openstack-manuals/doc/arch-design/ch_network_focus.xml

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    <title>Network focused</title>

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

    <xi:include href="network_focus/section_user_requirements_network_focus.xml"/>
    <xi:include href="network_focus/section_tech_considerations_network_focus.xml"/>
    <xi:include href="network_focus/section_operational_considerations_network_focus.xml"/>
    <xi:include href="network_focus/section_architecture_network_focus.xml"/>
    <xi:include href="network_focus/section_prescriptive_examples_network_focus.xml"/>

</chapter>