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<p class="MsoNormal">Hi networking-sfc,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">At the latest IRC meeting [1] it was agreed to split TAP from the possible insertion modes (initial spec version [2]).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I took the ARs to propose coexistence of insertion modes, correlation and (now) a new tap-enabled attribute, and send this email about possible directions.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here are my thoughts, let me know yours:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>My expectation for future PP and PPG if TAP+insertion modes go ahead and nothing else changes (only relevant details outlined):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt">port-pair (service-function-params):<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> correlation:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - MPLS<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - None (default)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt">port-pair-group (port-pair-group-params):<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> insertion-mode:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - L2<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - L3 (default)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> tap-enabled:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - False (default)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - True<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]>What I propose for future PP and PPG (only relevant details outlined):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt">port-pair (service-function-params):<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> <remove correlation – reasons outlined in [3] and below><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt">port-pair-group (port-pair-group-params):<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> mode:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - L2<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - L3 (default)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - MPLS<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - NSH<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> tap-enabled:<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - False (default)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:36.0pt"> - True<o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">With what’s proposed in 2.:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">- every combination will be possible with no clashes and no validation required.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">- port-pair-groups will always group “homogeneous” sets of port-pairs, making load-balacing and next-hop processing simpler and consistent.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">- the “forwarding” details of a Service Function are no longer dictated both by port-pair and port-pair-group, but rather only by port-pair-group.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">Are there any use cases for having next-hop SF candidates (individual port-pairs) supporting different SFC Encapsulation protocols?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">I understand, however, that removing correlation from port-pairs might not be ideal given that it’s a subtractive API change.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">[1] <a href="http://eavesdrop.openstack.org/meetings/service_chaining/2017/service_chaining.2017-03-16-17.02.html">
http://eavesdrop.openstack.org/meetings/service_chaining/2017/service_chaining.2017-03-16-17.02.html</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">[2] <a href="https://review.openstack.org/#/c/442195/">
https://review.openstack.org/#/c/442195/</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">[3] <a href="https://github.com/openstack/networking-sfc/blob/17c537b35d41a3e1fd80da790ae668e52cea6b88/doc/source/system_design%20and_workflow.rst#usage">
https://github.com/openstack/networking-sfc/blob/17c537b35d41a3e1fd80da790ae668e52cea6b88/doc/source/system_design%20and_workflow.rst#usage</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">Igor.<o:p></o:p></span></p>
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