180 lines
8.5 KiB
XML
180 lines
8.5 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<chapter 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="network_focus">
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<title>Network focused</title>
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<para>All OpenStack deployments are dependent, to some extent, on
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network communication in order to function properly due to a
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service-based nature. In some cases, however, use cases
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dictate that the network is elevated beyond simple
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infrastructure. This chapter is a discussion of architectures
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that are more reliant or focused on network services. These
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architectures are heavily dependent on the network
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infrastructure and need to be architected so that the network
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services perform and are reliable in order to satisfy user and
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application requirements.</para>
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<para>Some possible use cases include:</para>
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<variablelist>
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<varlistentry>
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<term>Content delivery network</term>
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<listitem>
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<para>This could include
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streaming video, photographs or any other cloud based
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repository of data that is distributed to a large
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number of end users. Mass market streaming video will
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be very heavily affected by the network configurations
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that would affect latency, bandwidth, and the
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distribution of instances. Not all video streaming is
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consumer focused. For example, multicast videos (used
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for media, press conferences, corporate presentations,
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web conferencing services, and so on) can also utilize a
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content delivery network. Content delivery will be
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affected by the location of the video repository and
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its relationship to end users. Performance is also
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affected by network throughput of the backend systems,
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as well as the WAN architecture and the cache
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methodology.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Network management functions</term>
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<listitem>
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<para>A cloud that provides
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network service functions would be built to support
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the delivery of back-end network services such as DNS,
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NTP or SNMP and would be used by a company for
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internal network management.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Network service offerings</term>
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<listitem>
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<para>A cloud can be used to
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run customer facing network tools to support services.
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For example, VPNs, MPLS private networks, GRE tunnels
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and others.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Web portals or web services</term>
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<listitem>
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<para>Web servers are a common
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application for cloud services and it is recommended
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to have an understanding of the network requirements.
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The network will need to be able to scale out to meet
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user demand and deliver webpages with a minimum of
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latency. Internal east-west and north-south network
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bandwidth must be considered depending on the details
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of the portal architecture.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>High speed and high volume transactional systems</term>
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<listitem>
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<para>
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These types of applications are very sensitive to
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network configurations. Examples include many
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financial systems, credit card transaction
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applications, trading and other extremely high volume
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systems. These systems are sensitive to network jitter
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and latency. They also have a high volume of both
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east-west and north-south network traffic that needs
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to be balanced to maximize efficiency of the data
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delivery. Many of these systems have large high
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performance database back ends that need to be
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accessed.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>High availability</term>
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<listitem>
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<para>These types of use cases are
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highly dependent on the proper sizing of the network
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to maintain replication of data between sites for high
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availability. If one site becomes unavailable, the
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extra sites will be able to serve the displaced load
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until the original site returns to service. It is
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important to size network capacity to handle the loads
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that are desired.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Big data</term>
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<listitem>
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<para>Clouds that will be used for the
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management and collection of big data (data ingest)
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will have a significant demand on network resources.
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Big data often uses partial replicas of the data to
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maintain data integrity over large distributed clouds.
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Other big data applications that require a large
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amount of network resources are Hadoop, Cassandra,
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NuoDB, RIAK and other No-SQL and distributed
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databases.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Virtual desktop infrastructure (VDI)</term>
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<listitem>
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<para>This use case
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is very sensitive to network congestion, latency,
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jitter and other network characteristics. Like video
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streaming, the user experience is very important
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however, unlike video streaming, caching is not an
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option to offset the network issues. VDI requires both
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upstream and downstream traffic and cannot rely on
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caching for the delivery of the application to the end
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user.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Voice over IP (VoIP)</term>
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<listitem>
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<para>This is extremely sensitive to
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network congestion, latency, jitter and other network
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characteristics. VoIP has a symmetrical traffic
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pattern and it requires network quality of service
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(QoS) for best performance. It may also require an
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active queue management implementation to ensure
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delivery. Users are very sensitive to latency and
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jitter fluctuations and can detect them at very low
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levels.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>Video Conference or web conference</term>
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<listitem>
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<para>This also is
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extremely sensitive to network congestion, latency,
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jitter and other network flaws. Video Conferencing has
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a symmetrical traffic pattern, but unless the network
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is on an MPLS private network, it cannot use network
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quality of service (QoS) to improve performance.
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Similar to VOIP, users will be sensitive to network
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performance issues even at low levels.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>High performance computing (HPC)</term>
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<listitem>
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<para>This is a complex
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use case that requires careful consideration of the
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traffic flows and usage patterns to address the needs
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of cloud clusters. It has high East-West traffic
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patterns for distributed computing, but there can be
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substantial North-South traffic depending on the
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specific application.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<xi:include href="network_focus/section_user_requirements_network_focus.xml"/>
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<xi:include href="network_focus/section_tech_considerations_network_focus.xml"/>
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<xi:include href="network_focus/section_operational_considerations_network_focus.xml"/>
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<xi:include href="network_focus/section_architecture_network_focus.xml"/>
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<xi:include href="network_focus/section_prescriptive_examples_network_focus.xml"/>
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</chapter>
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