Error Loopback Was Detected
Contents |
SwitchingSpanning Tree ProtocolTroubleshoot and AlertsConfiguration Example and TechNotes Errdisable Port State Recovery on the Cisco IOS Platforms Download Print Available Languages Download Options PDF (143.8 KB) View with Adobe Reader on a variety of loopback error detected cisco devices ePub (82.1 KB) View in various apps on iPhone, iPad, Android, Sony Reader,
Loopback Error Detected Putting In Err-disable State
or Windows Phone Mobi (Kindle) (87.6 KB) View on Kindle device or Kindle app on multiple devices Updated:Mar 23, 2016 Document ID:69980 pm-4-err_disable link-flap error detected ContentsIntroductionPrerequisitesRequirementsComponents UsedBackground InformationPlatforms That Use ErrdisableErrdisableFunction of ErrdisableCauses of ErrdisableDetermine If Ports Are in the Errdisabled StateDetermine the Reason for the Errdisabled State (Console Messages, Syslog, and the show errdisable recovery Command)Recover a Port from %ethcntr-3-loop_back_detected: loop-back detected Errdisabled StateCorrect the Root ProblemReenable the Errdisabled PortsVerifyTroubleshootRelated Information Introduction This document defines the errdisabled state, describes how to recover from it, and provides examples of errdisable recovery. This document uses the terms errdisable and error disable interchangeably. Customers often contact Cisco Technical Support when they notice that one or more of their switch ports have become error disabled, which means that the ports have a status of errdisabled. These customers want
Pm-4-err_disable Bpduguard Error Detected
to know why the error disablement happened and how they can restore the ports to normal. Note: The port status of err-disabled displays in the output of the show interfaces interface_number status command. Prerequisites Requirements There are no specific requirements for this document. Components Used In order to create the examples in this document, you need two Cisco Catalyst 4500/6500 Series Switches (or the equivalent) in a lab environment with cleared configurations. The switches should run Cisco IOSĀ® Software and each switch should have two Fast Ethernet ports that are capable of EtherChannel and PortFast. The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command. Background Information Platforms That Use Errdisable The errdisable feature is supported on these Catalyst switches: Catalyst switches that run Cisco IOS Software: 2900XL / 3500XL 2940 / 2950 / 2960 / 2970 3550 / 3560 / 3560-E / 3750 / 3750-E 4000 / 4500 6000 / 6500 Catalyst switches that run Catalyst OS (CatOS) software: 2948G 4500 / 4000 5500 / 5000 6500 / 6000 The way in which errdisable is implemen
index The team • Delete all board cookies • All times are UTC - 8 hours Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group Advertisements by Advertisement Management
IP isWhoisCalculatorTool PointsNewsNews tip?ForumsAll ForumsHot TopicsGalleryInfoHardwareAll FAQsSite FAQDSL FAQCable TechAboutcontactabout uscommunityISP FAQAdd ISPISP Ind. ForumsJoin Search similar:Cisco SAP-1602i connected to 2960 trunk port[HELP] Transit VRF Question[Config] Performance due to VLAN, incomplete STP, or loop backs?[Config] Cisco Switches Trying to Carry a VLAN's trafficCisco 887VA-M-K9 can't http://www.dslreports.com/forum/r30125337-HELP-Figuring-out-the-reason-behind-err-disabled-loopback ping local LAN or the other way around Forums → Equipment Support → Hardware By Brand → Cisco → [HELP] Figuring out the reason behind err-disabled loopback. uniqs1554 Share « http://www.techexams.net/forums/ccnp/46455-loop_back_detected-some-help.html VLAN question • A little update on daily fun » techsup1983join:2013-03-23 techsup1983 Member 2015-Jun-20 4:47 am [HELP] Figuring out the reason behind err-disabled loopback.Hello all.We have a core switch (WS-C3650-48PD) error detected and there are ports which keep showingPort Name Status Reason Err-disabled VlanGi2/0/19 err-disabled loopbackis it a good idea to do the no keepalives command on the ports or would there be a way to get more information.What would be the best way to troubleshoot this?Please ask me for anything i've not mentioned. Thanks. · actions · 2015-Jun-20 4:47 am · Network loopback error detected GuyPremium Memberjoin:2000-08-25New York Network Guy Premium Member 2015-Jun-20 9:49 am Please draw up a quick and dirty MS Paint diagram of your topology, particularly where your 3650 connects to other switches. · actions · 2015-Jun-20 9:49 am · markysharkeyPremium Memberjoin:2012-12-20united kingd markysharkey to techsup1983 Premium Member 2015-Jun-21 11:52 am to techsup1983err-disable loopback could be because storm control is enabled on the port and it keeps seeing BPDU's and/or traffic from a loop.As well as the diagram Network Guy has asked for lets have see the output for the following:show run int gi 2/0/19 sho int gig 2/0/19 sho int trunk shp spanning-tree vlan x (where x is the native VLAN) The only time I see a port with the spanning-tree port-state listed as loopback is where every switch in a topology has had spanning tree disabled except for one. I used to demo this in a lab environment when I taught CCNA and was showing switching loops and how to deal with them. · actions · 2015-Jun-21 11:52 am · HELLFIREMVMjoin:2009-11-25 HELLFIRE to techsup1983 MVM 2015-Jun-21 1:51 pm to techsup1983My imm
to this Thread… rakem Senior Member Join Date May 2005 Location Sydney, Australia Posts 805 Certifications CCNA, CCNP, CCIE#38186(R&S), JNCIA-JUNOS, JNCIS-SEC, JNCIP-SEC, JNCIS-ENT, F50-531, F50-533 09-07-200911:23 PM #1 Loop_back_detected - Some help. Not an exam question here but im sure I can get some good advise here.. Today a college hooked up a new switch into our network. It was a 3560 being connected to a pair of 3750s in a stack, so one uplink went to Gi1/0/18 and the other went to Gi2/0/18. When the second cable (Cat6) was connected a bunch of our switches went down. The uplink ports went into err-disabled and the error in the log was: %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on GigabitEthernet0/48. %PM-4-ERR_DISABLE: loopback error detected on Gi0/48, putting Gi0/48 in err-disable state Now the expected behaviour was for spanning tree to just block the second connection to Gi2/0/18 and for no outage at all. In the end about 10 switches went down with the loopback error. So I have been researching the loopback error and found this link: http://www.cisco.com/application/pdf...e_recovery.pdf Which says: "A loopback error occurs when the keepalive packet is looped back to the port that sent the keepalive. The switch sends keepalives out all the interfaces by default. A device can loop the packets back to the source interface, which usually occurs because there is a logical loop in the network that the spanning tree has not blocked. The source interface receives the keepalive packet that it sent out, and the switch disables the interface (errdisable). This message occurs because the keepalive packet is looped back to the port that sent the keepalive. Keepalives are sent on all interfaces by default in Cisco IOS Software Release 12.1EA−based software. In Cisco IOS Software Release 12.2SE−