56 lines
2.4 KiB
XML
56 lines
2.4 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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version="5.0"
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xml:id="software-defined-networking-sdn">
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<?dbhtml stop-chunking?>
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<title>Software-defined networking</title>
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<para>Software-defined networking (SDN) is the separation of the data
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plane and control plane. SDN is a popular method of
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managing and controlling packet flows within networks. SDN
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uses overlays or directly controlled layer-2 devices to
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determine flow paths, and as such presents challenges to a
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cloud environment. Some designers may wish to run their
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controllers within an OpenStack installation. Others may wish
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to have their installations participate in an SDN-controlled
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network.</para>
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<section xml:id="challenges-sdn">
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<title>Challenges</title>
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<para>SDN is a relatively new concept that is not yet
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standardized, so SDN systems come in a variety of different
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implementations. Because of this, a truly prescriptive
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architecture is not feasible. Instead, examine the differences
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between an existing and a planned OpenStack design and determine
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where potential conflicts and gaps exist.</para>
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</section>
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<section xml:id="possible-solutions-sdn">
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<title>Possible solutions</title>
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<para>If an SDN implementation requires layer-2 access because it
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directly manipulates switches, we do not recommend running an
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overlay network or a layer-3 agent. If the controller
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resides within an OpenStack installation, it may be necessary
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to build an ML2 plug-in and schedule the controller instances
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to connect to tenant VLANs that then talk directly to the
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switch hardware. Alternatively, depending on the external
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device support, use a tunnel that terminates at the switch
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hardware itself.</para>
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</section>
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<section xml:id="diagram-sdn">
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<title>Diagram</title>
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<para>OpenStack hosted SDN controller:
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<mediaobject>
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<imageobject>
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<imagedata fileref="../figures/Special_case_SDN_hosted.png"/>
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</imageobject>
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</mediaobject>
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</para>
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<para>OpenStack participating in an SDN controller network:
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<mediaobject>
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<imageobject>
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<imagedata fileref="../figures/Special_case_SDN_external.png"/>
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</imageobject>
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</mediaobject></para>
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</section>
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</section>
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