Loopback Error Detected
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Pm-4-err_disable Loopback Error Detected
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Loopback Error Detected Cisco
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to find this is in the output of show interfaces status. A switch port can end be error %ethcntr-3-loop_back_detected: loop-back detected disabled if the software (IOS or CatOS) detects an error pm 4 err_disable bpduguard error detected situation on the port. The port is effectively shut down until re-enabled manually or automatically if a pm-4-err_disable channel-misconfig (stp) error detected recovery timer is specified for the error condition. One such error condition results from the existence of a loopback on the port. The switch sends keepalive packets https://supportforums.cisco.com/discussion/10905251/pm-4-errdisable-loopback-error-detected-gi02 out all interfaces. If a keepalive packet is received on the same interface it was sent from, then a loop exists that has not been blocked by Spanning-Tree Protocol. If this occurs, these messages are generated (these specific messages are from a Cisco Catalyst 2940). %ETHCNTR-3-LOOP_BACK_DETECTED: Keepalive packet loop-back detected on FastEthernet0/3.
%PM-4-ERR_DISABLE: loopback https://slaptijack.com/networking/err-disabled-loopback-edition/ error detected on Fa0/3, putting Fa0/3 in err-disable state
To resolve the problem, you must investigate the network beyond the port that is complaining and discover what sort of logical loop might exist that was undetectable by STP. Often, less capable devices (inexpensive unmanaged switches or hubs) are the culprit. Related Reading: Cisco Field Manual: Catalyst Switch Configuration by David Hucaby, Stephen McQuerry Building Cisco Multilayer Switched Networks by Richard Froom, Balaji Sivasubramanian, Erum Frahim Related Posts UDLD In Radio-Based Metro Ethernet Rings Cisco Catalyst 3560 POST Output Allowing DHCP Option 82 in Cisco DHCP Relay Agents Brand New ME3400G Can't Ping! 3 Reasons You Should Be Using Rapid Spanning Tree (802.1w) Get Slaptijack updates delivered to your Inbox or RSS Reader for free! CATEGORIES Graphics Design Information Systems IT Management Networking Programming Software System Administration Uncategorized Voice / Voice over IP ARCHIVES 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 © 2016 Slaptijack All Rights Reserved · Wordpress
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 http://www.dslreports.com/forum/r30125337-HELP-Figuring-out-the-reason-behind-err-disabled-loopback a VLAN's trafficCisco 887VA-M-K9 can't ping local LAN or the other way around Forums → Equipment Support → Hardware By Brand → Cisco → [HELP] Figuring out the reason behind http://ithitman.blogspot.com/2012/04/troubleshooting-loop-back-detected-pm-4.html err-disabled loopback. uniqs1586 Share « 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 error detected all.We have a core switch (WS-C3650-48PD) 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. · loopback error detected actions · 2015-Jun-20 4:47 am · tired_runnerPremium Memberjoin:2000-08-25New York tired_runner 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
of the interfaces was err-disabled. FunMondaymornings :) andsiftingthrough the logs I came up on this error message. %PM-4-ERR_DISABLE: loopback error detected on Fa1/0/20, putting Fa1/0/20 in err-disable state %ETHCNTR-3-LOOP_BACK_DETECTED: Loop-back detected on FastEthernet1/0/20. Turns out that this was because of an interface somewhere in our network was configured incorrectly which then created a loop in our network.The STP topology in our network corrected/recovered itself within a few seconds and fa1/0/20 should have "err-disabled recovered", however "errdisable recovery cause loopback"was not configured. Basically this error message states that the keepalives which are on by default are looping back to the source interface. For example, if a keepalive was sent on fa1/0/20 and if that keepalive packet loops around the network and shows up at the source interface then that must mean that there is a loop in our network and the interface which sent out the keepalive will be err-disable. Notice that the keepalive are set to 10sec by default on all interfaces. Workarounds: Fix the underlying misconfigured interface downstream and/or upstream. Disable keepalives on interfaces. Many more articles to come so stay tuned. "Join this site" on the right / click +1 below -------> Posted by Arwin Reprakash Email ThisBlogThis!Share to TwitterShare to FacebookShare to Pinterest Labels: STP, Troubleshooting Newer Post Older Post Home Subscribe to: Post Comments (Atom) Search This Blog Loading... Popular Posts What are TCP Spurious Retransmissions? First time I saw on "TCP Spurious Retransmissions" on Wireshark, I had to look up the definition of Spurious on Google as I'v... Understanding TCP Window Size / Window Scaling The easiest way to understand TCP Window size is to observe two people having a conversation. Every so often, the talker will wait for the l... CCIE v5 INE Home Lab - Part 1 - Configuring VMware ESXi "Every day you wake up you have two options, you can either look at the clock at 3:30am, tap the snooze button, go back to sleep, and d... Blog Archive ► 2016 (1) ► Apr 10 - Apr 17 (1) ► 2015 (22) ► Dec 20 - Dec 27 (1) ► Dec 13 - Dec 20 (1) ► Dec 6 - Dec 13 (2) ► Nov 29 - Dec 6 (3) ► Nov 22 - Nov 29 (1) ► Oct 25 - Nov 1 (1) ► May 17 - May 24 (2) ► Apr 26 - May 3 (1) ► Apr 12 - Apr 19 (1) ► Apr 5 - Apr 12 (3) ► Mar 22 - Mar 29 (1) ► Mar 15 - Mar 22 (1) ► Mar 8 - Mar 15 (1) ► Feb 8 - Feb 15 (1) ► Feb 1 - Feb 8 (1) ► Jan 4 - Jan 11 (1) ► 2014 (18) ► Dec 28 - Jan 4 (1) ►