-masked]>
Date: Tue, 3 May 2016 12:30:45 -0400

Hi Carlos,

On Mon, May 2, 2016 at 7:22 PM, Carlos Pignataro (cpignata) <
[email-masked]> wrote:

> > Please refer to
> https://www.ietf.org/iesg/statement/discuss-criteria.html

How about a reference by the source port to [RFC 5881] and a reference
for the procedures for the S-BFD Echo function
[draft-ietf-bfd-seamless-base]?

What wasn't clear to me - not having recently read RFC 5881 in detail - was
that the UDP source port was defined in RFC 5881.  I knew the procedures
were
in draft-ietf-bfd-seamless-base.

>    session, then the procedures from [RFC5880] apply.

Sure - sounds good.  Thanks,
Alia

---

From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Tue, 3 May 2016 16:53:27 +0000

Hi, Alia,

Thanks, and sounds good. This is what we have implemented, which should address both:

@@ -122,9 +122,9 @@
    The BFD Echo port defined by [RFC5881], port 3785, is used for the
    S-BFD Echo function on IPv4, IPv6 and MPLS environments.
    SBFDInitiator sessions MUST transmit S-BFD echo packets with
-   destination port 3785.  This document defines only the UDP port value
-   for the S-BFD Echo function.  The source port and the procedures for
-   the S-BFD Echo function are outside the scope of this document.
+   destination port 3785.  The setting of the UDP source port [RFC5881]
+   and the procedures [I-D.ietf-bfd-seamless-base] for the S-BFD Echo
+   function are outside the scope of this document.

 4.  S-BFD Control Packet Demultiplexing

@@ -138,13 +138,13 @@
    S-BFDReflector), then the packet MUST be looked up to locate a
    corresponding SBFDReflector session based on the value from the "your
    discriminator" field in the table describing S-BFD discriminators.
-   If the port is not 7784, then the packet MUST be looked up to locate
-   a corresponding SBFDInitiator session or classical BFD session based
-   on the value from the "your discriminator" field in the table
-   describing BFD discriminators.  If the located session is an
-   SBFDInitiator, then the destination IP address of the packet SHOULD
-   be validated to be for self.  If the packet is a classical BFD
-   session, then the procedures from [RFC5880] apply.
+   If the port is not 7784, but the packet is demultiplexed to be for an
+   SBFDInitiator, then the packet MUST be looked up to locate a
+   corresponding SBFDInitiator session based on the value from the "your
+   discriminator" field in the table describing BFD discriminators.  In
+   that case, then the destination IP address of the packet SHOULD be
+   validated to be for itself.  If the packet demultiplexes to a
+   classical BFD session, then the procedures from [RFC5880] apply.

 5.  Initiator Procedures

@@ -165,7 +165,7 @@

Thanks,

— Carlos.

> On May 3, 2016, at 12:30 PM, Alia Atlas <[email-masked]> wrote:
> 
> Hi Carlos,
> 
> On Mon, May 2, 2016 at 7:22 PM, Carlos Pignataro (cpignata) <[email-masked] <mailto:[email-masked]>> wrote:
> Hi Alia,
> 
> > On May 2, 2016, at 6:26 PM, Alia Atlas <[email-masked] <mailto:[email-masked]>> wrote:
> >
> > Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html <https://www.ietf.org/iesg/statement/discuss-criteria.html>
> > https://datatracker.ietf.org/doc/draft-ietf-bfd-seamless-ip/ <https://datatracker.ietf.org/doc/draft-ietf-bfd-seamless-ip/>
> >
> >
> >
> for the procedures for the S-BFD Echo function [draft-ietf-bfd-seamless-base]?
> 
> that the UDP source port was defined in RFC 5881.  I knew the procedures were

---

From: Alia Atlas <[email-masked]>
Date: Tue, 3 May 2016 12:56:44 -0400

LGTM