{"id":36394,"date":"2019-10-31T22:11:24","date_gmt":"2019-10-31T19:11:24","guid":{"rendered":"https:\/\/prohoster.info\/blog\/podrobnosti-realizatsii-protokolov-rstp-i-proprietarnogo-extended-ring-redundancy\/"},"modified":"2019-10-31T22:11:24","modified_gmt":"2019-10-31T19:11:24","slug":"podrobnosti-realizatsii-protokolov-rstp-i-proprietarnogo-extended-ring-redundancy","status":"publish","type":"post","link":"https:\/\/prohoster.info\/en\/blog\/administrirovanie\/podrobnosti-realizatsii-protokolov-rstp-i-proprietarnogo-extended-ring-redundancy","title":{"rendered":"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"<p>There is a wealth of material available on the RSTP protocol. In this article, I will compare the RSTP protocol with a proprietary protocol from <noindex><a rel=\"nofollow\" href=\"http:\/\/www.phoenixcontactpro.ru\">Phoenix Contact <\/a><\/noindex>\u2013 Extended Ring Redundancy.<noindex><a rel=\"nofollow\" name=\"habracut\"><\/a><\/noindex><\/p>\n<p><b>Details of RSTP implementation<\/b><\/p>\n<p><b>General information<\/b><\/p>\n<p><i>Convergence time<\/i> \u2013 1-10 s<br \/>\n<i>Possible topologies<\/i> \u2013 any<\/p>\n<p>It is commonly believed that RSTP allows switches to be grouped only in a ring:<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/6cc708e397d6fbfd3d3ff0bd67dab9dc.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nHowever, RSTP allows switches to be connected in any configuration. For instance, RSTP can handle the following topology.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/f204b8915afaae5183a0be55c660385d.jpg\" style=\"display:block;margin: 0 auto;\" \/><\/p>\n<p><b>Operating principle<\/b><\/p>\n<p>RSTP reduces any topology to a tree structure. One of the switches becomes the center of the topology \u2013 the root switch. The root switch processes the largest amount of data.<\/p>\n<p>The principle of RSTP operation is as follows:<\/p>\n<ol>\n<li>power is supplied to the switches;<\/li>\n<li>a root switch is selected;<\/li>\n<li>the remaining switches determine the fastest path to the root switch;<\/li>\n<li>the remaining links are blocked and become backups.<\/li>\n<\/ol>\n<p>\n<i>Selection of the root switch<\/i><\/p>\n<p>Switches using RSTP exchange BPDU packets. BPDU is a service packet that contains information for RSTP. There are two types of BPDU:<\/p>\n<ul>\n<li>Configuration BPDU.<\/li>\n<li>Topology Change Notification.<\/li>\n<\/ul>\n<p>\nConfiguration BPDU is used for topology creation. It is sent only by the root switch. Configuration BPDU contains:<\/p>\n<ul>\n<li>sender identifier (Bridge ID);<\/li>\n<li>root switch identifier (Root Bridge ID);<\/li>\n<li>port identifier from which this packet is sent (Port ID);<\/li>\n<li>cost of the path to the root switch (Root Path Cost).<\/li>\n<\/ul>\n<p>\nTopology Change Notification can be sent by any switch. They are sent in the event of a topology change.<\/p>\n<p>Upon startup, all switches consider themselves as root switches. They begin transmitting BPDU packets. As soon as a switch receives a BPDU with a lower Bridge ID than its own, it ceases to consider itself as root.<\/p>\n<p>The Bridge ID consists of two values \u2013 MAC address and Bridge Priority. We cannot change the MAC address. The default Bridge Priority is 32768. If the Bridge Priority is not changed, the root switch will be the one with the lowest MAC address. The switch with the lowest MAC address is the oldest and possibly not the most performant. It is recommended to manually define the root switch of the topology. To do this, a small Bridge Priority (for example, 0) should be configured on the root switch. A backup root switch can also be defined by assigning it a slightly higher Bridge Priority (for example, 4096).<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/f5142141d67a8d8704b8caa5c4f20109.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Choosing a path to the root switch<\/i><\/p>\n<p>The root switch broadcasts BPDU packets to all active ports. BPDU has a Path Cost field. Path Cost indicates the cost of the path. The higher the cost of the path, the longer it takes for the packet to travel through it. When a BPDU passes through a port, the cost is added to the Path Cost. The additional number is called the Port Cost.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/99a7fa4cd3eec220285a4c83545d8bb4.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nA specific value is added to the Path Cost as the BPDU passes through any port. This added value is called the Port Cost and can be defined either manually or automatically.<\/p>\n<p>When a non-root switch has multiple alternative paths to the root, it selects the fastest one. It compares the Path Costs of these paths. The port from which the BPDU with the lowest Path Cost arrived becomes the root (Root Port).<\/p>\n<p> <img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/49817c79ddadb0019986b67568123739.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/c4bd719750839a627771aeee41b45ae5.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/861e37223cc924163d9e71e9ff06bdb2.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nThe automatically assigned port costs can be found in the table:<\/p>\n<p>Port data transmission rate<br \/>\nPort cost<\/p>\n<p>10 Mb\/s<br \/>\n2 000 000<\/p>\n<p>100 Mb\/s<br \/>\n200 000<\/p>\n<p>1 Gb\/s<br \/>\n20 000<\/p>\n<p>10 Gb\/s<br \/>\n2 000<\/p>\n<p>\n<i>Port roles and statuses<\/i><\/p>\n<p>Switch ports have several statuses and roles.<\/p>\n<p><i>Port statuses (for STP):<\/i><\/p>\n<ul>\n<li>Disabled \u2013 inactive.<\/li>\n<li>Blocking \u2013 listens to BPDU but does not forward. Does not transmit data.<\/li>\n<li>Listening \u2013 listens and forwards BPDU. Does not transmit data.<\/li>\n<li>Learning \u2013 listens and forwards BPDU. Prepares to transmit data \u2014 fills the MAC address table.<\/li>\n<li>Forwarding \u2013 transmits data, listens and forwards BPDU.<\/li>\n<\/ul>\n<p>\nThe convergence time for STP is 30-50 seconds. After the switch is turned on, all ports go through all statuses. Each port stays in a status for several seconds. Due to this principle of operation, STP has such a long convergence time. RSTP has fewer port statuses.<\/p>\n<p>Port statuses (for RSTP):<\/p>\n<ul>\n<li>Discarding \u2013 inactive.<\/li>\n<li>Discarding \u2013 listens to BPDU but does not forward. Data is not forwarded.<\/li>\n<li>Discarding \u2013 listens to and forwards BPDU. Data is not forwarded.<\/li>\n<li>Learning \u2013 listens and forwards BPDU. Prepares to transmit data \u2014 fills the MAC address table.<\/li>\n<li>Forwarding \u2013 transmits data, listens and forwards BPDU.<\/li>\n<li>In RSTP, the statuses Disabled, Blocking, and Listening are combined into one \u2013 Discarding.<\/li>\n<\/ul>\n<p>\nPort Roles:<\/p>\n<ul>\n<li>Root port \u2013 the port through which data is transmitted. It serves as the fastest path to the root switch.<\/li>\n<li>Designated port \u2013 the port through which data is transmitted. It is defined for each LAN segment.<\/li>\n<li>Alternate port \u2013 the port through which data is not transmitted. It serves as an alternative path to the root switch.<\/li>\n<li>Backup port \u2013 the port through which data is not transmitted. It serves as a backup path for the segment where one port supporting RSTP is already connected. The backup port is used if two switch links are connected to the same segment (i.e., a hub).<\/li>\n<li>Disabled port \u2013 RSTP is disabled on this port.<\/li>\n<\/ul>\n<p>\nThe selection of the Root Port is described above. How is the Designated port selected?<\/p>\n<p>First, let\u2019s define what a LAN segment is. A LAN segment is a collision <a class=\"wpil_keyword_link\" href=\"https:\/\/prohoster.info\/en\/domain\/\"   title=\"domain\" data-wpil-keyword-link=\"linked\"  data-wpil-monitor-id=\"4076\">domain<\/a>. For a switch or router, each port forms a separate collision domain. A LAN segment is a channel between switches or routers. In the case of a hub, all ports of the hub are in the same collision domain.<\/p>\n<p>Only one Designated Port is assigned to each segment.<\/p>\n<p>In the case of segments that already have Root Ports, it is clear. The second port of the segment becomes the Designated Port.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/1699b684ba6d856905782ff8de3b90ac.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nHowever, there remain backup channels where there will be one Designated Port and one Alternate Port. How will they be selected? The Designated Port will be the port with the lowest Path Cost to the root switch. If the Path Costs are equal, then the Designated Port will be the port located on the switch with the lowest Bridge ID. If both Bridge IDs are equal, then the Designated Port becomes the port with the lowest number. The second port will be the Alternate.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/da1304c9922f1e2d738d66e543b3818e.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/341ea14a428914bd0d86c7c79ad6dbcb.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nOne last point remains: when is a port assigned the role of Backup? As mentioned above, the Backup port is used only when two switch channels are connected to the same segment, that is, to a hub. In this case, the Designated Port is selected according to the same criteria:<\/p>\n<ul>\n<li>Lowest Path Cost to the root switch.<\/li>\n<li>Lowest Bridge ID.<\/li>\n<li>Lowest Port ID.<\/li>\n<\/ul>\n<p>\n<b>Maximum number of devices in the network.<\/b><\/p>\n<p>The IEEE 802.1D standard does not impose strict requirements on the number of devices in a LAN with RSTP. However, it recommends using no more than 7 switches in one branch (no more than 7 hops), i.e., no more than 15 in a ring. Exceeding this value begins to increase network convergence time.<\/p>\n<p><b>Implementation details of ERR.<\/b><\/p>\n<p><b>General information<\/b><\/p>\n<p><i>Convergence time<\/i><\/p>\n<p>The convergence time for ERR is 15 ms. With the maximum number of switches in the ring and the presence of ring coupling, it is 18 ms.<\/p>\n<p><i>Possible topologies<\/i><\/p>\n<p>ERR does not allow devices to be freely combined like RSTP. ERR has clear topologies that can be used:<\/p>\n<ul>\n<li>Ring<\/li>\n<li>Dual Ring<\/li>\n<li>Coupling of up to three rings<\/li>\n<\/ul>\n<p>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/a54a8f3717948eb9066e6940f064962d.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Ring<\/i><\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/f905a0d6a789fc16fb0fbaea5f47e861.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nWhen all switches in ERR are combined into one ring, each switch must be configured with the ports that will participate in building the ring.<\/p>\n<p><i>Double ring<\/i><br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/c578e1191b924f81d6cae1392f6b5fd5.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nSwitches can be combined into a double ring, significantly increasing the reliability of the ring.<\/p>\n<p>Limitations of the double ring:<\/p>\n<ul>\n<li>A double ring cannot be used to couple switches with other rings. For this, Ring Coupling must be used.<\/li>\n<li>A double ring cannot be used for ring coupling.<\/li>\n<\/ul>\n<p>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/53ac9708e0cb2bf015022a0b419fb0eb.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/0cb44b8e9256304cb9d75a98e9a43ec1.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<i>Ring Coupling<\/i><\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/3a140cd59223bd91d3871dd7d2b1710a.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nWhen coupling, there can be no more than 200 devices in the network.<\/p>\n<p>Ring coupling implies combining the remaining rings into another ring.<\/p>\n<p>If a ring connects to a coupling ring through one switch, it is called <b>coupling rings through one switch.<\/b>. If two switches from the local ring connect to the coupling ring, it will be <b>coupling through two switches.<\/b>.<\/p>\n<p>When coupling through one switch, both ports of the device are used. The convergence time in this case will be approximately 15-17 ms. In such coupling, the coupling switch becomes a point of failure, as losing this switch results in losing the entire ring. Coupling through two switches helps to avoid this.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/0b92b7b888a08794e21d3d2e061fd23e.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/46121d428a21674a437544be007ed00a.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nIt is possible to couple duplicated rings.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/3864138dcc5e82b9e12753eef2292bbd.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\n<i>Path Control<\/i><br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/177a49f38e69c754de7af0b36d0c62e0.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nThe Path Control function allows configuring the ports through which data will be transmitted in normal operation. If a channel fails and the network switches to a backup topology, after the channel is restored, the network will switch back to the specified topology.<\/p>\n<p>This feature allows savings on backup cables. Moreover, the used topology will always be known for troubleshooting.<\/p>\n<p>The primary topology switches to the backup in 15 ms. The reverse switch during network recovery will take about 30 ms.<\/p>\n<p>Limitations:<\/p>\n<ul>\n<li>Cannot be used with Dual Ring.<\/li>\n<li>The feature must be enabled on all switches in the network.<\/li>\n<li>One of the switches is configured as the master Path Control.<\/li>\n<li>The automatic switch to the primary topology after recovery occurs after 1 second by default (this parameter can be changed via SNMP in the range from 0 to 99 seconds).<\/li>\n<\/ul>\n<p>\n<b>Operating principle<\/b><\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/15b569669736d2cf9c6b0c0598b843fe.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nOperation principle of ERR<\/p>\n<p>For example, consider six switches \u2013 1-6. The switches are connected in a ring. Each switch uses two ports to connect to the ring and keeps their statuses. The switches forward the statuses of the ports to each other. These data are used by the devices to establish the original state of the ports.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/930fe8518756e8cf9acab76087c81198.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\nThe ports have only two roles \u2013 <b>Blocked<\/b> and <b>Forwarding<\/b>.<\/p>\n<p>The switch with the highest MAC address blocks its port. All other ports in the ring forward data.<\/p>\n<p>If the Blocked port stops working, the next port with the highest MAC address becomes Blocked.<\/p>\n<p>After loading, the switches start sending Ring Protocol Data Units (R-PDU). R-PDU is transmitted via multicast. R-PDU is a service message, similar to BPDU in RSTP. R-PDU contains the status of the switch's ports and its MAC address. <\/p>\n<p><i>Algorithm for actions during link failure<\/i><br \/>\nWhen a link fails, the switches send R-PDU to notify about the change in port status.<\/p>\n<p><i>Algorithm for actions during link recovery<\/i><br \/>\nWhen the failed link is reactivated, the switches send R-PDU to notify about the change in port status.<\/p>\n<p>The switch with the highest MAC address becomes the new root switch.<\/p>\n<p>The failed link becomes backup.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/863a98f53a8792935ef492b2a798b8ef.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/e0972cdee89606adec01a2924f907a8e.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/3e873198ff0a68bd09627408ff465722.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/dff04828d8778263c4808ccd7594eefb.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/dfdb2a89ce223f0fa0eda950d411aaba.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nAfter recovery, one of the ports on the link remains blocked, while the other is set to forwarding state. The port with the highest speed becomes the blocked port. If the speeds are equal, the port of the switch with the highest MAC address will be blocked. This principle allows to block the port that will transition from a blocked state to a forwarding state at the maximum speed.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/911468a4eb3902af9ffc3bdc51958604.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\n<b>Maximum number of devices in the network.<\/b><\/p>\n<p>The maximum number of switches in an ERR ring is 200. <\/p>\n<p><b>Interaction between ERR and RSTP<\/b><\/p>\n<p>RSTP can be used in conjunction with ERR. However, the RSTP ring and the ERR ring should only intersect through one switch.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/ae522f0abf9c406542210fb8bce900fa.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\n<b>Summary<\/b><\/p>\n<p>ERR is well-suited for organizing standard topologies, such as a ring or a duplicated ring.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/5924f05c3395ac6e220b8d70a6dba79d.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\n<img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/a2172fb28d3b37d01aea94d6673cc921.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nSuch topologies are often used for redundancy in industrial facilities.<\/p>\n<p>Moreover, with ERR, a second topology can be implemented in a less reliable but more budget-friendly way using a duplicated ring.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/08441dd845733c46b7d0e00d7e6de37b.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n<br \/>\nHowever, ERR may not always be applicable. There are sufficiently exotic schemes. One of our clients tested the following topology.<\/p>\n<p><img decoding=\"async\" alt=\"Details of RSTP protocol implementation and proprietary Extended Ring Redundancy\" src=\"\/wp-content\/uploads\/2019\/07\/e55fa8e688e2a66a44f36f854a2e4ad6.jpg\" style=\"display:block;margin: 0 auto;\" \/><br \/>\n <br \/>\nIn this case, applying ERR is not feasible. For this scheme, we used RSTP. The client had a strict requirement for convergence time\u2014less than 3 seconds. To achieve this timing, it was essential to clearly define the root switches (primary and backup) and the port costs manually.<\/p>\n<p>As a result, ERR shows a significant advantage in convergence time but does not provide the flexibility that RSTP does.<br \/>\n<br \/>Source: <a content=\"nofollow\" rel=\"nofollow\" href=\"https:\/\/habr.com\/ru\/company\/phoenix_contact\/blog\/460633\/\">habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"<p>\u0412 \u0441\u0435\u0442\u0438 \u043c\u043e\u0436\u043d\u043e \u043d\u0430\u0439\u0442\u0438 \u043c\u043d\u043e\u0433\u043e \u043c\u0430\u0442\u0435\u0440\u0438\u0430\u043b\u043e\u0432 \u043f\u0440\u043e \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b RSTP. \u0412 \u0440\u0430\u043c\u043a\u0430\u0445 \u0434\u0430\u043d\u043d\u043e\u0439 \u0441\u0442\u0430\u0442\u044c\u0438 \u044f \u043f\u0440\u0435\u0434\u043b\u0430\u0433\u0430\u044e \u0441\u0440\u0430\u0432\u043d\u0438\u0442\u044c \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b RSTP \u0441 \u043f\u0440\u043e\u043f\u0440\u0438\u0435\u0442\u0430\u0440\u043d\u044b\u043c \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u043e\u043c \u043e\u0442 Phoenix Contact \u2013 Extended Ring Redundancy. \u041f\u043e\u0434\u0440\u043e\u0431\u043d\u043e\u0441\u0442\u0438 \u0440\u0435\u0430\u043b\u0438\u0437\u0430\u0446\u0438\u0438 RSTP \u041e\u0431\u0449\u0438\u0435 \u0441\u0432\u0435\u0434\u0435\u043d\u0438\u044f \u0412\u0440\u0435\u043c\u044f \u0441\u0445\u043e\u0434\u0438\u043c\u043e\u0441\u0442\u0438 \u2013 1-10 c \u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u0442\u043e\u043f\u043e\u043b\u043e\u0433\u0438\u0438 \u2013 \u043b\u044e\u0431\u0430\u044f \u0420\u0430\u0441\u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u043e \u043c\u043d\u0435\u043d\u0438\u0435, \u0447\u0442\u043e RSTP \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043e\u0431\u044a\u0435\u0434\u0438\u043d\u0438\u0442\u044c \u043a\u043e\u043c\u043c\u0443\u0442\u0430\u0442\u043e\u0440\u044b \u0442\u043e\u043b\u044c\u043a\u043e \u0432 \u043a\u043e\u043b\u044c\u0446\u043e: \u041d\u043e RSTP \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 [&hellip;]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":27236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-36394","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 5.0.1.1 - aioseo.com -->\n\t<meta name=\"description\" content=\"\u0412 \u0441\u0435\u0442\u0438 \u043c\u043e\u0436\u043d\u043e \u043d\u0430\u0439\u0442\u0438 \u043c\u043d\u043e\u0433\u043e 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