Repository: incubator-geode Updated Branches: refs/heads/develop ddc4819b0 -> c9e3b0540
GEODE-2101 Improve WAN topology terminology in docs The terms parallel and serial are not right, so change them: - a parallel multi-site topology is a fully connected mesh - a serial multi-site topology is a ring Project: http://git-wip-us.apache.org/repos/asf/incubator-geode/repo Commit: http://git-wip-us.apache.org/repos/asf/incubator-geode/commit/c9e3b054 Tree: http://git-wip-us.apache.org/repos/asf/incubator-geode/tree/c9e3b054 Diff: http://git-wip-us.apache.org/repos/asf/incubator-geode/diff/c9e3b054 Branch: refs/heads/develop Commit: c9e3b05405a2e82a00f9b3ac15ed259a2829a053 Parents: ddc4819 Author: Karen Miller <[email protected]> Authored: Mon Nov 14 10:07:14 2016 -0800 Committer: Karen Miller <[email protected]> Committed: Mon Nov 14 15:56:24 2016 -0800 ---------------------------------------------------------------------- .../multisite_topologies.html.md.erb | 69 ++++++++++++++++---- 1 file changed, 55 insertions(+), 14 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/incubator-geode/blob/c9e3b054/geode-docs/topologies_and_comm/multi_site_configuration/multisite_topologies.html.md.erb ---------------------------------------------------------------------- diff --git a/geode-docs/topologies_and_comm/multi_site_configuration/multisite_topologies.html.md.erb b/geode-docs/topologies_and_comm/multi_site_configuration/multisite_topologies.html.md.erb index 4b5753b..b710b8d 100644 --- a/geode-docs/topologies_and_comm/multi_site_configuration/multisite_topologies.html.md.erb +++ b/geode-docs/topologies_and_comm/multi_site_configuration/multisite_topologies.html.md.erb @@ -27,41 +27,82 @@ This section describes Geode's support for various topologies. Depending on your - When a Geode site receives a message from a gateway sender, it forwards it to the other sites it knows about, excluding those sites that it knows have already seen the message. Each message contains the initial sender's ID and the ID of each of the sites the initial sender sent to, so no site forwards to those sites. However, messages do not pick up the ID of the sites they pass through, so it is possible in certain topologies for more than one copy of a message to be sent to one site. - In some configurations, the loss of one site affects how other sites communicate with one another. -## <a id="multisite_topologies__section_7ECE1AFB1F94446FAA0A9FD504217C76" class="no-quick-link"></a>Parallel Multi-site Topology - -A parallel network topology is one where all sites know about each other. This is a robust configuration, where any one of the sites can go down without disrupting communication between the other sites. A parallel topology also guarantees that no site receives multiple copies of the same message. - -The parallel topology for three sites is shown in this figure. In this scenario, if site 1 sends an update to site 2, site 2 forwards to site 3. If site 1 sends an update to sites 2 and 3, neither forwards to the other. Likewise for any other initiating site. If any site is removed, the remaining two maintain a parallel topology. +## <a id="multisite_topologies__section_7ECE1AFB1F94446FAA0A9FD504217C76" class="no-quick-link"></a>Fully Connected Mesh Topology + +A fully connected mesh network topology is one in which all sites +know about each other. +This is a robust configuration, +as any one of the sites can go down without disrupting communication +between the other sites. +A fully connected mesh topology also guarantees that no site receives +multiple copies of the same message. + +A fully connected mesh with three sites is shown in this figure. +In this scenario, if site 1 sends an update to site 2, +site 2 forwards to site 3. +If site 1 sends an update to sites 2 and 3, +neither forwards to the other. +This is likewise true for any other initiating site. +If any site is removed, the remaining two are still fully connected. <img src="../../images/multisite-topology-parallel.png" id="multisite_topologies__image_6CB125A80DF74DCE96A94020F7003DAE" class="image" /> -## <a id="multisite_topologies__section_17EC1FD63A5241159FE2ED07F72CD5DC" class="no-quick-link"></a>Serial Multi-site Topology +## <a id="multisite_topologies__section_17EC1FD63A5241159FE2ED07F72CD5DC" class="no-quick-link"></a>Ring Topology -A serial network topology is one where each site only knows about one other site. Data is passed from one site to the next serially. This figure shows the topology for three sites. In this scenario, if site 1 sends updates to site 2, site 2 forwards to site 3. Site 3 does not send the updates back to site 1. +A ring topology is one in which each site forwards information +to one other site, +and the sites are connected in a circular manner. +This figure shows a ring with three sites. +In this topology, if site 1 sends updates to site 2, +site 2 forwards the updates to site 3. +No updates are forwarded to the original sender, +so site 3 does not send the updates back to site 1. <img src="../../images/multisite-topology-serial.png" id="multisite_topologies__image_876567BB077C4398BEFB13EEC34DA53C" class="image" /> -The serial topology guarantees that every site receives one copy of each message sent by any site. With a serial installation, every site must stay up to maintain the topology. The failure of any site breaks the serial link. If site 2 went down, for example, site 3 could send to site 1, but site 1 could not send to site 3. +A ring topology guarantees that every site receives one copy of +each message sent by any site. +In a ring, every site must stay up to maintain the connection. +The failure of any site breaks the ability for updates to reach +all sites. +If site 2 went down, for example, +site 3 could send to site 1, but site 1 could not send to site 3. ## <a id="multisite_topologies__section_AA3A864753DF4C218133C0A7460D2D19" class="no-quick-link"></a>Hybrid Multi-site Topology -A hybrid network topology contains both parallel and serial connections. There are numerous such configurations. +There are numerous hybrid network topologies. +Some of the sites are fully connected, while others form a ring. -The following figure shows a hybrid topology composed of a serial topology with an additional link directly from site 1 to site 3, creating a parallel topology between sites 1 and 3. With this topology, no site can receive the same update twice. +The following figure shows a hybrid topology that forms a ring, +with an extra connection that fully connects +sites 1 and 3. <img src="../../images/multisite-topology-hybrid-1.png" id="multisite_topologies__image_7656D6CEC2C947F8BFE67A0BB0BA5FDE" class="image" /> -With this hybrid topology, if site 2 went down, it would not affect communication between sites 1 and 3, because both could still send to the other. If site 3 went down, however, site 2 would not be able to send to site 1. +With this hybrid topology, if site 2 went down, +it would not affect communication between sites 1 and 3. +If site 3 went down, however, site 2 would not be able to send to site 1. -In the figure below, sites 2 and 3 are isolated from one another. This topology might work for an application where there is one producer (site 1) and multiple consumers that have nothing to gain from being connected to each other. This topology also guarantees that no site receives the same update twice. +A second example hybrid topology is shown in the figure below. +In this tree topology with site 1 as the root of the tree, +sites 2 and 3 do not communicate with each another. +This topology works for an application in which site 1 is a producer +and the consumers (sites 2 and 3) have nothing to gain from +being connected to each other. +This topology also guarantees that no site receives the same update twice. <img src="../../images/multisite-topology-hybrid-2.png" id="multisite_topologies__image_1904C515A3224BE09589921A15D6D59B" class="image" /> ## <a id="multisite_topologies__section_8D7912BF9D8549A491D9AE5E0DC3CC1F" class="no-quick-link"></a>Unsupported Topologies -This section lists topologies that do not work and are unsupported. +Topologies in which the same update may be delivered twice +to a particular site do not work and are unsupported. -In the topology shown in the next figure, some sites might receive multiple copies of the same message. If site 1 sends a message to sites 2 and 3, sites 2 and 3 will both forward to site 4. +The DAG topology shown in this figure is an example of an unsupported +technology. +Site 4 will receive more than one copy of the same message when +site 1 sends a message to sites 2 and 3, +and sites 2 and 3 each forward the message to site 4. <img src="../../images/multisite-topology-avoid-3.png" id="multisite_topologies__image_710EB20403C942D0B756F9D22B3359A6" class="image" />
