12-07-2023 04:46 PM
Hi, recently I had an issue where a mac address was flapping between two sites that are connected via a Port-channel trunk, see logs below. I determined/assume it went into err-disable state because of a spanning tree loop as our intermediary provider was having issues. What am trying to understand is if there is a way to recover from this error.
Under errdisable recovery I don’t see anything pertaining to STP or Layer 2 loops. I wanted to know if there’s a way to recover from this mac flapping error or layer 2 loop which am assuming is due to a Spanning tree loop.
3600-Stack-SW#sh errdisable recovery
ErrDisable Reason Timer Status
----------------- --------------
arp-inspection Disabled
bpduguard Disabled
channel-misconfig Disabled
dhcp-rate-limit Disabled
dtp-flap Disabled
evpn-mh-core-isolation Disabled
gbic-invalid Disabled
inline-power Disabled
l2ptguard Disabled
link-flap Enabled
mac-limit Disabled
link-monitor-failure Disabled
loopback Disabled
oam-remote-failure Disabled
pagp-flap Disabled
port-mode-failure Disabled
pppoe-ia-rate-limit Disabled
psecure-violation Disabled
security-violation Disabled
sfp-config-mismatch Disabled
storm-control Disabled
udld Disabled
psp Disabled
dual-active-recovery Disabled
evc-lite input mapping fa Disabled
Recovery command: "clear Disabled
mrp-miscabling Disabled
Dec 6 21:34:20 est: %SW_causa Host ecf4.xxxxx.xxxxx in vlan 501 is flapping between port Po2 and port Gi1/0/43
Dec 6 21:34:21 est: %SW_MATM-4-MACFLAP_NOTIF: Host ecf4.xxxxx.xxxxx in vlan 501 is flapping between port Po2 and port Gi2/0/44
Dec 6 21:34:21 est: %PM-4-ERR_DISABLE: channel-misconfig error detected on Po2, putting Gi1/1/1 in err-disable state
Dec 6 21:34:21 est: %PM-4-ERR_DISABLE: channel-misconfig error detected on Po2, putting Gi1/1/2 in err-disable state
Dec 6 21:34:21 est: %PM-4-ERR_DISABLE: channel-misconfig error detected on Po2, putting Gi2/1/1 in err-disable state
Dec 6 21:34:22 est: %PM-4-ERR_DISABLE: channel-misconfig error detected on Po2, putting Po2 in err-disable state
Dec 6 21:34:22 est: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/1/1, changed state to down
Dec 6 21:34:22 est: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/1/2, changed state to down
Dec 6 21:34:22 est: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet2/1/1, changed state to down
Dec 6 21:34:22 est: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel2, changed state to down
Dec 6 21:34:23 est: %LINK-3-UPDOWN: Interface Vlan500, changed state to down
Dec 6 21:34:23 est: %LINK-3-UPDOWN: Interface Vlan501, changed state to down
Solved! Go to Solution.
12-09-2023 05:50 AM - edited 12-09-2023 05:54 AM
The stp effect port-channel
EtherChannel misconfig guard is enabled
This feature make port go to errdisable
Channel-misconfig must enable if you want to recovery from this errdisable
Errdisable recovery cause channel-misconfig
But But
As @balaji.bandi mention this is not good idea at all.
Errdisable put to protect your SW.
MHM
12-07-2023 10:04 PM
There are two planes
Control and data
Control use bpdu to detect loop and discard traffic in one interface if there is loop,
Data plane forward traffic via any UP interface and it stp is FWD.
Here I think ISP use filter for bpdu or one site use bpdu filter, this make control plane can not detect loop.
And cause what you see.
MHM
12-08-2023 11:45 AM
Hi, it has been determined that our ISP actually caused a L2 loop in their network which caused a loop in our shared vlans. I was just trying to figure out is when in err-disable if this is auto recoverable event.
12-08-2023 12:05 AM
My personally suggestion, when the STP Loops or error disable configuring auto-recovery is bad idea.
Instead you can troubleshoot, see where the Loops, make sure you setup and STP priority and Root for the VLAN, so they Block alternative path.
Investigate the MAC (or device) flapping between 2 Port-channel ?
%SW_MATM-4-MACFLAP_NOTIF: Host ecf4.xxxxx.xxxxx in vlan 501 is flapping between port Po2 and port Gi2/0/44
This is indication where to investigate.
%PM-4-ERR_DISABLE: channel-misconfig error detected on Po2, putting Gi1/1/1 in err-disable state
how is your configuration on this port-channel and interface associated with that.
this most likely configuration or STP issue (you need to find out that information)
12-08-2023 11:48 AM
BB, I agree with you that auto recovery for L2 loops is probably bad, but I was wondering if there is a way to do this. From the err-disable command I don't see that as an option in Cisco IOS. I mostly asked because my used was caused by my provider looping their network for a few minutes which caused my port-channel trunks to go into err-disabled. So, I'm wondering if there is a way to auto recover from this.
12-09-2023 05:24 AM
Perosnally auto-recover is bad idea, better also contact provider and check what causing this issue.
12-09-2023 05:50 AM - edited 12-09-2023 05:54 AM
The stp effect port-channel
EtherChannel misconfig guard is enabled
This feature make port go to errdisable
Channel-misconfig must enable if you want to recovery from this errdisable
Errdisable recovery cause channel-misconfig
But But
As @balaji.bandi mention this is not good idea at all.
Errdisable put to protect your SW.
MHM
12-11-2023 03:24 PM
Hi MHM, this is what I wanted to know what err-disable recovery is related to the STP loop issue I have. Although am not going to enable recovery for channel-misconfig I wanted to know what was the related recovery command. Looking back on the log it does state the following on the logs,
%PM-4-ERR_DISABLE: channel-misconfig error detected
I just didn't know that channel-misconfig was related to BPDU loop. The channel-misconfig is sort of a vague name, but now I know what is and does.
thank you.
p
12-11-2023 10:07 PM
You are so welcome
MHM
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