{"id":6364,"date":"2026-05-04T12:10:33","date_gmt":"2026-05-04T12:10:33","guid":{"rendered":"http:\/\/docs.connexite.co.uk\/index.php\/docs\/connexite-documentation\/synapse-cli-documentation\/cli-configuring-loop-detect\/"},"modified":"2026-05-04T12:19:09","modified_gmt":"2026-05-04T12:19:09","slug":"cli-configuring-loop-detect","status":"publish","type":"docs","link":"https:\/\/docs.connexite.co.uk\/index.php\/docs\/network\/synapse-cli-documentation\/cli-configuring-loop-detect\/","title":{"rendered":"Configuring LOOP-DETECT"},"content":{"rendered":"<h2 class=\"connexite-doc-h2\">Overview of LOOP-DETECT<\/h2>\n<p>LOOP-DETECT is an Ethernet loop detection protocol, which is used to quickly detect loop faults on downlink interfaces. If a fault is found, LOOP-DETECT will notify the user to manually close or automatically close the relevant port according to the fault handling method configured by the user, so as to avoid affecting the normal data exchange. Enable control: Enable control is divided into global enable control and port enable control. When the global enable control is enabled and the loop detection is enabled on the port, the port supports the loop detection function. Loop action: When a loop fault is detected on the port, the user will be notified to manually handle the loop fault by default, and the automatic closing of the port can also be configured. When the port is automatically shut down, the port can recover from the fault by waiting for timeout, shutdown\/no shutdown port, recovery command, or restarting the device. Specify vlan: By default, the port vlan attribute is ignored; if you need to detect whether a loop fault occurs in a specific vlan domain, you can configure the specified vlan on the port, and only detect Whether there is a loop data path in this vlan domain. The device supports loop fault alarm and loop fault recovery message traps to the snmp server, which is disabled by default.<\/p>\n<h2 class=\"connexite-doc-h2\">Configuring<\/h2>\n<p>Enable LOOP-DETECT Globally<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#no loop-detect enable<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enable the LOOP-DETECT function globally. Disabled by default. Enable LOOP-DETECT On Interface<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#no loop-detect enable<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enabe the LOOP-DETECT Function Based on Ports. Disabled by default. Supports physical ports and AP ports, does not support AP members. Note\uff1a \u2726 For a port in the block state, the protocol considers that there is no possibility of a loop. Even if the port is enabled for loop detection, the actual function cannot run normally. In an environment where stp and erps are enabled, a similar situation may exist. It is recommended to make the function mutually exclusive in the configuration.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#loop-detect action (alarm | error-down)<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#no loop-detect action<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Configure port loop action. Alarm: print alarm information. Error-down: print alarm information and shut down the port at the same time. The default action is alarm.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#loop-detect vlan VID<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#no loop-detect vlan VID<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#no loop-detect vlan<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Detect whether a data path loop occurs in the specified vlan domain. VID supports single vlan mode and range mode, such as 10-12, separated by &quot;,&quot; in the middle. A port can specify up to 8 vlans. By default, if no vlan is specified, the port vlan attribute will be ignored. If the port is in the block state, the data path is considered to be blocked.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect interval SECONDS<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#no loop-detect interval<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Configure the interval for sending loop detection packets. SECONDS: range 5-300, default 5, unit second. Set Error-down Recovery Time<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#errdisable timeout (interval SECONDS | enable | disable)<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#no errdisable timeout interval<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Configure errdisable recovery time. SECONDS: range 10-1000000, unit second. Enable: enable errdisable recovery. Disable: disable errdisable recovery. The default time is 300 seconds. The time is shared by all errdisable applications, configuring this parameter will affect other applications. Error-down Recovery Recovery interface from errdisable status. If errdisable timeout is disabled, this command will not work, please use shutdown and no shutdown commands to recovery interface.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH#errdisable recovery interface IFNAME<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Recovery Interface to normal.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect trap enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#no loop-detect trap enable<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enable trap loop fault occurrence and loop fault recovery messages to the snmp server. Disabled by default. Definition of loop alarm trap node:<\/p>\n<h2 class=\"connexite-doc-h2\">Mib files<\/h2>\n<p>DK-LDET-MIB.my oid 1, 3, 6, 1, 4, 1, 57430, 1, 6, 2,1<\/p>\n<h2 class=\"connexite-doc-h2\">Ifindex<\/h2>\n<p>port index Definition of loop alarm recovery trap node: Node Data<\/p>\n<h2 class=\"connexite-doc-h2\">Mib files<\/h2>\n<p>DK-LDET-MIB.my oid 1, 3, 6, 1, 4, 1, 57430, 1, 6, 2,2<\/p>\n<h2 class=\"connexite-doc-h2\">Ifindex<\/h2>\n<p>port index<\/p>\n<h2 class=\"connexite-doc-h2\">Examples<\/h2>\n<p>Case 1: Configure port gi0\/1 to enable the loop detection function, and configure the action to err-down.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH#configure terminal<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enter configuration commands, one per line. End with CNTL\/Z.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#interface gigabitEthernet 0\/1<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)# loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)# loop-detect action error-down<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">When port gi0\/1 detects a loop, it prompts the following information and shuts down the port. LOOPDETECT-4: %Loop error detected on interface GigabitEthernet 0\/1.set interface err-down. Case 2: Configure port gi0\/1 to perform loop detection in the vlan10 domain.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH#configure terminal<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enter configuration commands, one per line. End with CNTL\/Z.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#vlan 10<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#interface gigabitEthernet 0\/1<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)#switchport mode trunk<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)# loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)# loop-detect vlan 10<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">The port gi0\/1 sends loop detection messages with tag and vid is 10. If a loop is detected in the vlan10 domain, the log information is output. if peer interface not allow vlan10, no loop detected. LOOPDETECT-4: %Loop error detected on interface GigabitEthernet 0\/1. Case 3: Configure port gi0\/1 to enable loop detection, enable trap, and configure the snmp server 192.168.64.1.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH#configure terminal<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Enter configuration commands, one per line. End with CNTL\/Z.<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#snmp-server group public v2c read all write all<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#snmp-server community public<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#snmp-server host 192.168.64.1 traps v2c community public<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#loop-detect enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)# loop-detect trap enable<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config)#interface gigabitEthernet 0\/1<\/code><\/pre>\n<pre class=\"connexite-doc-command\"><code>SWITCH(config-if)# loop-detect enable<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">When port gi0\/1 detects a loop, the snmp server receives the loop alarm trap information.<\/p>\n<h2 class=\"connexite-doc-h2\">Display Information<\/h2>\n<p>Display LOOP-DETECT Information<\/p>\n<pre class=\"connexite-doc-command\"><code>SWITCH#show loop-detect<\/code><\/pre>\n<p class=\"connexite-doc-command-desc\">Global configuration: Loop-detect State : Enabled Loop-detect Interval \uff1a5 Loop-detect trap : Enabled Interface gigabitEthernet 0\/1: Loop-detect State : Enabled Loop-detect Action : Alarm Loop-detect Action Last : Normal Loop-detect Action Last Time : &#8212; Loop-detect Action Count : 0 Loop-detect Vlans : 10, 20, 30-32 Analysis of the information\uff1a<\/p>\n<h2 class=\"connexite-doc-h2\">Global Information<\/h2>\n<p>Loop-detect State Global enable status, Enabled or Disabled Loop-detect Interval Interval for sending loop detection packets, in seconds Loop-detect trap Whether to enable the alarm message trap to the server, Enabled or Disabled<\/p>\n<h2 class=\"connexite-doc-h2\">Interface Information<\/h2>\n<p>Loop-detect State Interface enable status, Enabled or Disabled Loop-detect Action Action after loop detection, support alarm and error-down Loop-detect Action Last The last time a failure occurred: Normal: normal Alarm: output alarm Error-down: The port is down Loop-detect Action Last Time Time of last failure: No failures have occurred:&#8211; Happened, for example: 2022-01-10 22:45:23 Loop-detect Action Count<\/p>\n<h2 class=\"connexite-doc-h2\">Count of failures<\/h2>\n<p>Loop-detect Vlans Loop packet specified vlan list<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Networking \u203a Switching \u203a Edge \u203a Synapse<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":6349,"menu_order":15,"comment_status":"open","ping_status":"closed","template":"","doc_tag":[115,119,116],"class_list":["post-6364","docs","type-docs","status-publish","hentry","doc_tag-connexite","doc_tag-network","doc_tag-synapse-cli-documentation","no-post-thumbnail"],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/docs\/6364","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=6364"}],"version-history":[{"count":1,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/docs\/6364\/revisions"}],"predecessor-version":[{"id":6412,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/docs\/6364\/revisions\/6412"}],"up":[{"embeddable":true,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/docs\/6349"}],"wp:attachment":[{"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=6364"}],"wp:term":[{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/docs.connexite.co.uk\/index.php\/wp-json\/wp\/v2\/doc_tag?post=6364"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}