Subject: [Detnet] Changes to IP data plane document based on Oct 14 Call

From: Lou Berger <[email-masked]>
Date: Mon, 14 Oct 2019 09:09:29 -0400

Hi,

     David Black joined the on going data plane weekly call and we came 
up with some changes to the language previously discussed on the list.  
The changes are capture in the following commit and diff.  The full 
document text can be seen at 
https://xml2rfc.tools.ietf.org/cgi-bin/xml2rfc.cgi?url=https://raw.githubusercontent.com/detnet-wg/data-plane-drafts/master/ip/draft-ietf-detnet-ip.xml 

Please send comments if you have them.

https://github.com/detnet-wg/data-plane-drafts/pull/56/commits/d3a733556804f11abbedbd128e3c62786418ddc8

diff --git a/ip/draft-ietf-detnet-ip.xml b/ip/draft-ietf-detnet-ip.xml
index afadf9b..124af58 100644
--- a/ip/draft-ietf-detnet-ip.xml
+++ b/ip/draft-ietf-detnet-ip.xml
@@ -387,6 +387,8 @@
            e.g., buffers, to receive and process a DetNet flow packets.
          </t>
          <t>
+          In order to maximize reuse of 5-tuple based mechanisms, e.g,
+          traceroute,
            DetNet aware applications and end systems SHOULD NOT mix
            DetNet and non-DetNet traffic within a single 5-tuple.
          </t>
@@ -526,6 +528,13 @@ DetNet                    |L2/SbN| |L2/SbN|
                (L4) transport protocols or application protocols. 
However, these
                protocols are out of scope of this document.
              </t>
+            <t>
+              Note that not mixing DetNet and non-DetNet traffic within
+              a single 5-tuple, as described above, enables simpler
+              5-tuple filters to be reused at the edges of a DetNet
+              network to prevent non-congestion responsive DetNet
+              traffic from escaping the DetNet domain.
+            </t>
        </section>

        <section title="Forwarding Sub-Layer Considerations">
@@ -593,16 +602,19 @@ DetNet                    |L2/SbN| |L2/SbN|
            In non-DetNet IP forwarding, it is generally assumed that the
            same series of next hops, i.e., the same path, will be used
            for a particular 5-tuple or, in some cases, e.g., <xref
-          target="RFC5120"/>, for a particular 6-tuple.  This assumption
-          is reflected in higher protocol levels, e.g., see <xref
-          target="RFC3168"/>. Using different next hops for different
-          5-tuples does not take any special consideration within a
-          DetNet domain.  Care should be taken when using different next
-          hops for the same 5-tuple. Understanding of the application
-          and transport protocol impact of using different next
-          hops for the same 6-tuple is required. Again, this impacts
-          path selection for DetNet flows and this document only
-          indirectly.
+          target="RFC5120"/>, for a particular 6-tuple.  Using different
+          next hops for different 5-tuples does not take any special
+          consideration for DetNet aware applications.
+        </t>
+        <t>
+          Care should be taken when using different next hops for the
+          same 5-tuple.  As discussed in <xref target="RFC7657"/>,
+          unexpected behavior can occur when a single 5-tuple
+          application flow experience reordering due to being split
+          across multiple next hops.  Understanding of the application
+          and transport protocol impact of using different next hops for
+          the same 6-tuple is required.  Again, this impacts path
+          selection for DetNet flows and this document only indirectly.
          </t>
        </section>

Lou (as contributor)